EPA-6QO/2-76-300
December 1976
Environmental Protection Technology Series
PROTOTYPE SYSTEM FOR PLUGGING LEAKS IN
RUPTURED CONTAINERS
Industrial Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to repair or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-76-300
December 1976
PROTOTYPE SYSTEM FOR PLUGGING LEAKS
IN RUPTURED CONTAINERS
by
J. J. Vrolyk
R. C. Mitchell
R. W. Melvold
Rocketdyne Division
Rockwell International Corporation
Canoga Park, California 91304
Contract 68-03-0234
Project Officer
Ira Wilder
Oil and Hazardous Materials Spills Branch
Industrial Environmental Research Laboratory-Cincinnati
Edison, New Jersey 08817
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Industrial
Environmental Research Laboratory-Cincinnati, U,S,
Environmental Protection Agency, and approved for
publication. Approval does not signify that the
contents necessarily reflect the views and poli^
cies of the U. S. Environmental Protection Agency,
nor does mention of trade names or commercial
products constitute endorsement or recommendation
for use,
ii
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FOREWORD
When energy and material resources are extracted, processed, converted, and
used, the related pollutional impacts on our environment and even on our
health often require that new and increasingly more efficient pollution con-
trol methods be used. The Industrial Environmental Research Laboratory -
Cincinnati (lERL-Ci) assists in developing and demonstrating new and improved
methodologies that will meet these needs both efficiently and economically.
This report describes the development of a prototype system to temporarily
stop the flow of hazardous materials spilling on land or under water from
ruptured or damaged containers. The system uses foamed-in-place polyurethane
foam plugs surrounded by a flexible protective membrane for sealing leaks.
The plugging device is portable, integrated and field-operable by one man.
By stopping or restricting the release of hazardous materials from ruptured
containers, the environmental effects of such spills are minimized and the
clean-up operations are greatly facilitated. This report should be of value
to Federal, state and local government personnel as well as to individuals
from the chemical process and transportation industries who are involved in
responding to accidental releases of hazardous substances. Information on
this subject beyond that supplied in the report may be obtained from the Oil
and Hazardous Materials Spills Branch (IERL), Edison, New Jersey 08817.
David G. Stephan
Director
Industrial Environmental Research Laboratory
Cincinnati
ill
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CONTENTS•
Page
FOREWORD iii
List of Figures vi
List of Tables vii
Acknowledgments viii
I Introduction 1
II Summary 3
III Conclusions 5
IV Recommendations 7
V Development Work 8
Background Work 8
Preliminary Development Tests 9
Applicator Development 12
Foam Supply System Development 26
Chemical Compatibility 30
Test Facility 33
VI Prototype System 35
System Description 35
Pneumatically Operated Delivery System 37
Mechanically Operated Delivery System 41
Applicator 43
Methods of Use 47
Observations from Prototype Testing 54
Operating Characteristics 56
Implementation Plan 78
VII References 82
VIII Publications and Patents 83
IX Appendices 84
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LIST OF FIGURES
Number Page
1 Foam-Filled Balloon Concept 11
2 Expanding Rubber Cone Plug 14
3 Expanding Rubber Cone Applicator (Before Use) ... 15
4 Expanding Rubber Cone and Dome Applicator (After Use) . 15
5 Photograph of Plug With Expanding Rubber Cone Applicator 17
6 Photograph of Plug With Expanding Rubber Cone Applicator 18
7 Toggle and Dome Applicator 20
8 Foam Composite Applicator 23
9 Foam Composite Applicator After Use to Plug Leak . . 23
10 Alternative Foam Composite Applicator 24
11 Test Facility in Use 34
12 Basic Concept of Prototype Leak-Plugging System ... 36
13 Schematic Diagram of Pneumatically Operated Prototype
Foam Delivery System 38
14 Pneumatically Operated Prototype Foam Delivery System . 39
15 Mechanically Operated Prototype Foam Delivery System . 42
16 Prototype Applicator 44
17 Prototype Applicator After Plugging 45
18 Sectioned Prototype Applicator After Plugging ... 46
19 Prototype Applicator for Cracks 48
20 Back-Mounted Leak-Plugging System Ready for Use ... 49
21 Gushing Liquid Leak in Test Facility 51
22 Applicator Just Inserted Into Leak 51
23 Leak Slows as Applicator Expands 52
24 Leak Stopped by Full Applicator Expansion 52
25 Close-Up of Complete Plug 53
26 Completed Plug After Removal From Tank 53
27 Maximum Fluid Head in Various Containers 74
28 Envelope of Practical Fluid Head and Leak Sizes
for One-Man Operation 75
29 Envelope of Practical Applications for Sealing
Leaks in Nonsubmerged Containers 77
VI
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LIST OF TABLES
Number
1 Urethane Foam Systems Evaluated , 28
2 Static Compatibility of Leak-Plugging Materials
With Various Chemicals * 31
3 Effects of Hazardous Chemical on Physical Properties
on Leak-Plugging Materials 32
4 Probable Leak-Plugging Success With Hazardous Chemicals
Listed in 40 CFR Part 116 (&ef. 4) 60
Vll
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ACKNOWLEDGEMENTS
The support of the project by the U.- S. Environmental Protection Agency
and the interest and involvement exhibited by the Proj ect Officer, Ira
Wilder, are acknowledged with sincere thanks.
This project was conducted in the Advanced Programs Department at Rocket-
dyne with Dr. B. L. Tuffly, as Program Manager> responsible for overall
administration, and Dr. R. C. Mitchell, as Project Engineer, responsible
for the technical content and conduct of the program. Messrs. J. J.
Vrolyk and R. W. Melvold performed most of the technical work on the pro-
ject. Other members of the project team were R. Doubleday, C. L. Hamer-
mesh, W. Unterberg, and E. Witucki.
vni
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SECTION I
INTRODUCTION
Tremendous quantities of chemicals are continually produced in the United
States and then shipped to various locations for use. Many of these
chemicals create environmental and public health hazards when introduced
into natural waters. The likelihood of accidental release to watercourses
is obviously increased by the many sequences involved in the production,
transfer, shipping, unloading, and ultimate utilization of the chemicals.
While it is not at all surprising that spills do occur, there must be
continued vigilance to reduce their number and severity.
Hazardous materials spills take place in a variety of ways. Dramatic
spills occur when containers are violently ruptured (sometimes accompan-
ied by fire or explosion), and large quantities of a hazardous material
are spilled almost instantaneously. A less catastrophic spill results
when the container maintains its integrity, but suffers enough damage to
allow leakage of the hazardous material at a moderate rate. The leaking
Chemical can enter the watercourse either directly (for example, as the
result of a barge accident or a land-based container falling into the
water) or by flowing or being washed into a drainage channel or percola-
ting into the ground water supply.
Countermeasures to neutralize or treat hazardous chemicals that have
already entered the waterway may require hours or days to be initiated
and may involve the very difficult problem of handling large volumes of
water. There is a vital need for systems that can stop leaks and thereby
prevent further dispersion of spilling hazardous chemicals. Reference 1
presents an excellent overview of the problem of controlling hazardous
material spills*
The feasibility of the concept of using foamed plastic to plug leaking
chemical containers was demonstrated during a previous project (Contract
No. 68-01-0106) for the U. S. Environmental Protection Agency (Ref. 2, 3).
The objective of the current program was to develop the concept into a
practical prototype system for plugging leaks.
The leak-plugging system consists of two major components: a foam supply
device (which provides for storage of foam constituents, plus mixing,
transfer, and control of the foam) and an applicator (which places the
foam in the opening of the ruptured container in such a way as to plug
the leak, while minimizing interferences from the gushing chemical stream,
chemical action of the spilling material, and the physical characteristics
of the rupture). Development work was done on both components. Various
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aspects of operator safety and ease of use were considered. The product
of this research is an integrated, one-man, fieId-operable device that
can be used by a relatively unskilled operator wearing protective
clothing.
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SECTION II
SUMMARY
A program was performed successfully to develop and test a prototype
system for stopping the flow of hazardous materials spilling on land or
underwater from ruptured or damaged containers. The prototype system is
portable, integrated, and field-operable by one man. It seals leaks,
using foamed-in-place polyurethane rigid foam plugs covered with flexible
protective membrane.
The leak-plugging system consists of two major components: a foam supply
device (which provides for storage of foam constituents, plus mixing,
transfer, and control of the foam) and an applicator (which places the
foam in the opening of the ruptured container in an effective way to plug
the leak. The applicator has a handle with an actuating device on one
end and an applicator tip on the other end.
The tip is thrust into the hole to be plugged and the delivery system is
activated by the operator. This causes two urethane foam components to
be released from their pressurized containers, automatically mixed to-
gether as they flow, and forced into the applicator tip while it is being
held in the hole. Expansion of the foam causes the applicator tip to
expand both inside and outside the tank wall simultaneously, filling the
hole and stopping the leak. About a minute after the start of this ex-
pansion, the foam has become hard enough to permit removal of the handle
and the delivery tube; the plug is then self-supporting.
The delivery system then can be disconnected, recharged with foam compon-
ents, and attached to a new applicator tip (in the field), making the
system ready for a repeat plugging operation, if required. This repeated
use can continue over many cycles.
Particular attention was given during the prototype development work to
considerations of safety, ease of use, lightness of weight, rapid-response
capability, and other features that are important in a practical opera-
tional system. A broad range of goals for system operating character-
istics were listed at the beginning of this effort to serve as guidelines
for prototype system development. Each of these goals was achieved, to
at least a sufficient extent, to permit satisfactory use of the prototype
leak-plugging system.
The prototypes are easily portable and practical for one-man field opera-
tion with no requirement for external power, motors, or batteries. The
prototypes cause no secondary pollution problems and permit salvage of
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hazardous chemical remaining in the tank. The systems normally provide
sturdy, long-term plugging with complete or nearly complete blockage of
the leaking chemical. They provide rapid response, and would have rea-
sonable cost in production quantities.
The leak-plugging performance is unaffected by dry, wet, or dirty tank
surfaces. The system has considerable flexibility in hole size, shape,
and location. Successful plugging tests have been made with holes from
2.5 to 10 cm (1 to 4 inches) across and cracks as narrow as 1.3 cm (1/2
inch). It is expected that the present leak-plugging concept can be used
over even wider ranges of leak sizes, e.g., holes from about 1 to 30 cm
(1/2 to 12 inches) across, and cracks as thin as 0.3 cm (1/8 inch). The
prototype system can be used to plug leaks against liquid heads as high
as those normally encountered in tank cars. The system has wide tempera-
ture tolerance: about 10 to 38 C (50 to 100 F) for the foam and hardware
storage, and operation down to at least 0 C (32 F) provided the system is
not exposed to the colder temperatures for more than a brief period before
use.
The prototypes are sufficiently safe and easy to use for operation by
relatively untrained personnel wearing protective clothing. There are
only a small number of chemicals expected to be designated as "hazardous
substances" which are not feasible for leak-plugging with the system.
Limitations on applicability are primarily the result of very high vapor
pressure, excessive risk of exposure by operator, or severe chemical
reactivity.
The prototype leak-plugging system from this project has been developed
to the point that it is now realistic to project practical field use of
such a system. A preliminary implementation plan is outlined.
This report (R-9659) was submitted by the Rocketdyne Division of Rockwell
International in fulfillment of Contract 68-03-0234, under the sponsorship
of the U. S. Environmental Protection Agency.
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SECTION III
CONCLUSIONS
1. There is a vital need for systems that can prevent dispersion of a
hazardous chemical. It is far better and easier to prevent a haz-
ardous chemical from entering a waterway than it is to attempt to
remove it after entry.
2. Two successful prototype leak-plugging systems have been developed
and tested. Both systems can plug leaks of hazardous materials spil-
ling on land or under water from ruptured or damaged containers.
3. The prototypes are easily portable and practical for one-man field
operation with no requirement for external power, motors, or bat-
teries.
4. The prototypes cause no secondary pollution problems and permit sal-
vage of hazardous chemical remaining in the tank.
5. The systems normally provide sturdy, long-term plugging with complete
or nearly complete plugging.
6. The systems provide rapid response (less than 1 minute for the actual
plugging, 2 to 3 minutes including unpacking and preparation).
7. The systems are sufficiently safe and easy to use for operation by
relatively untrained personnel wearing protective clothing.
8. The system has reasonable cost (about $900 in direct cost to dupli-
cate prototypes, less to make production models).
9. There are only a small number of hazardous chemicals which are not
feasible for leak-plugging with the system. Limitations on appli-
cability are primarily the result of very high vapor pressure,
excessive risk of exposure by operator, or severe chemical reactivity.
10. The leak-plugging performance is unaffected by dry, wet, or dirty
tank surfaces.
11. The system has considerable flexibility in hole size, shape, and loca-
tion. Successful plugging tests have been made with holes from 2.5 to
10 cm (1 to 4 inches) across and cracks as narrow as 1.3 cm (1/2 inch).
It is expected that the present leak-plugging concept can be used over
wider ranges of leak sizes, e.g., holes from about 1 to 30 cm (1/2 to
12 inches) across, and cracks as thin as 0.3 cm (1/8 inch).
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12. The prototype system can be used to plug leaks against liquid heads
as high as those normally encountered in tank cars,
13. The system has wide temperature tolerance: about 10 to 38 C (50 to
100 F) for the foam and hardware storage, and operation down to at
least 0 C (32 F), provided the system is not exposed to the colder
temperatures for more than a brief period before use.
14. The prototype leak-plugging system from this project has been develop-
ed to the point that it is now realistic to project practical field
use of such a system.
15. Wide-scale field use of such a system (or any other system which
mitigates the potential effects of hazardous materials spills) will
occur only if there is a clear requirement for purchase and deploy-
ment of such equipment. Legislation or regulations probably will be
required to motivate implementation.
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SECTION IV
RECOMMENDATIONS
1, It is recommended that additional work be performed to prepare the
way for operational Use of the leak-plugging system, through develop-
ing the basis for two essential subsequent actions: (a) regulations
which establish a definite requirement for the type of environmental
protection afforded by this device, and (b) production development by
interested manufacturing companies.
2. It is recommended that the additional work include:
a. Establishing data on and improving the reliability of the system
under difficult conditions (high heads, large and irregular holes,
low temperatures)
b. Tests to establish better chemical compatibility data for a
variety of applicator tip membranes under realistic stress-strain
conditions
c. Further low-temperature testing and development
d. An evaluation of cost-benefits of deployment of leak-plugging
systems with three different degrees of proximity to an accident
site (on the vehicle, at the nearest city, and at a central loca-
tion within the EPA region in which the accident occurred)
e. Assessment of the reactions to and requirements of personnel and
organizations which may be using the device
f. Modest field testing and demonstration to personnel from transpor-
tation and emergency response organizations
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SECTION V
DEVELOPMENT WORK
This section describes the evolutionary development work which resulted
in the prototype system delivered at the end of the program. Section VI
describes the final prototype system in detail. There were many concepts
and devices considered and tested during the development program.
Although many of these were later modified or superseded, they are describ-
ed in this section (V) for documentation and for future reference. Some
of these concepts may be useful in future development of leak-plugging
systems for various applications.
BACKGROUND WORK
Most of the exploratory work on the previous project (Ref. 2, 3) used
applicators that placed a polymeric foam directly in contact with the
leaking chemical. Initially, attempts were made to discharge foam direc-
tly from a generator into a hole to plug it. Although this technique
was successful with leaks under very low liquid head, it is totally
impractical when there is significant internal pressure. The velocity
and momentum of a leaking fluid under even moderate driving pressure are
substantial; e.g., for a 1.8-m (6-foot) driving head, the velocity of an
ideal liquid spilling from a hole is about 6.1 m/sec (20 ft/sec); the
horizontal force that must be applied by an operator to hold a plug in
place over a 10-cm (4-inch) diameter hole is about 147 Newtons (33 Ibf).
The next stage in the evolution of an applicator was the use of simple
cup-like structures or an open-ended cylinder with a piston to hold the
foam and to physically force it through a hole against the flow of the
leaking liquid. The feasibility of the concept was demonstrated even
with such simple applicators. Successful leak-plugging tests were per-
formed on 7.6-cm (3-inch) diameter holes in 232-liter (55-gallon) con-
tainers [about 0.9 m (3 feet) of head] with water, benzene, and methanol.
Tests were conducted with leaking containers both submerged in water and
out of the water (Ref. 2, 3).
A number of problems were identified after these early tests. One problem
was the variability in the leak-sealing performance of a given foam and
applicator device. Direct contact between the chemical stream and the
foam, both before and after setting, introduced many variables and
possibilities for failure in the formation of a stable foam and the plug-
ging of the leak. The variations appeared to be the result of complex
interfering actions of the gushing liquid stream against the foam, foam
component composition and mixture ratio, mixing efficiency, initial
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temperatures of the components, ambient temperature, and techniques of
application. Each factor could have an appreciable effect on the leak-
plugging behavior.
It was found to be necessary for the foam to expand both inside and out-
side the leaking container in order to effect a reliable seal. This con-
figuration results in a structural bridge and a secure plug.
Considerable work was done under the previous project (Ref. 2, 3) to
screen and evaluate a number of potential sealant materials. These in-
cluded various urethane foam systems; polystyrene and polyvinyl acetate
instant foams; filled and unfilled epoxy systems; and polysulfide, butyl,
neoprene, and silicone rubber systems. The most-promising results were
obtained with the urethane foams. The better urethane systems, of the
several tested, provided excellent strength and physical properties, good
adhesion to solid surfaces, and satisfactory chemical resistance to a
broad range of hazardous chemicals. The two components of these urethane
systems react to yield crosslinked products, and these crosslinking
reactions are base catalyzed. Acids interfere with the reaction and
attack the crosslinked product. Therefore, some hazardous materials*,
especially acidic ones, can interfere with the curing of a urethane foam
or even attack a cured foam plug.
In this developmental study, it was necessary to consider the range of
practical applications for the leak-plugging device, A preliminary study
was made (Ref. 3) to define an envelope of applicability in terms of
characteristic parameters of a leaking container (size of hole, size of
container, and liquid head in the container) within which leak plugging
should be considered. It is obvious that a very large hole in a small
container will result in a complete loss of the contents before corrective
action can be taken. Therefore, there is an upper limit on rupture or
hole size ( a function of container size, liquid head, and allowable
response time} which it is practical to consider. Another boundary con-
dition arises from considering the practical limits of human strength.
A system that involves stopping the flow of a leaking fluid generally
will require the operator to exert a force sufficient to hold a plug in
place against the hydraulic pressure of the leak for a few seconds. It
was concluded that the region of practical applicability is broad enough
and the potential capability of the leak-plugging system is great enough
to justify its development for operational use. Additional analysis of
the range of practical applications was made during this project and is
described in Section VI, Operating Characteristics, (Characteristic 14).
PRELIMINARY DEVELOPMENT TESTS
The first series of tests made at the beginning of this program were leak
plugging tests with direct application of urethane foam to a chemical
leak (without any restraining or auxiliary hardware). The foam was
delivered to the leak by using a commercially available system (Auto-
froth gun manufactured by 01in Corporation) normally used for producing
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rigid urethane foam for foamed-in-place thermal insulation. This urethane
foam gun was fed frqm pressurized cylinders containing the two foam com-
ponents ,
1. Plugging of holes in an empty container. This was very success-
ful only when the hole was just above a horizontal platform on
which the chemicals could briefly rest while expansion was taking
place.
2. Plugging of holes in a 232-liter (55-gallon) container filled
with water. This was entirely unsuccessful because the foaming
chemicals would not remain in the vicinity of the hole long
enough to form a cured plug. The foam would be swept outward
by the exiting water stream, or, when it did penetrate the water
stream to the inside of the tank, would quickly rise to the
surface of the water in the container due to the very high
buoyant forces exerted by the liquid.
From these tests and testing performed during the previous program (Ref. 3),
it was concluded that the best way to plug leaking chemical containers is
to provide a system where the following sequence of events will take
place:
1. Stop the great bulk of the flow utilizing mechanical means with
assistance from an operator.
2. Introduce foam which expands against the hydrostatic pressure
and is mechanically constrained to prevent movement caused by
buoyant forces.
3, Provide a physical barrier to separate the curing foam from
direct contact with the leaking chemical.
4. Allow time for foam to set in such a way that it provides a self-
locking plug; then the operator can release any required holding
force that he is providing.
5. At some point during the above, the foam should fill all remain-
ing holes (as far as practical), thus providing a tight seal.
Preliminary tests were made of the "expanded-balloon" concept (Fig. 1)
devised at the end of the previous program (Ref. 3). In the foam-filled
balloon concept, an expandable rubber sleeve (or balloon) is attached
securely to the end of a foam supply system. The end of the delivery tube
with the balloon is pushed through the opening in the leaking container.
The premixed foam components are injected into the balloon through the
tube (both through the end and through selected circumferential holes).
As the foam expands, the foam-filled balloon expands on both sides of the
hole to form a mechanical bridge, and this securely holds the plug in
place.
10
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STEP 1.
FOAM COMPOSITE APPLICATOR TIP
INSERTED THROUGH HOLE IN DAMAGED
CHEMICAL TANK
QUICK-DISCONNECT
FOAM
SUPPLY
SYSTEM
^
k-
r-J
1 K
1 l>
1 I
l_.
EXPENDABLE
TUBE SECTION
TANK WALL
LIQUID
CHEMICAL
APPLICATOR
TIP
STEP 2. APPLICATOR TIP, FILLED WITH
FOAM, EXPANDING IN HOLE
FOAM
SUPPLY
SYSTEM
STEP 3. FULLY EXPANDED AND CURED
COMPOSITE FOAM PLUG SECURELY
IN HOLE
Figure 1. Foam-Filled Balloon Concept
11
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A simple version of such a system was constructed in which polyurethane
foam passed through a 1.3-cm (1/2-inch) diameter mixing tube, through a
quick-disconnect, then through a check valve, and finally into the tip of
a rubber sleeve or balloon which surrounded the above hardware. The
rubber sleeve and assembly were then inserted into a round, 3.8-cm (1-1/2-
inch) diameter hole in a tank containing water under 0.6 meter (2 feet)
of water pressure. After insertion, the froth gun trigger was pulled
immediately (for about 5 seconds), filling the rubber sheath with foam
and expanding the sheath so it filled the hole and stopped the main flow
of water.
Good plugs were obtained, although small trickles remained (with leakage
rates of a few cc/min, as compared with several liters/min originally).
This small residual trickle was due to the fact that the foam was restric-
ted inside the rubber sheath and could not expand to conform with all the
irregularities in the edge of the hole. However, this technique, even in
this form, was very effective in stopping the major flow, in providing a
physically strong plug, and in providing a plug that has a barrier
between the tank fluid and the foam, thus greatly reducing compatibility
problems.
There were three difficulties with the expanded-balloon concept. There
was the possibility of tearing the rubber on jagged edges of the hole
before the foam had cured enough to prevent leakage. There was some
difficulty in inserting the collapsed balloon into the hole, since it
lacked rigidity. There was some tendency for the foam to expand pre-
ferentially either inside or outside the tank, rather than both inside
and outside the tank; this was caused by the fluid forces on the foam
before curing. Subsequent applicator development efforts concentrated on
retaining the attractive features of the expanded-balloon concept while
overcoming these three limitations.
Parallel, related development work was devoted to both the applicator and
the foam supply device. Although the work on these two components of the
leak^plugging system" was interdependent, the development of each will be
described separately in the following subsections.
APPLICATOR DEVELOPMENT
The applicator is considered to consist of two elements: an applicator
tip (which places the foam in the opening of the container in a way to
effectively plug a leak) and a handle or probe (which is both a delivery
tube for the foam and a long handle which the operator can use to place
the tip into the rupture while standing some distance away).
The development of an improved applicator went through a considerable
evolution, with many different concepts and variations conceived, built
in simple form, tested, and discarded or modified. An important con-
clusion from this work is that the applicator should provide for complete
or at least partial separation of the leaking chemical and the curing
foam. Various combinations were tested using rubber or plastic bags or
12
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membranes to separate the foam and chemical or using solid, porous, slot-
ted, and other perforated rubber plugs and cones of various types with
foam injected inside and moving to the outside.
The types of applicators devised and tested later in the development pro-
gram greatly reduce or eliminate any compatibility problems between the
urethane foam and the leaking hazardous chemical. This is realized by
inherent features in the applicators which minimize or eliminate any
direct contact between the urethane foam and the hazardous chemical, as
described later in this Subsection* This conceptual improvement elimina-
tes most of the uncertainty and inconsistency previously experienced in
plugging leaks with direct contact between the curing foam and the leaking
chemical.
Before describing various types of applicators which were tested, some
definitions will be made for clarification. The type of flexible poly-
urethane material known commonly as "foam" (used in mattresses and
pillows) is actually a reticulated or open-cell foam (i.e., the cells are
interconnected). This can be contrasted with a closed-dell material
known as rigid polyurethane foam (used for thermal insulation and flota-
tion devices in industry). This closed-cell material is usually produced
at the point of use by mixing two liquid components together. For example,
the urethane foams used in this project consist of a polyol and an
isocyanate, each containing a certain quantity of foaming agent such as
Freon 11 or Freon 12. To distinguish between the two types of foam in
the following discussion, reticulated foam will be referred to as "sponge,"
while closed-cell foam will be referred to simply as "foam."
Expanding Rubber Cone Applicator
This device consists of a truncated cone of solid rubber with a threaded
rod down the axis of the cone, as shown in Fig. 2. Twisting of the handle
forces the two ends together, causing the diameter to increase by as much
as 50 to 100 percent (provided expansion is not restricted).
This device is very effective in sealing fairly round holes, even before
application of a foam. For irregularly shaped holes it cannot, of course,
seal the hole without foam, but it accomplishes two things: (1) it pro-
vides a firm hold on the tank at the hole e4ge sO that a foam-ldispensing
device can be fastened to it to seal the remaining openings around the
edge of the~~hole with foam and (2) it stops a major portion of the flow
through the hole, the amount depending upon the hole shape. Thus, the
initial insertion of this device utilizing a long pole permits immediate
reduction of the main leakage flow.
Two additional versions (Fig. 3 and 4) of the above device were built
which incorporated the use of (1) foam, (2) a thin plastic barrier, and
(3) a plastic sponge. These all combine to fill and stop leakage through
the spaces between the irregular peripheral edge of the hole and the
outer surface of the cone. These features are illustrated in Fig. 3.
The assembly is first forced into the hole and immediately expanded by
13
-------
RUBBER CONE
(A) BEFORE INSERTION
•TANK WALL
WITH HOLE
COMPRESSED RUBBER
CONE
NUT
(B) AFTER INSERTION AND HANDLE
ROTATION (HANDLE REMOVED)
Figure 2. Expanding Rubber Cone Plug
14
-------
CHECK VALVE
TANK
INSIDE
WALL
FOAM INLET
SPONGE AND BAG
Figure 3. Expanding Rubber Cone Applicator (Before Use)
SPONGE
AND BAG
COMPRESSED SPONGE RING
DOME
SPACE TO BE
FILLED WITH
FOAM
CHECK VALVE
-i , FOAM
—' INLET
RUBBER CONE
AFTER COMPRESSION
FOAM AFTER EXPANSION
Figure 4. Expanding Rubber Cone and Dome Applicator (After Use)
15
-------
tightening the nut. This stops most of the flow and locks the rubber cone
in the hole as shown in pig. 3. The foaming mixture is then shot into the
plug using a foam-delivery system (not shown). The foam expands, pushing
the plastic bag and sponge against the inside of the tank and blocking
the openings remaining around the edges of the rubber plug. When the
foam hardens, it furnishes additional strength to the plug system. If
the hole is so extremely jagged that the above is not .adequate, the dome
shown on the right of Fig. 4 is added. The sponge ring is compressed
after the foam has been introduced into the dome but before this foam
can harden. This forces the partially cured foam into the remaining holes
to effect a more complete seal.
A number of minor variations of the expanding-rubber-cone applicator
were tested in an effort to improve the plugging of holes with very
irregular edges (the best of these alternatives is shown in Fig. 3, 5,
and 6). All of the types of rubber-cone applicator tips gave perfect
seals in nearly round holes. Sealing difficulty increased as the ir-
regularity of the holes increased; in even the worst cases, however,
about 98 percent of the flow was stopped. Figures 5 and 6 show a
good sealing test, as viewed from the outside of the tank and from
above the tank wall.
A more sophisticated device using a dome arrangement, as depicted in Fig.
4, was built and used in checkout tests. Operation was easy and leak
plugging was essentially complete (i.e., only a very small leak remained).
The basic hole diameter was about 6.4 cm (2-1/2 inches), with saw cuts
radiating outward about 2 cm (3/4 inch) beyond the outside edge. The
tests were made with water flowing with a head of 1.2 m (4 feet).
The results of this test showed that approximately 90 percent of the flow
was stopped by the rubber cone alone. The remaining flow was reduced by
about two-thirds after the rubber cone was expanded by compression. Flow
was reduced to a small trickle after introduction of the foam into the
rubber cone. Addition of the dome filled with foam on the outside reduced
the flow to about one drop per second.
The above scheme has several advantages from an operational standpoint in
that the plugging process can be divided into stages separated by time
intervals which are flexible and which can be varied in accordance With
the demands of the emergency situation existing irt the field. Thus, only
the rubber cone with mechanical expansion could be initially used to very
quickly stop most or all of the flow immediately. If leakage persisted,
the foam gun would be attached and the bag and sponge would be expanded
with foam on the inside of the tank. Another evaluation period could
then be used to determine whether still more sealing was required. If so,
the dome would be attached, clamped tightly against the tank by tightening
the nut, and the dome subsequently filled with foam, with the possibility
that a complete seal would then be obtained.
16
-------
5DZ16-12/5/73-S1F
Figure 5. Photograph of Plug With Expanding Rubber Cone Applicator
-------
5DZ16-12/5/73-S1C
Figure 6. Photograph of Plug With Expanding Rubber Cone Applicator
-------
The expanding-rubber-cone type of applicator, described in this subsection,
has many attractive features. However, it was not chosen for the final
prototype development for the following reasons:
1. Initial insertion requires a twisting movement of the operator
simultaneously with a thrusting force to hold back the fluid
pressure. This is more difficult than just holding an applicator
in the hole, which requires thrust only.
2. If the device is used underwater, a twisting force may be very
difficult to apply unless the operator has a stationary place to
stand.
3. Tests showed that the dome concept could not be made to seal as
completely as first expected, so the advantage of this method
over the one finally chosen for development was questionable,
while its complexity and cost were much greater.
Toggle and Dome Applicator
This applicator is similar to the expanding-rubber-cone applicator descri-
bed in the preceding subsection in that it attempts to seal the hole by
providing both a plug locked in the hole and a dome full of foam on the
outside.
The toggle is shown extended in the upper view of Fig. 7. The toggle is
first folded parallel to the handle and thrust into the hole to be sealed.
The toggle then opens since it has an internal spring (not shown) which
causes it to extend as soon as it is free of the hole through which it
entered. The operator then pulls on the handle while pushing the dome
toward the hole as rapidly as possible. The first portion of the dome
to contact the tank wall surrounding the hole is a cylinder of polyure-
thane sponge. This material is very easily compressed and will conform
to irregularities in the tank surface surrounding the hole. When the
operator has used his force to press the dome against the tank, he
rotates the dome clamp, thus securing the dome in place.
The foam gun is then triggered (not shown), causing foam mix to flow into
the dome space between it and the thin plastic bag. The foam expands,
pushing the bag and the slip ring ahead of it, and fills the space in the
dome, the form ring, and finally the,hole in the tank. The plastic bag
is finally stretched by the expanding foam into a mushroom-like shape,
thereby locking the foam plug in place and sealing the hole (Fig. 7,
bottom view). The plastic bag serves two purposes:
1. It provides, at least initially, a barrier between the foam and
the liquid in the tank, thereby eliminating possible compati-
bility problems between the foam chemicals and the tank chemicals.
2. It prevents the foam from breaking off and floating to the tank
fluid surface after entering the tank at the hole. Until the
19
-------
COLLAPSED
THIN PLASTIC
BAG
DOME CLAMP
AND HANDLE
LOOSE
SLEEVE
HOLE IN TANK
DOME
SPONGE RING
TANK WALL
(A) BEFORE APPLICATION OF FOAM
ROTATION CLAMPS
DOME TO
HANDLE
LOOSE
SLEEVE
RIGID FOAM
EXTENDED THIN
PLASTIC BAG
FOAM MIXTURE
ENTERS HERE
FOAM NOT SHOWN
HERE FOR CLARITY
COMPRESSED
SPONGE RING
(B) FOAM IN PLACE
Figure 7. Toggle and Dome Applicator
20
-------
foam sets quite firmly, the buoyant forces are sufficient to
break the foam loose from its parent mass. This was avoided in
the previous program by carefully timing the moment of foam
application after the initial mixing of the ingredients. How-
ever, this critical timing requirement is objectionable.
The components of the type of system described above were developed a
step at a time. The dome was first tested without a toggle assembly by
merely requiring that the operator hold the device in place while the
foam was setting. The next step was to build a model having a toggle and
means of clamping the dome to the handle. The model depicted in Fig. 7
was constructed and tested.
The next addition to the design was a means of obtaining a mechanical
advantage for the operator so that he could more easily compress the
sponge rings up against the tank and also to aid in resisting the force
caused by the fluid pressure in the tank. These two forces add together,
tending to force the operator away from the tank. In addition, this per-
mitted the operator to remain further from the tank while performing the
sealing operation without decreasing the maximum tank pressure-hole size
combination which can be sealed due to operator strength limitations.
The operator pushes the dome forward after having secured the toggle
in the hole. When the dome contacts the tank surface, a ratchet is
engaged and the operator squeezes the handle repeatedly, each time advanc-
ing the dome toward the tank by a small distance until the sponge ring is
crushed against the tank sufficiently to stop the major flow of fluid
escaping from the tank. The foam gun is then triggered, activating the
remainder of the sequence which is the same as for the earlier toggle
and dome applicator (shown in Fig. 7).
The drawbacks of this applicator are:
1. Complexity and the associated high cost.
2. Mushrooming of the plastic bag inside the tank is hindered by
the presence of the toggle, especially if it is designed suffi-
ciently strong to hold the pressure forces.
3, The force which the operator must exert can be excessive. The
dome, especially at the critical time of first contact with the
tank wall, will react with a force away from the tank equal to
the average pressure multiplied by the cross-sectional area of
the dome. This force is necessarily larger than the usual force
calculated to stop the liquid flow based on an area equal to the
leak since the dome is considerably larger in area than the leak.
To this must be added the force required to compress the sponge
ring. The operator forces are thus high initially; later, when
the mechanical advantage of the ratchet can be used, the opera-
tor can probably manage this. However, the design, in order to
withstand these forces, becomes too heavy for practical use by
one man.
21
-------
Although the above applicator scheme was not chosen for further develop-
ment during this program, it may be useful in a mechanized scheme for very
large holes where the human strength limitations of a single person are
not a factor.
Solid-Rubber Cone Applicator
This solution to the leak-plugging problem is similar to devices which
have been used for millennia. Sailors historically have used conically
shaped soft-pine cones driven into approximately round holes to stop leaks
in ships and in wooden barrels.
A modern version was constructed of fairly soft, casting-type silicone
rubber. This cone-shaped plug had an apex angle of 15 degrees and was
approximately 25 cm (10 inches) long. It proved to be a very effective
plug for round holes of from 2- to 5-cm (3/4- to 1-3/4-inch) diameter.
The rubber is sufficiently soft so that it can be deformed enough (when
given a hard thrust into a hole) that its re-expansion inside the tank
produces a fairly firm lock. Although very little time was devoted to
this leak-plugging technique, the low cost could make such a passive
method attractive as a "first aid" measure to serve until moi-e sophistica-
ted equipment could be brought to the scene. (For further discussion,
see Section VI, Implementation Plan.)
Foam-Composite Applicators
The most successful type of applicator tip developed during this program
is described in this subsection, and further discussed in Section VI,
Prototype System, and Appendixes A and B. It was found that an uncured
urethane foam (a mixture of the two liquid components) could be forced
into the interconnecting cells of a sponge. The foam flows into the
cells as it expands and cures, thus forming a new composite material
which might be called, for purposes of this report, a foam-reinforced
sponge composite or a "foam composite."
Conceptually, the applicator tips consist of a three-dimensional "spear
head" cut from a large piece of open-celled sponge (Fig. 8). A tube
extends into the sponge along its axis, and has openings through which
the urethane foam is introduced into the sponge interior. There is a
coating or sleeve on the outside of the sponge cone to prevent or restrict
the passage of the leaking chemical into the sponge. The coating or
sleeve has a second function, that of permitting expansion of the end
of the cone to form a plug inside the leaking container and locking the
complete plug into place, as depicted in Fig. 9.
In operation, the applicator tip is pushed into the hole to be plugged.
This causes a large, immediate reduction in the flow of liquid. Then a
valve is actuated (the timing is completely flexible) to start the flow
of urethane foam through the center tube and into the sponge. The
sponge swells both inside and outside the hole (typically swelling to
22
-------
TUBE END IS CLOSED
SPONGE FIRMLY
ATTACHED TO TUBE
•SILICONE RUBBER
COATING ALL SIDES
TUBING
•OPENINGS IN TUBE
TO ALLOW FOAM
TO ENTER SPONGE
OPEN-CELL
POLYURETHANE
SPONGE
Figure 8. Foam Composite Applicator
SILICONE RUBBER COATING
FOAM COMPOSITE (SPONGE WITH
FOAM FILLED PORES)
CURED FOAM
INSIDE TANK
FOAM
INLET
TANK WALL
Figure 9. Foam Composite Applicator After Use to Plug Leak
23
-------
many times the original volume of the sponge). The probe is held in place
while the foam expands and hardens (about 10 to 30 seconds, depending on
the characteristics of the foam used). The final result is a hard plug,
firmly locked in place, which completely, or very nearly so, stops the
leakage of the liquid chemical from the container (Fig. 9).
One of the design considerations is the selection of the covering separa-
ting the the expanding foam composite plug from the hazardous chemical. It
was found that it is important to prevent the leaking chemical from filling
the open cells of the sponge before the foam can be released into the
cells. Otherwise, it is difficult for the foam to displace the liquid (the
combination of internal hydrostatic pressure and surface forces makes the
foam driving pressure to displace the liquid excessively high).
One type of barrier was provided by covering the outer surface of the
sponge with single or multiple coatings of a silicone rubber sealant (as
shown in Fig. 8). After hardening, the silicone coating prevents the
leaking liquid from entering the sponge; yet, when foam is introduced to
the interior of the sponge, the trapped air in the foam can escape outward
since the silicone rubber coating tends to "open" when it is stretched.
This air escape facilitates entry of the foam into the open cells of the
sponge.
An alternative to a semiporous coating is either a completely impermeable
coating or a loose sleeve, as shown in Fig. 10. Tests with the loose
sleeve type of applicator have been very successful, and display an even
broader ability to plug leaking containers than is possible with a sponge
cone along. Figure 10 also shows a check valve in the foam delivery tube;
this feature has been found to be important to prevent the back flow of
uncured foam if the applicator is disconnected from the foam supply system
THIN RUBBER SLEEVE
FASTENED AT ENDS
•SLIGHTLY COMPRESSED
SPONGE
FOAM
INLET
• METAL
PLUG
FOAM DELIVERY HOLES
TUBING
Figure 10. Alternative Foam Composite Applicator
24
-------
before curing is sufficiently completed (quick-disconnect is not shown).
This feature is not necessary in the final design configuration (discussed
in Section VI) since disconnecting is not required until the foam has
hardened.
Adaptation for Underwater Use. For sealing leaking containers under
water, the applicator design was modified slightly to prevent water from
entering the applicator and at the same time to allow air to vent outward
through a check valve as the foam expands on the inside of the applicator
tip. Otherwise, the applicator tip is identical to the one shown in
Fig. 10.
Underwater tests identified a difficulty in seeing the applicator as it
is inserted into a leak. This is due to the lack of visibility caused
by the highly turbulent mixing of the two immiscible liquids right at the
point where observation is required. A simple mechanical stop (discussed
in Section VI) added to the applicator made it possible for the operator
to determine the correct distance by "feel" rather than by sight.
Final Applicator Configuration. The vent and spacer assembly described
above were added to the final configuration resulting in the applicator
design described in detail in Section VI, plus Appendixes A and B.
Applicator Tip for Narrow Cracks
A new applicator tip and operational technique were developed to sucess-
fully plug long, narrow holes. The applicator tip is similar to the- foam-
composite applicator tips described in the previous subsection except
that the sponge is basically wedge-shaped, similar to a pyramid, but with
a blade edge at the tip rather than a point (see Fig. 19 in Section VI).
A plastic bag surrounds the sponge and is sealed to the delivery tube to
provide an airtight seal. A vacuum pump is attached to the delivery tube
and the air is evacuated, causing the outside air pressure to collapse
the sponge into a flat, stiff, triangular shape. The sponge is thus
compressed to a thickness of about 1/20 its former thickness, e.g., from
a 20-cm (8-inch) thickness to approximately 1 cm (0.4 inch) thick. This
compression gives added physical strength to the foam structure, permit-
ting it to withstand the gushing chemical stream that would otherwise
tend to fold over a thin, blade-shaped object.
Tests were made with a crack 1.3 cm wide by 13 cm long (1/2 inch wide by
5 inches long). With the air excluded, the applicator was forced into the
crack while water [under a 1.8-m (6-feet) head] was flowing out of the
hole. The vacuum was then broken, allowing the sponge to expand. Imme-
diately, thereafter, the delivery system was attached and the applicator
was filled with foam in the usual way, resulting in a permanent plug.
Although an electric vacuum pump was used for convenience in this experi-
ment, a small hand-operated vacuum pump was later used on a similar
applicator with a satisfactory vacuum attained after about 5 minutes of
pumping. This time delay probably would be too great for field use.
25
-------
However, methods for obtaining the required vacuum quickly in the field
are possible, e.g., as large-capacity (faster) hand vacuum pump, or pre-
packaging the deflated applicator tip in a vacuum can. Cracks as thin as
0.3 cm (1/8 inch) might be scalable utilizing smaller versions of the
above applicator.
A photograph and description of the final configuration is given in
Section VI (Fig. 19).
Alternate Technique for Very Small Holes and Cracks
Another method for sealing very small holes and thin cracks was devised.
Preliminary tests show it to be promising for, at least, ferromagnetic
tanks.
A patch is first prepared utilizing a semi-flexible backing material
(e.g., fiberglass cloth). A two-part epoxy is then mixed, one part of
which is heavily loaded (80 percent) with iron fillings. A layer of this
rather high-viscosity material is spread on the backing and the patch is
pressed firmly against the hole. The epoxy oozes through the crack and
at this moment a strong magnetic field is applied by simply pushing a
powerful permanent magnet against the patch. The magnetic field immo-
bilizes the epoxy until it has time to harden and it causes the epoxy which
has already passed through the crack to draw backward, forming a mushroom
shape which provides a mechanical lock after the epoxy has hardened. Once
hardening has taken place, the magnet can be removed. The strength of
the seal is thus not dependent upon adhesion to a wet surface as in
ordinary patching methods using epoxy resins.
Other tests were made using an especially fast-setting metal-loaded epoxy
system prepared by the DEVCON Corporation. It sets hard in two minutes.
This technique was not further developed because: (1) the hand-mixed pre-
paration of the epoxy plus harid application of the patch and magnet were
somewhat complicated and possibly hazardous for field use, and (2) the
potential restriction of application to ferromagnetic tanks may prevent
its use in many situations.
FOAM SUPPLY SYSTEM DEVELOPMENT
The foam supply system is needed to deliver urethane foam to the appli-
cator element. This device must provide the functions of storage, trans-
fer, metering, mixing, and delivery of the two Freon-saturated poly-
urethane components, polyol and isocyanate.
Foam Description
The foam utilized in the final prototype is a commercial urethane foam
system and is composed of two parts contained within pressurized cylinders.
One cylinder contains a mixture of hydroxyl-terminated polymers (polyols),
a cure catalyst (a tin salt), and Freons 11 and 12. The other cylinder
26
-------
contains a mixture of an isocyanate-terminated polymer and a diisocyanate,
such as toluene diisocyanate, as well as Freon 12. Volume increase
("foaming") for this system is a function of the volatilization of the
fluorocarbon gas, which is the result of the heat generated by the reac-
tion of the isocyanate ingredients with the polyols. This reaction
(which is both a chain extension and a crosslinking reaction) produces a
matrix of sufficient strength to contain the gas and thus provide a
strong closed-cell foam. If the matrix is weak, gas pressure may rupture
the cell walls holding the gas and produce an open-cell structure.
To obtain a cured product of the proper mechanical strength, the two-
component system must be mixed at the proper stoichiometry and the rate
of reaction must be balanced so that volatilization of the gas and genera-
tion of the crosslinked structure proceed at such a pace that a closed-
cell strong foam results. In commercial applications, this is accom-
plished by matching the viscosity of the two components over the tempera-
ture range from 21 to 32 C (70 to 90 F). It is obvious that temperature
will have significant effect on the rate of reaction, the viscosity of the
ingredients, the volume expansion, and the foam strength. It is also
equally apparent that the present system for plugging leaks should have
as broad a temperature capability as possible.
Approximately six manufacturers of commercial urethane foams were con-
tacted and asked for existing foam formulations that might be suitable
for the present leak-plugging application. From these potential suppliers,
only four viable candidate foam systems (from three different suppliers)
were obtained (see Table 1).
Most of the development and prototype testing was done using the Olin
202-C1 system. This is recommended as a baseline for use with the de-
livered prototypes. The other foam systems were only tested to a limited
extent; however, these tests and the manufacturers' specifications
indicated that they offered no particular advantages over the Olin 202-C1
system.
Foam Hardware Development
A study of the present, commercially available foam delivery systems was
made to determine basic operating principles and the characteristic pro-
blem areas. Several preliminary designs were considered based upon the
commercial units. It was found, however, that the operating temperature
range of commercial foam units was limited to from 24 to 32 C (75 to 90 F).
It was desired to extend this range, if possible, to at least 4 to 38 C
(40 to 100 F).
Tests with commercial units showed that satisfactory operation could be
obtained at 38 C (100 F), but not at 18 C (65 F) and below. Engineering
analysis showed that improvement in the system in two basic areas should
improve low-temperature operation: (1) the mixture ratio should be more
closely controlled, and (2) the mixing intensity should be improved. In
addition, physical size and cost reduction along with improvement in
27
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TABLE 1. URETHANE FOAM SYSTEMS EVALUATED
Manufacturer
M. R. Plastics § Coatings
11460 Dorsett Rd.
Maryland Heights, MO 63043
Midwest Manufacturing Corp.
Oak St. at Bluff Rd.
Burlington, IA
01 in Corp.
P.O. Box 847
Benicia Industrial Park
Benicia, CA 94510
Product Designation
Mistafoam 880-S/800-H
Rigid Urethane Spray Foam
PP-548 Prepolymer
PA-391 Cross linker
*Rigid Polyurethane Spray
Foam No. 202-C1 (sometimes
called Autofroth I chemicals)
Experimental Rigid Polyurethane
Spray Foam No. X- 7- 11 02
("Fast" Foam)
*Material used in final prototype system
reliability would be essential. These improvements were met by developing
rather unique new designs calling for only commercially available, mass-
produced components.
The mixture ratio problem was solved by providing a tandem cylinder (two
pistons on a common shaft) in which the two foam components are separately
stored and are simultaneously expelled at a one-to-one volume ratio using
a positive-displacement technique. The driving force is provided by a
common carbon dioxide gas cartridge. A full description of the final con-
figuration is given in Section VI.
One of the early breadboard models also provided a method of flushing out
the foam chemicals after the system use had been completed so that the
system could be reused without extensive cleanup operations. This capa-
bility is a part of a normal commercial system. It was found, however,
upon studying the system from an overall use viewpoint, that this function
was unnecessary since part of the equipment can be considered expendable.
Thus, any components which require cleanout have been so constructed that
they have become part of the expendable portion of the leak-plugging system.
This decision simplified the delivery system considerably and also reduced
its cost and the logistics problem of supplying the unit with the now
unnecessary cleanout fluid.
A breadboard foam supply device was designed, fabricated, tested, and
improved, it was constructed almost entirely of commercially available
hardware. The developed foam supply system was used for the prototype
leak-plugging system, and is described in detail in Section VI and
Appendix A. The device employs a two-compartment tandem cylinder, a
28
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puncture pin assembly, two pressure relief valves, four valved quick-
disconnect couplings, a mixing chamber, and associated fittings. The two
foam components are stored in separate compartments of the tandem cylinder
until expelled. The tandem cylinder delivers an accurate fixed-volume
ratio of the two components, because a single shaft or rod conniects
separate pistons in each compartment. The driving force for the expulsion
system is provided by carbon dioxide from an ordinary C02 gas cartridge.
The cartridge is housed in a puncture pin assembly which is attached by
gas lines to the tandem cylinder. Prior to using the foam supply device,
the cartridge is punctured, releasing carbon dioxide gas through a small
regulator to a control valve.
When plugging a leak, the operator pushes the applicator tip into the hole
to be plugged and actuates the control valve, allowing the carbon dioxide
gas to feed into the pneumatic portions of the tandem cylinder. This
drives the pistons in unison, thus expelling the fluids from the cylinder,
automatically mixing them, and pushing the mixture into the applicator
element. The entire operation requires only a few seconds.
Mixing techniques were studied and several "static" mixers were tested.
A unique mixing method was finally conceived and developed which gives
good foam production even at low temperatures. The mixing is caused by
forcing a quantity of inert gas into the delivery tube along with the two
foaming chemicals to produce a highly turbulent two-phase flow. With this
gas-mixing technique, the usual static mixer hardware was found to be
unnecessary.
This gas-mixing technique was discovered because it was noticed that
improved mixing was obtained at relatively high ambient temperatures and
that this mixing might be due to increased frothing of the constituents
as they entered the mixer. It was thus logical to try the addition of an
inert gas at low ambient temperatures to create a similar two-phase flow
condition at temperatures where normally insufficient frothing takes place
to achieve mixing. This proved successful during a series of tests using
this technique. The mixing-aid gas is conveniently supplied from the same
pressurant gas supply as is already provided for the tandem cylinder;
i.e., a liquid carbon dioxide cartridge. A small orifice automatically
limits this mixing gas flowrate to the proper value before it flows
through a check valve into the fitting where the two chemical foam con-
stituents come together.
Successful foam delivery tests were made with the entire gas-mixing foam
delivery system as hot as 38 C (100 F) and as cold as 7 C (44 F). A
final test was made where the delivery system was maintained at 18 C
(65 F) prior to use and then suddenly exposed to 0 C (32 F) for a period
of 3 minutes. It was then used to plug a hole at this temperature. No
leaking fluid was used, however, because it was necessary to perform the
experiment in a relatively small cold-box. Good expansion of the
applicator tip was obtained and a normal sealing action was predicted,
had this been done with an actual leaking tank at 0 C (32 F).
29
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CHEMICAL COMPATIBILITY
Early in the program, the leak-plugging concepts under test involved
direct contact between the curing foam and the hazardous chemical that
was leaking. Such direct contact presents formidable chemical compati-
bility problems, because there is much greater danger of chemical attack
on uncured foam and foam components than on the cured foam (which, itself,
is not resistant to all hazardous chemicals). Subsequent development con-
cepts (and the delivered prototype leak-plugging system) incorporate a
barrier between the foam and the leaking chemical (e.g., a plastic or
rubber membrane or coating). Such a barrier provides a large improvement
in chemical compatibility over direct contact between foam and leaking
chemical.
It is anticipated that suitable rubber or plastic membranes can be found
for use with most of the chemicals expected to be designated as hazardous
substances under 40 CFR, Part 116 (Ref 4).. Limited preliminary tests were
made to explore the compatibility of some already available membranes.
Table 2 summarizes results of qualitative experiments made to explore the
compatibility of the Olin 202-C1 polyurethane foam itself, a rubber mem-
brane (composition unknown) in a commercial bag called a "punch ball," a
commercial polyester plastic marketed as "Glad Bags" and an imid-type
polyester plastic material marketed as "Browrt-in-Bag." These four mater-
ials were exposed to six hazardous chemicals representing a broad range
of chemical behavior for static exposures of 40 hours (2 minutes for the
punch ball rubber) at ambient temperatures. It can be seen that the two
plastic membranes had no apparent degradation in any of the chemicals
except concentrated sulfuric acid. This chemical resistance was signi-
ficantly better than the urethane foam and vastly better in organic sol-
vents than the rubber punch ball material. Later tests with neopreme
and silicone rubbers displayed marked improvement over the compatibility
of the cheap punch ball rubber (which was used in early tests merely be-
cause it represented rubber bags of the proper shape and size which were
already commercially available.
Table 3 summarizes results from a later series of compatibility tests. In
these tests, physical properties (i.e., strength and 200 percent elonga-
tion) were tested qualitatively after a 30-minute exposure at ambient
temperature to various hazardous chemicals. It was found that certain
materials designated "compatible" in the commercial literature were found
to be unsuitable for use in this application, mainly because the material
did not retain a great degree of its original strength in elongation.
The results show that the polyester bag material is by far the superior
in compatibility with the six chemicals. However, the advantage of a
rubber membrane is that it provides compression of the sponge in the
applicator, aiding insertion of the applicator into the leak.
The scope of this program did not permit detailed and extensive compati-
bility tests. However, it is believed at this time that a combination
of a neoprene rubber membrane with a polyester-imid resin bag will be
30
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TABLE 2. STATIC COMPATIBILITY OF LEAK-PLUGGING MATERIALS WITH VARIOUS CHEMICALS
HAZARDOUS
CHEMICAL
Methyl
Alcohol
Benzene
NH4OH
(concentrated)
o-Xylene
Sulfuric Acid
(concentrated)
Trichloroethylene
Exposure Time, hr
MATERIAL
Polyester
(Glad Bag)
no apparent
degradation
no apparent
degradation
no apparent
degradation
no apparent
degradation
incompatible,
dissolved
almost imme-
immediately
no apparent
degradation
40
Imid Polyester
(Brown-in-Bag) :
no apparent
degradation
no apparent
degradation
no apparent
degradation
no apparent
degradation
incompatible,
dissolved
almost
immediately
no apparent
degradation
40
Cured Palyurethane
Foam (01 in 202-C1)
specimen saturated with
liquid—possibly some
swell ing-- very spongy
specimen saturated with
liquid— possibly some
swelling — very spongy
some specimen saturation —
rather rigid foam structure
specimen saturated with
1 iqui d; rather ri gi d
foam structure
incompatible, dissolved
forming an orange solution
specimen saturated with
liquid — possibly some
swelling— some rigid
foam structure remaining
40
Rubber
(Punch Ball)
no visible
degradation
noticeable
swelling
small bubble
formation
noticeable
swelling
noticeable fading
of blue color to
light green, then
to brown slowly
noticeable
swelling
2 min
-------
TABLE 3. EFFECTS OF HAZARDOUS CHEMICALS ON PHYSICAL PROPERTIES ON
LEAK-PLUGGING MATERIALS
Hazardous
Chemical
Methyl Alcohol
Benzene
NH4OH
o-Xylene
Sulfuric acid (98%)
Trichloroethylene
Performance of Leak-Plugging Material*
Neoprene Rubber
(Medical Type)
Poor
Poor
Good**
Poor
Poor
Very Poor
Neoprene Rubber
(Glove Type)
Satisfactory
Poor
Good**
Poor
Poor
Very Poor
Polyester
("Glad Bag")
Good**
Good**
Good**
Good**
Poor
Good**
Polyester-Imid
("Brown- In-Bag")
Good**
Good**
Good**
Good**
Poor
Good**
Cured Poly-
urethane Foam
(Olin 202-C1
Poor
Poor
Satisfactory
Poor
Poor
Poor
CM
NJ
*Retention of Strength and Elongation after 30-Minute Exposure
**Essentially unaffected
-------
sufficiently compatible to allow leak-plugging of virtually all of the
important hazardous chemicals.
TEST FACILITY
Two special test facilities were constructed during the program to make
expeditious testing possible (Fig- H)- Both had a common feature con-
sisting of a large pipe flange (20-cm (8-inch) pipe for the small facility,
and 30-cm (12-inch) pipe for the large facility) placed near the bottom
but on the side of the tank and connecting with the inside of the tank. A
flat plate and gasket were bolted to the flange, closing off the hole just
as in a standard blind flange installation. A hole was cut or punched in
the plate, simulating an accidentally made hole in a tank wall. The
plates were usually made of 1.3-cm (1/2-inch) thick acrylic sheet, but
were occasionally made of 0.3-cm (1/8-inch) thick steel or aluminum.
Various plates were made having different hole sizes and shapes. The
transparent plates made possible very convenient observation of the
expansion taking place inside the tank wall during the test. The remova-
ble plates were also convenient for photographing the results and for
close inspection of a completed plug after removal from the hole.
This facility enabled tests to be made in a relatively rapid sequence
because the plate was removed at the end of a test along with the plug
which had been formed in the hole; then a new plate was substituted and
the facility was ready for another test. In addition, the large facility
had a remotely operated butterfly valve in the pipe section between the
tank and the plate. This valve permitted convenient filling of the tank
prior to a test and was opened only a few seconds before a test was begun.
The valve was closed again before removal of the plate and plug, and the
liquid "lost" was pumped back into the tank. This facility also was
equipped with a 600-gallon catch tank so that chemicals lost through the
leak just prior to plugging could be caught and reused, thus saving a
disposal and procurement cost, preventing an environmental problem,
avoiding materials delivery delay, and permitting an estimate to be made
of the quantity spilled before plugging was completed.
33
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Figure 11. Test Facility in Use
-------
SECTION VI
PROTOTYPE SYSTEM
This section describes the prototype leak-plugging system which was de-
veloped during and delivered at the end of the program. Appendix A con-
tains detail design drawings and a parts list for the delivered prototype.
Appendix B gives detailed instructions for refilling the foam delivery
system.
SYSTEM DESCRIPTION
The basic principle of the delivered prototype leak-plugging system is
illustrated in Fig. 12. The system consists of a foam supply device (pres-
surized cylinders plus control and mixing elements shown on the left of
Fig. 12), and an applicator (shown on the right side of Fig. 12) which
places the foam in the hole to be plugged in an effective way to seal the
hole. The applicator has a handle with an actuating device on one end and
an applicator tip on the other end.
The tip is thrust into the hole to be plugged and the delivery system is
activated by the operator. This causes two urethane foam components to be
released from their pressurized containers, automatically mixed together
as they flow, and forced into the applicator tip while it is being held in
the hole (partly inside the container and partly outside the container).
Expansion of the foam causes the applicator tip to expand both inside and
outside the tank wall simultaneously, filling the hole and stopping the
leak. About 2 minutes after the start of this expansion, the foam has be-
come hard enough to permit removal of the handle and the delivery tube; the
plug is then self-supporting. Ninety percent of full strength is reached
after another 5 to 10 minutes, depending upon the temperature; some addi-
tional strength is gained during the subsequent hour or so.
The delivery system then can be disconnected, recharged with foam compo-
nents, and attached to a new applicator (in the field), rendering the sys-
tem ready for a repeat plugging operation, if required. This repeated use
can continue over many cycles. However, after the period of emergency use
in one incident, the leak plugging system should be carefully cleaned and
refilled, to ensure reliability during its next emergency use. This ser-
vicing might be set up on an exchange basis with the manufacturer, return-
ing the fired unit to the factory for cleaning and refilling in exchange
for a previously serviced unit. It should be possible to store a factory-
serviced system for periods of a year to possibly several years (storage
life tests will be needed to establish safe periods), depending upon pre-
cautionary details called for and carried out in the construction, design,
and storage of the delivery system.
35
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CHEMICAL
TANK WALL-
QUICK-
DISCONNECT
/•
LIQUID
CHEMICAL
*//
U
PRESSURIZED FOAM
COMPOUND CYLINDERS
EXPENDABLE
TUBE SECTION-
STEP 1. FOAM COMPOSITE APPLICATOR TIP
INSERTED THROUGH HOLE IN
DAMAGED CHEMICAL TANK
NT
APPLICATOR'
TIP
FOAM
SUPPLY
STEP 2. APPLICATOR TIP, FILLED WITH FOAM,
EXPANDING IN HOLE
STEP 3. FUL-tY EXPANDED AND CURED
COMPOSITE FOAM PLUG
SECURELY IN HOLE
Figure 12. Basic Concept of Prototype Leak-Plugging System
36
-------
The urethane foam system used as a baseline is Olin No. 202-C1. Other
foam systems may give equivalent performance, but should be tested before
selection.
Rigid polyurethane foams are formed by the reaction of certain isocyanate
compounds with hydroxyl-bearing polyols which, when mixed together in the
presence of a catalyst and other additives, chemically react to form multi-
branced polymer chains.
In the process of forming the foam, the two basic components are pressur-
ized in separate cylinders with an extremely low boiling fluorocarbon and
are fed through a static mixing chamber, in a controlled ratio, and then
expelled. The sudden decrease in pressure during expulsion at the mixing
chamber causes the low boiling fluorocarbon to volatilize, thus creating a
froth material very similar to aerosol shaving creams. This material fur-
ther expands as the heat generated from the chemical reaction of the iso-
cyanate and polyol causes the continued expansion of the fluorocarbon gas
until finally, in a relatively short period of time, the polymer has ob-
tained sufficient strength to withstand the pressures of the expanding gas
and the material completes its rise and starts the curing process. The
final product is a homogeneous cellular material comprised of many tiny
closed cells, each containing some of the fluorocarbon gases.
PNEUMATICALLY OPERATED DELIVERY SYSTEM
Figures 13 and 14 show the pneumatically actuated delivery system. A com-
plete set of design drawings and a components parts list are given in
Appendix A. The part numbers in the photos, the drawings, and the parts
list are all consistent.
The largest component is the tandem cylinder (No. 40 in Fig. 14), which
contains polyol (Chemical B) in the right end and isocyanate (Chemical A)
in the left end. On the other side of both pistons is a space into which
the carbon dioxide pressurant gas is conducted. This gas comes from a
small carbon dioxide cartridge (2), through a puncture pin valve (1),
through a pressure regulating valve and gage (3), through a normally closed
pneumatically operated valve (6), and into the two tandem cylinders.
The tandem cylinders are initially filled with chemicals through two quick
disconnects (35 and 36), causing the pistons to rest in their left-most
position with maximum protrusion of the external shaft to which the two
pistons are connected. When the operator causes valve 6 to open, the car-
bon dioxide gas forces the two tandem pistons to the right, expelling the
two chemicals simultaneously through pressure relief valves (33 and 34)
that are set at 120 psi, then through quick disconnects (37, 38, and 104),
and into the mixing cross (101) where they are joined by a flow of mixing
gas which aids in delivering the mixed chemicals down the flexible de-
livery tube (120) and into the applicator tip. (Parts 101, 104, and 120
are shown in Appendix A.)
37
-------
APPLICATOR
ACTUATION
CONTROL
PIPING SCHEMATIC
Figure 13. Schematic Diagram of Pneumatically Operated
Prototype Foam Delivery System
38
-------
5AG31-1/13/75-S1A
Figure 14. Pneumatically Operated Prototype Foam Delivery System
-------
The mixing gas, also carbon dioxide, is obtained at a specific flowrate
from the single pressurant supply (2) through a carefully adjusted bleed
valve (8), which also contains a check valve, through the quick disconnects
(39 and 103) and into the cross (101), where the mixing takes place.
Actuation of valves 6 and 7 is caused simultaneously when the operator
turns valve 5 to the actuate position. This allows carbon dioxide pres-
surant gas to flow through pressure-regulating valve 4, which is set at
70 psi, to the actuators on valves 6 and 7. Valve 7 is normally open, in
contrast to valve 6, which is normally closed. Application of the actua-
tion gas causes the vent to close and the pressurant gas valve to open
simultaneously. When the operator has decided that all the chemicals have
been expelled from the tandem cylinder, he reverses the position of actuat-
ing valve 5, causing a reversal of the positions of valves 6 and 7, which
allows the pressurant to vent from the tandem cylinders and shuts off the
pressurant supply simultaneously, thus stopping the flow of chemicals.
The actuation period (the length of time that the operator holds valves 5
in the actuate position) is usually about 10 seconds but is not critical
as long as it is held open about 5 seconds or more after the tandem piston
has reached its extreme, full-expulsion, position. Once the pressurant
has been vented, the tandem pistons usually return to the left a small dis-
tance due to the pressure exerted by the small amount of chemicals not ex-
pelled during actuation. (This is of no consequence.) The actuation
stroke of the pistons is automatically limited by the mechanical stops in
the cylinder. A partial expulsion can be easily obtained by providing a
mechamical stop for the piston in the form of a short piece of metal tub-
ing around the protruding shaft. (This feature has not been included in
the delivered design.) Again, it is important to realize that the operator
is not required to make careful judgments about the length of time to leave
the actuation valve open; he merely needs to leave it open for at least a
few (say 5) seconds beyond the end of piston movement.
Once the flow of chemicals from the tandem cylinders has stopped, the pres-
sure relief valves (33 and 34) automatically close and then act as check
valves, preventing the expanding foam in the mixing cross (101) and de-
livery tube (120) from flowing backwards into the tandem cylinder. The
check valve incorporated into mixing gas bleed valve (8) serves the same
function for the pressurant gas system. The flexible tubing (119) between
parts 103 and 101 serves to catch any expanding foam coming backward from
the mixing cross. The applicator tip and all components down to and in-
cluding the quick disconnects (103 and 104) are expendable for each plug-
ging operation and are consequently allowed to fill with expanding foam.
However, system design should provide that no foam reaches the permanent
quick disconnects attached to these (parts 37, 38, and 39), since they are
part of the permanent delivery system and may be called upon to be reused
before a major servicing. Any foam which has set up in them will render
them temporarily useless until cleaned or overhauled. On the other hand,
the neat foam components (i.e., unmixed with the other) are not harmful to
the quick disconnects, except that the disconnects that are exposed to
40
-------
isocyanate (36 and 38) for 3 hours or longer will become more and more dif-
ficult to operate because of the reaction between this material and the
moisture in air. Should the delivery system be required to be actively used
for a time period exceeding 3 hours, then a "first-aid" type of maintenance
should be performed consisting of flushing these two components with a sol-
vent to remove excess (and exposed) isocyanate.
To reuse the delivery system, the tandem cylinders are refilled as described
in Appendix B; a fresh carbon dioxide cartridge (2) is substituted for the
expended one. The old mixing and delivery system (101, 103, and 104) is
removed and a fresh applicator assembly is attached; first, the applicator
tip is attached to the handle and then the quick disconnects are attached
to the delivery system. The system is then ready to perform another plug-
ging operation.
A pressure relief valve (50) is provided for safety purposes. Should the
pressurant gas exceed 250 psig, then this valve will automatically relieve
the pressure by venting the excess. This ensures that no damage will re-
sult if the main regulator valve (3) should fail or if the operator should
set the pressure at too high a level.
MECHANICALLY OPERATED DELIVERY SYSTEM
A second prototype system was delivered (Fig. 15) which includes a foam
delivery system very similar to the pneumatically operated delivery system
just described. The only significant differences are in the tandem cyl-
inder size and in the method for activating the flow of foam.
A mechanical actuating means is provided in the system shown in Fig. 15 by
substituting a control cable for the pneumatic tubing and the pneumatic
actuation components used in the other prototype (Fig. 14). To achieve
actuation, the operator moves a lever at the handle end of the control
cable (Fig. 15). This pulls down a hinged bracket against the button *of
a three-way palm button valve. (For design details, see note 8 of the
component specification list in Appendix A.) This three-way valve serves
the same function as the two pneumatically operated valves (6 and 7) de-
scribed in the previous section, i.e., it closes off a vent port and opens
a passage to allow the pressurant gas to pass from the pressure regulator
into the tandem piston, causing it to actuate. Part of this gas is also
conducted through the mixing gas bleed valve (8) into the mixing cross
(101).
The mechanical system requires fewer commercially available components than
the pneumatically operated system, but requires a greater number of speci-
ally fabricated brackets and levers. The costs of the two prototype sys-
tems are not significantly different. The mechanical system has a modest
weight advantage relative to the pneumatic system. Systems with fewer
components usually have increased reliability; however, pneumatic systems
are usually inherently more reliable than their mechanical equivalent. The
overall reliability of the two systems should be expected to be approxi-
mately equivalent. However, in development testing of the two prototype
41
-------
—
• J
5AG31-1/13/75-S1C
Figure 15. Mechanically Operated Prototype Foam Delivery System
-------
systems, it was found that the pneumatic actuation system was slightly
more reliable.
Both the pneumatically and mechanically actuated leak-plugging systems are
practical and there is not a large difference, overall, between them. How-
ever, the pneumatic actuating system is recommended since the increased
reliability is considered to be an essential advantage in a leak-plugging
system which will be used or tested relatively infrequently and which will
be used in an inherently dangerous environment where equipment reliability
has a high premium.
APPLICATOR
The prototype applicator is shown in Fig. 16; detail drawings and a parts
list are given in Appendix A. The operating principle of the foam compos-
ite applicator chosen for the prototype was also discussed in Section V
and further illustrated there in Fig. 8 through 10. The main structural
member of the applicator is the metal delivery tube running in the center
between the long, flexible delivery tube on the right and the applicator
tip on the left. The U-shaped, dark-colored piping in the center is the
spacer subassembly. It is adjustable; movement can be obtained forward
and back by sliding it up and down the metal delivery tube after loosening
the hose clamp surrounding the short piece of split tubing at its center.
The function of the spacer is to give the operator an automatic stop
against the side of the tank when the applicator tip is inserted into rhe
leak, thus eliminating operator judgment and skill in the in-and-out posi-
tioning of the applicator during a leak-plugging operation.
In Fig. 16, the transparent vent tube can be seen protruding from the right
end of the applicator tip. This -tube allows air inside the tip to escape
as displaced by the foam entering at the center, and reduces the back pres-
sure which would otherwise be generated by the trapped air.
After the tip has been inserted into a hole up to the end of the spacer
prongs, the operator actuates the delivery system. This causes mixed chem-
icals and carbon dioxide mixing gas to flow rapidly through the flexible
hose and metal delivery tube, and then into the applicator tip through
holes in the metal delivery tube. Most of these exit holes are at the very
tip of the applicator, while only two are near the vent tube end (details
are given in the Appendix A drawings). The positioning of the exit holes
allows foam chemicals to enter the applicator tip through its length.
Figure 17 shows an expanded applicator tip after plugging a hole approxi-
mately 6.1 cm (2-1/2 inches) across under a water head of 3 meters (10
feet). The jagged hole was cut in a clear plastic plate for ease in view-
ing. Figure 18 shows a similar expanded applicator tip, sectioned for
viewing.
After the foam is set, the handle can be easily separated from the appli-
cator tip by loosening the thumb screw at the tip of the handle. The long
applicator hose can be removed by simply cutting the foam-filled hose with
a pair of diagonal cutters or a knife.
43
-------
5AG31-1/13/75-S1D
Figure 16. Prototype Applicator
-------
V'.
Figure 17. Prototype Applicator After Plugging
-------
o
Figure 18. Sectioned Prototype Applicator After Plugging
-------
The present prototype design requires that the given mixing assembly be
used with a given tandem cylinder size, i.e., it is not interchangeable
between large and small prototypes (see note 2 of the parts list). How-
ever, the tips are easily detached, and any tip can be used with any mixing
assembly.
Applicator for Cracks
Some development also was done on a special version of the foam composite
applicator for use in plugging long narrow holes (e.g., cracks). Figure
19 shows a prototype of the special applicator tip. This particular tip
is sized to plug cracks wider than approximately 1.3 cm (1/2 inch) and up
to about 15 cm (6 inches) long. The use of several such tips side by side
will permit plugging of very long cracks.
The applicator tip, although shown to be about 20 cm (8 inches) thick in
Fig. 19, is compressed to only about 1 cm (0.4 inch) thick by evacuating
the space within the transparent plastic bag. The outside air pressure
collapses the central sponge into a flat, spear-head-like shape. The metal
delivery tube runs all the way to the tip and is flattened at the end to
permit easy entry, along with the sponge, into the crack. Once the tip is
inside a hole, the operator breaks the vacuum by connecting the quick dis-
connect on the upstream end of the rubber hose to the mixing assembly
(shown at X in the upper middle of Fig. 1?), and thus connects it to the
foam delivery system. The quick-disconnect contains a spring-loaded check
valve that opens when the quick disconnect is connected. This action
allows the flow of foam chemicals into the rubber delivery tube and on
into the applicator tip. The stopper is removed from the long vent tube
to permit the mixing gas to escape to the atmosphere, relieving the back
pressure inside the applicator caused by the entering foam chemicals. In
its present state of development, this applicator is more difficult to use
in a leak-sealing operation than the normal applicator. Further develop-
ment is needed to simplify its use.
METHODS OF USE
*
Figure 20 shows the complete mechanically actuated prototype leak-plugging
system with the foam delivery system mounted on a standard backpack frame,
and with the operator holding the applicator tip and handle attached to
the delivery system ready for use. Although the mechanical system is shown
in Fig. 20, a simple substitution allows mounting the pneumatically actu-
ated system in an identical way.
It has been found from experience that a convenient alternate method is to
carry the system like a suitcase in one hand to the spill site and then to
lay it on the ground next to the operator at the site of the leak. The
backpack configuration can be used in this way, using one of the side sup-
ports of the rack as a handle. Figure 14 shows the pneumatically actuated
prototype mounted on a flat plate with a handle, in lieu of the rack.
Wearing the backpack will be an advantage where the operator must use both
hands to climb a ladder or similar function, while carrying the applicator
47
-------
CO
Figure 19. Prototype Applicator for Cracks
-------
Figure 20. Back-Mounted Leak-Plugging System Ready for Use
49
-------
handle at the same time. On the other hand, if crowded quarters must be
entered, the rack may snag on protruding structural members, in which
case, carrying the delivery system by hand at the operator's side may be
preferable. Mounting the delivery system on the chest of the operator
instead of on his back also might be advantageous in extremely restricted
areas.
Operation
The use of the leak-plugging system is illustrated in Fig. 21 through 26
(which show photographs of a leak-plugging sequence from the development
testing), and is discussed in this subsection.
The component subassemblies are first removed from their storage place in
the emergency vehicle. Protective clothing, if required, is put on except
for the helmet. A carbon dioxide cartridge (2) is screwed into the place
provided for it. The lanyard is pulled to puncture the C02 cartridge.
The pressure is checked on the pressure gage to see if it is at 250 psig.
If not, the regulator knob is turned until the pressure is 250 psig.
Once the lanyard has been pulled to puncture the carbon dioxide supply
cylinder, the lever attached to the lanyard should be placed back in its
resting position prior to activation to ensure that the piston rod, during
later actuation, will not strike against the lever and break the puncture
pin assembly housing. Should this happen, the assembly will have to be
replaced. A simple design change can be made in subsequent models to
eliminate the need for this precaution.
An applicator tip is selected and attached to the handle. The quick dis-
connects on the mixer subassembly are plugged into their mates on the de-
livery system. The unit is placed, on the operator's back and the helmet
is donned; the handle is then picked up (Fig- 20). The operator then
walks up to the leak (one from the development test facility shown in
Fig. 21), approaches it from the side and thrusts the end of the appli-
cator into the hole until the ends of the spacer contact the tank surround-
ing the hole (Fig. 22). The axis of the applicator tip need not be at a
right angle to the tank surface surrounding the hole. The operator im-
mediately turns the valve at the end of the handle, causing the delivery
system to fill the applicator tip with the foam-producing mixture. The
foam begins to expand the applicator tip rapidly, both inside and outside
the tank wall. Typically, most of the leak is stopped within about 10
seconds (Fig. 23). The foam expansion is complete in about 30 seconds,
with maximum tank sealing (Fig. 24 and 25). An applicator tip, expanded
on both sides of the tank wall, forms a tough, rigid plug that is locked
in place (Fig. 26).
During foam delivery and for about 2 minutes afterward, the position of
the probe should be held as steady as possible against the pressure of the
outrushing tank fluid. Once the plug is hard, the handle is undamped and
laid aside. A knife or pair of diagonal cutters is then used to cut the
long delivery hose. The operator picks up the handle, moves back a safe
50
-------
Figure 21. Gushing Liquid Leak in Test Facility
Figure 22. Applicator Just Inserted Into Leak
51
-------
Figure 23. Leak Slows as Applicator Expands
Figure 24. Leak Stopped by Full Applicator Expansion
-------
Figure 25. Close-Up of Completed Plug
Figure 26. Completed Plug After Removal From Tank
-------
distance to where the balance of the leak-plugging equipment has been
placed, and repeats the procedure above using a new set of equipment or
refilling the delivery system with foam chemicals and installing a new
applicator tip. A description of the refilling procedure is given in
Appendix B.
The prototype delivery systems are intended as one-shot devices before
recharging with foam chemicals. Similar systems could be constructed with
large cylinders and used to plug more than one hole before delivery sys-
tem must be refilled. Such a large system would use a series of mechan-
ical stops to limit the travel distance of the pistons during each shot.
This stop would have to be repositioned by the operator after each shot.
Post-Operation Considerations
The life of the installed plug depends upon a number of factors. A de-
sign goal for this program was to provide a life of approximately 24 hours.
Actual life of plugs when the prototype systems are used will probably be
much longer than this if chemical compatibility is not a problem; i.e.,
it is expected that plug life will depend upon chemical compatibility
considerations rather than upon mechanical or physical factors.
Should it be essential, the protruding metal delivery tube and spacer sub-
assembly can be cut away with a hacksaw after allowing about 1/2 hour for
the plug to -attain maximum structural strength. However, unnecessary and
forced straining of the plug is not desirable, since the foam is somewhat
crushable and only slightly elastic. If the crushing strength of the foam
at the ragged edge of the hole were exceeded by some externally applied
force, then increased leakage would be likely. Thus, if movement is
forced, usually any leakage remaining will be increased. Therefore, any
unnecessary cutting, handling, or manipulating of the plug should be
avoided. On the other hand, the foam, once cured, is very strong and
rigid if the plug has been properly formed. For example, the protruding
parts of completed plugs have supported the weight of a man without major
damage.
OBSERVATIONS FROM PROTOTYPE TESTING
The final prototype gave very satisfactory performance in plugging leaks
of various sizes and under a variety of conditions. Additional work is
needed to further improve its reliability and repeatability when used in
more difficult cases (e.g., with very high liquid heads, large -holes, or
at low temperatures).
Demonstration tests were made and filmed (Ref. 5) with the prototype
nearly in final form. Subsequently, the spacer subassembly (shown in
Fig. 16) was added to the applicator near the end of the program. This
feature was of considerable help in eliminating much operator skill and
judgment in positioning the applicator tip in the leaking hole.
54
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Some other observations and suggestions for the prototype user are briefly
outlined in the remainder of this subsection. A detailed description of
the prototype capabilities and operating characteristics is given in the
next subsection.
The reliability of obtaining a good seal decreases as the head pressure
increases, not only because of difficulty experienced by the operator in
holding the applicator in the hole against the internal tank pressure,
but also because of the reduced volume of foam obtained when it is forced
to expand against a higher tank pressure.
It is estimated that the quantity of foam required increases roughly as
the cube of the hole diameter. Thus, the size of the applicator tip and
quantity of foam chemicals delivered to the applicator tip ideally should
be changed somewhat for large variations in hole size.
At low temperatures, there is a tendency to deliver a smaller volume of
foam, other factors being equal. The exact relationship is not simple,
however, since temperature effects are also related to mixing and foam-
curing effects which help but are difficult to quantify. This complicated
contribution of mixing and curing occurs because the foam mixture, once
well mixed even though cold, soon warms because of the exothermic char-
acter of the reaction between the two chemicals and their inherently good
insulating qualities. Even a slight amount of reaction will generate heat
and raise the temperature slightly, which in turn will strongly increase
the reaction rate, producing even more heat, etc. This exothermic process
ultimately causes a very rapid reaction and rapid foaming. Although this
mechanism requires a longer time to start at low temperatures, once
started the reaction proceeds to completion and the temperature inside the
foam appears to be not greatly different from that obtained by starting
with the chemicals at normal temperatures, provided, that the two chemi-
cals are well mixed.
There is an important factor which permits mitigation of the requirement
for having a precise amount of foam delivered to the applicator tip, de-
pending upon the hole size, head pressure, and chemical temperatures.
This factor is that the final size of the expanded applicator tip reached
at the end of the plugging operation can be far greater than is necessary
without causing any problems. Having far too great a quantity of foam
does not hurt the quality of the seal; having too little, of course, pre-
vents successful leak plugging. Therefore, the quantity of foam should
always be set to be the maximum allowable and limited only by the size and
elongation of the outside membrane of the applicator. Having the outside
membrane burst, either inside or outside the tank, is almost always unde-
sirable since it allows the tank fluid to come into contact with the foam.
55
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OPERATING CHARACTERISTICS
Particular attention was given during the prototype development work to
considerations of safety, ease of use, lightness of weight, rapid-response
capability, and other features that are important in a practical opera-
tional system. These goals and corresponding capabilities of the proto-
type are discussed in this section.
A broad range of goals for system operating characteristics were listed
at the beginning of this effort to serve as guidelines for prototype sys-
tem development. These goals are as follows:
1. No external power requirements
2. No secondary pollution problems
3. Allows salvage of hazardous chemical remaining in tank
4. Permanent or long-term plugging
5. Rapid response
6. Usable with dry, dirty, and wet surfaces
7. Moderate weight and portability (use by one man)
8. Long shelf life
9. Reasonable cost
10. Compatible with wide range of hazardous chemicals
11. Ability to completely plug leaks
12. Safe and easy to use by untrained personnel
13. Flexibility in hole size, shape, location, etc.
14. Usable with liquid heads as high as those encountered in tank
cars
15. Wide temperature tolerance (both in storage and application)
Each of these goals has been achieved, at least to a sufficient extent to
permit satisfactory use of the prototype leak-plugging system. The indi-
vidual goals and corresponding system characteristics are discussed in the
following subsections (numbered according to the list of goals above}.
1. No External Power Requirements. The system is completely port-
able and self-contained. Only a small cartridge containing
liquid carbon dioxide is required to perform the tasks of de-
livering and mixing the two foam chemicals. The standard cart-
ridges are widely available in wholesale or retail stores, inex-
pensive, and weigh only a couple of ounces.
2. No Secondary Pollution Problems. Absolutely no secondary pollu-
tion problems are caused by the leak-plugging system. This is
further discussed under subsection 3 below.
56
-------
3. Allows Salvage of Hazardous Chemicals Remaining in the Tank.
This leak-plugging system stops the leakage of the chemical, thus
retaining it in the original tank. No foreign materials (e.g.,
gelling agents) are introduced into the chemical. The present
system inherently does not contaminate the chemicals in the tanks
because the applicator membrane forms a barrier between the haz-
ardous chemical and the urethane foam. If the chemical resist-
ance of the membrane is adequate through the period of leak plug-
ging, i.e., is not attacked or dissolved by the chemical, then
there will be no contamination of the chemicals in the tank.
Even in unusual cases where there is some failure of the membrane,
there may be at most very minor quantities of urethane foam or
rubber membrane material introduced into the tank.
4. Permanent or Long-Term Plugging. In an emergency, any kind of
even very temporary plugging of a hazardous chemical leak is
welcomed, provided it is not dangerous to implement. Thus even
a plug lasting 1 or 2 hours might be vital in an emergency, were
it available. With the prototype system, the life of a completed
plug is variable, depending almost entirely on the chemical com-
patibility of the applicator tip membrane. In general, the life
will easily achieve the 24-hour time requirement set as a goal,
depending upon the compatibility of the membranes utilized with
the particular chemical leak that is being sealed. By appro-
priately choosing the proper membranes, the plug may last up to
weeks or months.
In those cases where adequately inert membranes cannot be found
to achieve at least a 24-hour life (which is true for only a
few chemicals), there may still be obtained a life of a few hours.
Even a reduced period will provide time to take other action.
5. Rapid Response. A minimum response time is, of course, desired.
The present system has a response time close to the minimum of
any imaginable which is still practical. Arrival at the site
with corrective gear and personnel as soon as possible after dis-
covery of the leak is important. The present equipment is small
and inexpensive enough so that many units can be appropriately
placed on actual transportation vehicles (trucks, trains, ships)
or in local fire stations. The response time is reduced greatly
as the number of systems that can be deployed is increased.
The second part of the response time is that required to plug the
leak after arrival at the site. This is made up of times to un-
pack equipment from the vehicle, dori protective clothing, and
perform the actual leak plugging. Present estimates, based on
testing with the prototype during this program, assign the fol-
lowing times to these steps (assuming that the leak-plugging
system and an operator who is familiar with the system are at
the site in advance)
57
-------
Unpacking equipment 30 to 60 seconds
Donning protective clothing 40 to 60 seconds
System adjustment and moving to leak 20 to 60 seconds
Plugging of the leak 50 to 50 seconds
Total 2 to 3 minutes
These times could vary considerably, depending on location of the
leak and damaged tank, weather conditions, operator experience,
etc. In any case, the total time for use of the equipment is
short compared with the time required for arrival at the site.
6. Usable With Dry, Dirty, and Wet Surfaces. The system does not
depend at all on the adhesive qualitites of materials to achieve
a seal. Rather, it depends on the shape and rigidity of the ex-
panded applicator tip to maintain an adequate plug. Therefore,
the condition of the tank wall surface is totally unimportant.
7. Moderate Weight and Portability. One man can deploy, mount, and
use the prototype system by himself. However, it is desirable to
have a second individual standing by at a relatively safe dis-
tance to observe the operator, in case of an emergency in which
the operator may need help. If a second individual is available,
he also can speed up deployment and mounting of the equipment.
The actual leak plugging should be a single-man operation (which
also reduces the total risk exposure).
8. Long Shelf Life. The shelf life of the delivery system is prim-
arily determined by the storage life of the foam components and
the long-term compatibility of those chemicals with the seal
materials in the delivery system. Long-term storability tests
should be a part of the production development effort. A period
of 6 months to 2 years between equipment servicing appears to be
a reasonable expectation.
The estimated shelf life of the applicator tips is limited only
by any deterioration of the membrane materials. Ozone can de-
grade some rubber membranes rapidly. Long-term shelf life should
be one of the factors in final membrane material selection.
Applicator tips might be stored in the field in sealed containers
under a slight positive pressure of dry nitrogen or other rela-
tively inert gas. The "crack-type" applicator should be stored
in an evacuated tubular container.
9. Reasonable Cost. The estimated costs to duplicate the delivered
prototype leak-plugging system are given below (at 1974 prices).
Material costs are actual costs taken from the fabrication of the
prototype during this program; labor costs are estimates for a
batch production run of 50 systems.
58
-------
Foam delivery system (mechanically operated prototype):
Material $304
Labor $400
$704" $704
Applicators:
Material $ 31 each
Labor $ 25 each
|~56"
Three applicators at $ 56 each $168
One handle at $ 8 each $ 8
Storage container $ 20
Total direct cost (not commercial sales price) $900
It is expected that the cost to fabricate production models,
after a production development program, could be considerably
lower than the figures above.
Equipment for refilling the foam delivery system in the field
will cost approximately $150 each to fabricate, plus chemicals.
The foam components cost about $100 commercially for a pair of
cylinders containing a total of approximately 45 kg (100 pounds)
of chemicals. This is enough for about 100 leak pluggings,
giving a foam cost per plugging of -approximately $1.
10. Compatible With Wide Range of Hazardous Chemicals. Large improve-
ment in the chemical compatibility of the plugs was achieved dur-
ing this program by using a membrane on the outside of the appli-
cator to physically separate the curing foam and the hazardous
chemical. It is expected that membranes of different materials
can be used to permit plugging of virtually all of the chemicals
expected to be designated as "hazardous substances" under 40CFR
Part 116 (Ref. 4).
The predicted system capability, including materials compatibil-
ity considerations, is summarized in Table 4, which lists the
300-plus hazardous chemicals given in Ref. 4. An explanation of
symbols used in Table 4 follows: An "x" in Table 4 indicates an
affirmative answer to the question at the top of the column. The
numbers in the "Other Limits on Sealing" column refer to the rel-
ative risk to the leak-plugging operator, with 3 being the high-
est and 1 the lowest risk. Parentheses around an "x" indicate a
marginal evaluation or conditional judgment is also involved.
The evaluation of whether the vapor pressure is too high for leak
plugging was done in relation to the capabilities of the present
leak sealing system. It may be possible to develop the method
further, to enable higher pressure leaks to be sealed.
It can be seen from Table 4 that there are very few hazardous
chemicals that are judged to be not feasible for leak plugging
with the present system. Limitations on the applicability of the
system are seldom caused solely by materials compatibility
59
-------
TABLE 4. PROBABLE LEAK-PLUGGING SUCCESS WITH HAZARDOUS CHEMICALS
LISTED IN 40 CFR PART 116 (REF. 4)
Hazardous Chemical
Common Name
Acetaldehyde
Acetic acid
Acetic anhydride
Acetone cyanohydrin
Acetyl bromide
Acetyl chloride
Acrolein
Acrylonitrile
Adiponitrile
Aldrin
Allyl alcohol
Allyl chloride
Aluminum sulfate
Ammonia
Ammonium compounds :
Ammonium acetate
Ammonium benzoate
Ammonium bicarbonate
Ammonium bisulfite
Ammonium bromide
Ammonium carbamate
Ammonium carbonate
Ammonium chloride
Ammonium citrate, dibasic
Ammonium fluoborate
Ammonium hydroxide
Ammonium hypophosphite
Ammonium iodide
Synonyms
ethanal
ethyl aldehyde
aldehyde
acetic aldehyde
glacial acetic acid
vinegar acid
acetic oxide
acetyl oxide
2-methyllactonitrile
alpha- hydroxyisobutyronitrile
2-propenal
acrylic aldehyde
acrylaldehyde
acraldehyde
cyanoethylene *
Fumigrain
Ventox
propenenitrile
vinyl cyanide
1 , 4-dicyanobutane
Octalene
HHDN
2-propen-l-ol
l-propenol-3
vinyl -carbinol
3-chloropropene
3-chloropropylene
Chloral lylene
alum
acetic acid ammonium salt
acid ammonium carbonate
ammonium hydrogen carbonate
ammonium aminoformate
ammonium muriate
sal ammoniac
salmiac
Amchlor
di ammonium citrate
citric acid diammonium salt
*Numbers refer to relative risk; 3 is highest, 1 is lowest.
Leak-Plugging
System
Applicable
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Other Limits
on Plugging
a Leak
x 2*
x 2*
x 2
60
-------
TABLE 4. (Continued)
Hazardous Chemical
Common Name
Ammonium compounds (continued)
Ammonium nitrate
Ammonium oxalate
Ammonium pentaborate
Ammonium persulfate
Ammonium silicofluoride
Ammonium sulfamate
Ammonium sulfide
Ammonium sulfite
Ammonium tartrate
Ammonium thiocyanate
Ammonium thiosulfate
q
Amyl acetate
Aniline
Antimony compounds:
Antimony pentachloride
Antimony pentafluoride
Antimony potassium tartrate
Antimony tribromide
Antimony trichloride
Antimony trifluoride
Antimony trioxide
Arsenic compounds:
Arsenic acid
Arsenic disulfide
Arsenic pentaoxide
Arsenic trichloride
Arsenic trioxide
Arsenic trisulfide
Synonyms
ammonium decaborate
ammonium peroxydisulfate
ammonium fluosilicate
Animate
AMS
ammonium amidosulfate
tartaric acid ammonium salt
ammonium rhodanide
ammonium sulfocyanate
ammonium sulfocyanide
ammonium hyposulfite.
amylacetic ester
pear oil
banana oil
(isomers are normal-* iso-, secondary-, tertiary -
amyl acetate)
aniline oil
phenylamine
aminobenzene
aminophen
kyanol
tartar emetic
tartrated antimony
tartarized antimony
potassium antimonyltartrate
butter of antimony
antimony fluoride
dianitmony trioxide
flowers of antimony
orthoarsenic acid
arsenic monosulfide
red arsenic sulfide
arsenic acid anhydride
arsenic oxide
arsenic chloride
arsenious chloride
arsenous chloride
butter of arsenic
arsenious acid
arsenious oxide
white arsenic
arsenious sulfide
yellow arsenic sulfide
Leak-Plugging
System
Applicable
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
x
x
Other Limits
on Plugging
a Leak
(x) 2
61
-------
TABLE 4. (Continued)
Hazardous Chemical
Common Name
Arsenic compounds (continued)
Calcium arsenate
Calcium arsenite
Potassium arsenate
Potassium arsenite
Sodium arsenate
Sodium arsenite
Benzene
Benzoic acid
Benzonitrile
Benzoyl chloride
Benzyl chloride
Beryllium compounds
Beryllium chloride
Beryllium fluoride
Beryllium nitrate
Butyl acetate
Butylamine
Butyric acid
Cadmium compounds
Cadmium acetate
Cadmium bromide
Cadmium chloride
Calcium carbide
Calcium hydroxide
Calcium hypochlorite
Calcium oxide
Captan
Carbaryl
Carbon disulfide
Synonyms
tricalcium ortho-arsenate
potassium metaarsenite
disodium arsenate
sodium metaarsenite
cyclohexatriene
benzol
benzenecarboxylic acid
phenylformic acid
dracylic acid
phenyl cyanide
cyanobenzene
benzenecarbonyl chloride
acetic acid normal-butyl ester
acetic acid secondary-butyl ester
acetic acid iso-butyl ester
acetic acid tertiary-butyl ester
(isomers are normal-, secondary, iso-. tertiary-
butyl acetate)
1-; 2-aminobutane
2-amino-2-methyl propane
l-amino-2-methylpropane
(isomers are normal-* secondary-, tertiary-butylamine)
butanoic acid
ethylacetic acid
(isomers are normal-, iso-butyric acid)
carbide
acetylenogen
hydrated lime
slaked lime
calcium hydrate
lime
quicklime
Orthocide-406
SR-406
Vancide-89
Sevin
carbon bisulfide
dithiocarbonic anhydride
Leak-Plugging
System
Applicable
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Other Limits
on Plugging
a Leak
j*
(x) 2
(x) 2
62
-------
TABLE 4. (Continued)
Hazardous Chemical
Common Name
Cadmium compounds (continued)
Chlordane
Chlorine
Chlorobenzene
Chloroform
Chlorosulfonic acid
Chromium compounds:
Ammonium bichromate
Ammonium chromate
Calcium chromate
Chromic acetate
Chromic acid
Chromic sulfate
Chromous chloride
Chromyl chloride
. •
Lithium bichromate
Lithium chromate
Potassium bichromate
Potassium chromate
Sodium bichromate
Sodium chromate
Strontium chromate
Zinc bichromate
Cobalt compounds:
Cobaltous bromide
Cobaltous fluoride
Cobaltous formate
Cobaltous sulfamate
Copper compounds:
Cupric acetate
Cupric acetoarsenite
Cupric chloride
Cupric formate
Cupric glycinate
Cupric lactate
Cupric nitrate
Cupric oxalate
Cupric subacetate
Cupric sulfate
Cupric sulfate, ammoniated
Synonyms
Toxichlor
monochlorobenzene
benzene chloride
trichloromethane
sulfuric chlorohydrin
ammonium dichromate
calcium chrome yellow
gelbin
yellow ultramarine
chromic anhydride
chromium trioxide
chromium dioxychloride
lithium dichromate
potassium dichromate
sodium dichromate
zinc dichromate
cobalt bromide
cobalt fluoride
cobalt formate
cobalt sulfamate
copper acetate
crystallized verdigris
copper acetoarsenite
copper acetate arsenite
Paris green
copper chloride
copper formate
copper glycinate
cupric aminoacetate
copper lactate
copper nitrate
copper oxalate
basic copper acetate
copper sulfate
ammoniated copper sulfate
Leak-Plugging
System
Applicable
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Other Limits
on Plugging
a Leak
x 3
x 3
x 2
63
-------
TABLE 4. (Continued)
Hazardous Chemical
Common Name
Copper compounds (continued!
Cupric tartrate
Cuprous bromide
Coumaphos
Cresol
Cyanide compounds:
Barium cyanide
Calcium cyanide
Hydrogen cyanide
Potassium cyanide
Sodium cyanide
Zinc cyanide
Cyanogen chloride
Cyclohexane
2,4-D (acid)
2,4-D (esters)
Dalapon
DDT
Diazinon
Dicamba
•Dichlobenil
Dichlone
Dichlorvos
Dieldrin
Diethylamine
Dimethylamine
Dinitrobenzene
Dinitrophenol
Diquat
Disulfoton
Diuron
Dodecylbenzenesulfonic acid
Dodecylbenzenesulfonic acid,
calcium salt
Synonyms
copper tartrate
copper bromide
Co-Ral
cresylic acid
hydroxytoluene
(isomers are meta- , ortho-, para-cresol)
hydrocyanic acid
hexahydrobenzene
hexamethylene
hexanaphthene
2,4-dichlorophenoxyacetic acid
2,4-dichlorophenoxyacetic acid esters
Dowpon
Gramevin
Radapon
Unipon
p.p'-DDT
Dipofene
Diazitol
Basudin
Spectracide
2-methoxy-3,6-dichlorobenzoic acid
2,6-dichlorobenzonitrile
2,6-DBN
Phygon
dichloronaphthoquinone
2,2-dichlorovinyl dimethyl phosphate
Vapona
Alvit
dinitrobenzol
Aldifen
(isomers are 2,3-;2,4-;2,5-;2,6-;3,4-;3,5-dinitrophenol)
Aquacide
Dextrone
Reglone
Diquat dibromide
Di-syston
DCMU
DMU
Leak-Plugging
System
Applicable
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Other Limits
on Plugging
a Leak
x 3
x 3
x 1
64
-------
TABLE 4. (Continued)
Hazardous Chemical
Common Name
Cyanide compounds (continued)
Dodecylbenzenesulfonic acid,
isopropanolamine salt
Dodecylbenzenesulfonic acid,
sodium salt
Dodecylbenzenesulfonic acid,
triethanolamine salt
Dursban
Endosulfan
Endrin
Ethion
Ethylbenzene
Ethylenediamine
Ethylenediamine-tetraacetic
acid
Fluorine compounds:
Aluminum fluoride
Ammonium bifluoride
Ammonium fluoride
Hydrofluoric acid
Sodium bifluoride
Sodium fluoride
Stannous fluoride
Formaldehyde
Formic acid
Fumaric acid
Furfural
Guthion
Heptachlor
Hydrochloric acid
Hydroxylamine
Iron compounds:
Ferric ammonium citrate
Ferric ammonium oxalate
Ferric chloride
Ferric fluoride
Ferric nitrate
Synonyms
chlorpyrifos
Thiodan
Mendrin
Compound 269
Nialate
1 , 2-diaminoethane
EDTA
edetic acid
Havidote
(ethylenedinitrilo)-tetraacetic acid
aluminum trifluoride
acid ammonium fluoride
ammonium hydrogen fluoride
neutral ammonium fluoride
fluohydric acid
villiaumite
methyl aldehyde
methanal
formalin
methanoic acid
trans-butenedioic acid
trans-l,2-ethylenedicarboxylic acid
boletic acid
allomaleic acid
2-furaldehyde
pyromucic aldehyde
Gusathion
azinphos-methyl
Velsicol-104
Drinox
Heptagran
hydrogen chloride
muriatic acid
oxammonium
ammonium ferric citrate
ammonium ferric oxalate
flores martis
iron trichloride
iron nitrate
Leak-Plugging
System
Applicable
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Other Limits
on Plugging
a Leak
x 3
(x)2
(x)2
x 2
65
-------
TABLE 4. (Continued)
Hazardous Chemical
Common Name
Iron compounds (continued)
Ferric sulfate
Ferrous ammonium sulfate
Ferrous chloride
Ferrous sulfate
Isoprene
Kel thane
Lead compounds:
Lead acetate
Lead arsenate
Lead chloride
Lead fluoborate
Lead fluoride
Lead iodide
Lead nitrate
Lead stearate
Lead sulfate
Lead sulfide
Lead tetraacetate
Lead thiocyanate
Lead thiosulfate
Lead tungstate
Lindane
Malathion
Maleic acid
Maleic anhydride
Mercury compounds:
Mercuric acetate
Mercuric cyanide
Mercuric nitrate
Mercuric sulfate
Synonyms
ferric persulfate
ferric sesquisulfate
ferric tersulfate
Mohr's salt
iron ammonium sulfate
iron chloride
iron dichloride
iron protochloride
green vitriol
iron vitriol
iron sulfate
iron protosulfate
2-methyl-l , 3-butadiene
di (p-chlorophenyl) -trichloromethylcarbinol
DTMC
dicofol
sugar of lead
lead difluoride
plumbous fluoride
stearic acid lead salt
galena
lead sulfocyanate
gamma -BHC
gamma-benzene hexachloride
phosphothion
cis-butenedioic acid
cis-l,2-ethylenedicarboxylic acid
toxilic acid
2,5-furandione
cis-butenedioic anhydride
toxilic anhydride
mercury acetate
mercury cyanide
mercury nitrate
mercury pernitrate
mercury sulfate
mercury persulfate
mercury bisulfate
Leak-Plugging
System
Applicable
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Other Limits
on Plugging
a Leak
66
-------
TABLE 4. (Continued)
Hazardous Chemical
Common Name
Mercury compounds (continued)
Mercuric thiocyanate
Mercurous nitrate
Methoxychlor
Methyl mercaptan
Methyl methacrylate
Methyl parathion
Mevinphos
Monoethylamine
Monoraethylamine
Naled
Naphthalene
Naphthenic acid
Nickel compounds
Nickel ammonium sulfate
Nickel chloride
Nickel formate
Nickel hydroxide
Nickel nitrate
Nickel sulfate
Nitric acid
Nitrobenzene
Nitrogen dioxide
Nitrophenol
Paraformaldehyde
Parathion
Pentachlorophenol
Phenol
Synonyms
mercury thiocyanate
mercuric sulfocyanate
mercuric sulfocyanide
mercury protonitrate
DMDT
methoxy-DDT
methanethiol
mercaptomethane
methyl sulfhydrate
thiomethyl alcohol
methacyrlic acid methyl ester
methyl -2-methyl-2-propenoate
Nitrox-80
Phosdrin
ethylamine
aminoethane
methylamine
aminomethane
Dibrom
white tar
tar camphor
naphthalin
cyclohexanecarboxylic acid
hexahydrobenzoic acid
ammonium nickel sulfate
nickelous chloride
nickelous hydroxide
nickelous sulfate
aqua fortis
nitrobenzol
oil of mirbane
nitrogen tetraoxide
mononitrophenol
(isomers are meta-, ortho-, para-nitrophenol)
Paraform
Formagene
Triformol
polymerized formaldehyde
polyoxymethylene
DNTP
Niran
PCP
Penta
carbolic acid
phenyl hydroxide
hydroxybenzene
oxybenzene
Leak-Plugging
System
Applicable
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
—
Other Limits
on Plugging
a Leak
x 1
x 1
x 2
x 3
67
-------
TABLE 4. (Continued)
Hazardous Chemical
Common Name
Phosgene
Phosphoric acid
Phosphorus
Phosphorus oxychloride
Phosphorus pentasulfide
Phosphorus trichloride
Polychlorinated biphenyls
Potassium hydroxide
Potassium permanganate
Propionic acid
Propionic anhydride
Propyl alcohol
Pyrethrins
Quinoline
Resorcinol
Selenium compounds:
Selenium oxide
Sodium selenite
Sodium
Sodium bisulfite
Sodium hydrosulfide
Sodium hydroxide
Sodium hypochlorite
Sodium methylate
Synonyms
diphosgene
carbonyl chloride
chloroformyl chloride
orthophosphoric acid
black phosphorus
red phosphorus
white phosphorus
yellow phosphorus
phosphoryl chloride
phosphorus chloride
phosphoric sulfide
thiophosphoric anhydride
phosphorus persulfide
phosphorous chloride
PCB
Aroqlor
Polychlorinated diphenyls
potassium hydrate
caustic potash
potassa
chameleon mineral
propanoic acid
methylacetic acid
ethylformic acid
propanoic anhydride
methylacetic anhydride
ethyl carbinol
propylic alcohol
propanol
(isomers are normal-, iso-propyl alcohol)
Pyrethrin I
Pyrethrin II
1-benzazine
benzo [b] pyridine
leucoline
chinoleine
leucol
resorcin
1,3-benzenediol
meta-dihydroxybenzene
selenium dioxide
natrium
sodium acid sulfite
sodium hydrogen sulfite
sodium sulfhydrate
caustic soda
soda lye
sodium hydrate
bleach
sodium methoxide
Leak-Plugging
System
Applicable
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Other Limits
on Plugging
a Leak
x 3
(x)2
x 3
x 3
(x)2
x 2
(x)2
68
-------
TABLE 4. (Concluded)
Hazardous Chemical
Common Name
Sodium nitrite
Sodium phosphate, dibasic
Sodium phosphate, monobasic
Sodium phosphate, tribasic
Sodium sulfide
Strychnine
Styrene
Sulfuric acid
Sulfur monochloride
2,4,5-T (acid)
2,4,5-T (esters)
TDE
T«traethyl .lead
Tetraethyl pyrophosphate
Toluene
Toxaphene
Trichlorfon
Trichlorophenol
Triethylamine
Trimethylamine
Uranium compounds:
Uranium peroxide
Uranyl acetate
Uranyl nitrate
Uranyl sulfate
Vanadium compounds:
Vanadium pentoxide
Vanadyl sulfate
Vinyl acetate
Xylene
Xylenol
Zectran
Synonyms
vinylbenzene
phenylethylene
styrol
styrolene
cinnamene
cinnamol
oil of vitriol
oleum
sulfur chloride
2,4.5-trichlorophenoxyacetic acid
2,4,5-trichlorophenoxyacetic esters
ODD
lead tetraethyl
TEL
TEPP
toluol
methylbenzene
phenylmethane
Methacide
camphechlor
Dipterex
Dylox
Collunosol
Dowicide 2 or 2S
Omal
Phenachlor
TMA
vanadic anhydride
vanadic acid anhydride
vanadic sulfate
vanadium sulfate
acetic acid ethylene ether
dimethylbenzene
xylol
(isomers are meta-, ortho-, para-xylene)
dimethylphenol
hydroxydimethyl benzene
mexacarbate
Leak-Plugging
System
Applicable
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Other Limits
on Plugging
a Leak
(x)2
x 2
69
-------
TABLE 4. (Continued)
Hazardous Chemical
Common Name
Zinc compounds:
Zinc acetate
Zinc ammonium chloride
Zinc borate
Zinc bromide
Zinc carbonate
Zinc chloride
Zinc fluoride
Zinc formate
Zinc hydrosulfite
Zinc nitrate
Zinc phenolsulfonate
Zinc phosphide
Zinc potassium chromate
Zinc silicofluoride
Zinc sulfate
Zinc sulfate, monohydrate
Zirconium compounds :
Zirconium acetate
Zirconium potassium fluoride
Zirconium nitrate
Zirconium oxychloride
Zirconium sulfate
Zirconium tetrachloride
Synonyms
'
butter of zinc
zinc sulfocarbolate
zinc yellow
citron yellow
buttercup yellow
zinc chrome
zinc fluosilicate
white vitriol
zinc vitriol
white copperas
zirconyl chloride
zirconium chloride, basic
disulfatozirconic acid
Leak-Plugging
System
Applicable
X
X
X
X
X
X
X
X
X
X
X
X
X
x
x
x
X
X
X
x
Other Limits
on Plugging
a Leak
002
NOTE 1:
NOTE 2:
When both columns are marked, the plugging capability depends on such factors as the weather, humidity,
and spill location (e.g., underwater versus air).
Some so-called synomyns actually refer to different physical forms of the compound.
affect the "plugability" rating.
If so, they may
70
-------
limitations, i.e., where materials compatibility is a problem,
the vapor pressure is also excessively high, and/or the risk to
operator personnel is high.
A neoprene membrane fulfills the compatibility requirement for
the great majority of the materials in the list of 300-plus haz-
ardous chemicals (Table 4). Buna-N and polyimid polyester mater-
ials cover most of those remaining. Should a material be found
that is not compatible with the three above, silicone rubber
should be considered; also a possibility exists that a membrane
made of polytetrafluoroethylene, PTFE (Teflon), can be used.
This would result in a combination of membrane materials comp-
atible with essentially all the chemicals in the list. Leak-
plugging tests have been made with neoprene and polyimid poly-
ester membranes; expected Buna-NL applicability is based on
published compatibility information obtained from glove manufac-
turers and chemical laboratory wear manufacturers.
It is also possible to use two membranes, one surrounding the
other, to achieve the desired combination of chemical and phys-
ical properties for difficult chemicals. This was done to seal
an ethylene trichloride leak where an ordinary latex membrane
(which is attacked by ethylene trichloride) was used inside a
relatively large, thin, polyimi'd bag. The outside bag was thin,
strong, and roomy while the inside bag was extremely elastic and
served also to compress the sponge in the applicator tip, making
insertion easier. The outside bag was folded and lightly tacked
in place with a fastener strong enough to keep it in place during
insertion, but weak enough so that it easily loosened during ex-
pansion of the foam inside the applicator.
11. Ability to Completely Plug Leaks. The completeness of the leak
plugging depends primarily on the irregularity of the edges of
the hole to be plugged. With fairly regular, smooth-edged holes,
it is not uncommon to produce a completely tight seal. Even with
very irregular holes, the flow will be reduced to a few percent
of the original leak.
12. Safe and Easy to Use by Untrained Personnel. This subject is
discussed in the next part of Section VI, "Implementation Plan."
In summary, the leak-plugging system does not require much oper-
ator skill. It could be used by someone completely unfamiliar
with the system. However, the speed and, to some extent, the
success of a leak-plugging operation will be improved by provid-
ing a potential operator with a brief checkout and test use of
the system in advance of an emergency situation.
The safety issues in the use of the system arise from the poten-
tial hazards of the leaking chemical itself. The applicator
poles in the delivered prototypes are about 2.5 meters (7.5 feet)
long. This moves the operator partly back away from the splash
zone. However, protective clothing should be worn by the oper-
ator. Further, during planning for deployment careful attention
U.S EPA Headquarters Library
71 Mail coo* 3404T
•i 200 Pennsylvania Avenue NW
uvssh;i.gton, DC 20460
202-566-0556
-------
should be given to identify hazardous chemicals which are too
dangerous for practical plugging (except by highly trained and
well-equipped emergency personnel). Table 4 represents a pre-
liminary estimate of those chemicals which could be handled by
trained personnel; leaks of some of these chemicals should not be
plugged by unskilled personnel.
13. Flexibility in Hole Size, Shape, and Location. The present leak-
plugging system permits successful plugging with considerable
flexibility in hole size, shape, and location. Successful tests
have been made with holes from 2.5 cm (1 inch) to 10 cm (4 inches)
across, cracks 1.3 cm (1/2 inch) by 15 cm (6 inches), and with
various shapes and degrees of jaggedness (including ragged holes
cut in the plane of the tank wall and also punctured holes with
rough sections in three dimensions). The applicator tip design
(with an outer membrane) does impose some constraints on the
ability of the tip to expand into very small crevices and irregu-
larities at the edges of a hole. However, the expansion both in-
side and outside the tank wall tends to block and plug even con-
siderable irregularities.
It is expected that the present leak-plugging concept can be used
over an even wider range of hole sizes than tested to date. With
a variety of applicator tip sizes and shapes, together with a
variable-volume foam supply device, it should be possible to plug
holes from about 1 cm (1/2 inch) to 30 cm (12 inches) across, and
cracks as thin as 0.3 cm (1/8 inch). The capabilities in hole
size are related to liquid heads and temperature. This is fur-
ther discussed in the next subsection.
The present method permits insertion of the applicator at almost
any angle and therefore provides wide flexibility in hole loca-
tion. Any hole into which an operator can insert the end of a
long stick can usually be plugged using the present method. The
angle between the axis of the applicator and the surface of the
tank at the hole need not be 90 degrees; it can be as low as 20
degrees and still obtain a satisfactory plug.
Successful leak-plugging tests were made also with leaks sub-
merged under water. There is no additional difficulty in plug-
ging leaks under water, as compared with in air, except for
operator access and visibility.
14. Usable With Liquid Heads as High as Those Encountered in Tank
Cars. The prototype system has been used successfully to plug
leaks against liquid heads as high as those encountered in tank
cars. Any limitations on allowable liquid head result primarily
from human strength plus logistics considerations, not from in-
herent limitations in the leak-plugging system. The practical
range of liquid heads against which leaks can be plugged depends
on several factors, including leak size, elevation of the leak
relative to the tank, tank volume and proportions, orientation
of the tank, and fluid density. This is further discussed below.
72
-------
The volume of tank trucks and trailers for highway use normally
ranges from about 10,000 to 32,000 liters (2600 to 8450 gallons).
The tanks are usually cylindrical or have an elliptical cross-
section, and are typically about 1.7 to 3 meters (5.6 to 10 feet)
in "diameter" by 4.6 to 12 meters (15 to 40 feet) long. Railroad
tanks and tank cars typically have volumes from about 8400 to
114,000 liters (2200 to 30,000 gallons). Inland barges are
either 10.6 or 16 meters (35 or 52.5 feet) wide, are either 59.4
or 76 meters (195 or 250 feet) long, have depths in the range
2.7 to 4.3 meters (9 to 14 feet), and have capacities up to 2500
metric tons (about 2,500,000 liters or 660,000 gallons of a fluid
with specific gravity of one).
Human strength is one of the major considerations in defining the
liquid heads against which leaks can be plugged. The purpose of
this program was to develop a prototype system for portable use
by one man. This means that a single operator must be able to
exert a force sufficient to hold a plug in place against the hy-
draulic pressure of the leak for perhaps 1/2 minute. The type of
leak-plugging concept used in the prototype could be further de-
veloped for multi-man or mechanical operation, thus going beyond
the strength limitations of a single man.
The fluid head exerted on a leak depends on the tank size, shape,
and relative elevation of the hole. Figure 27 gives parametric
values of fluid head for a range of tank sizes, orientations, and
hole locations. For simplicity, cylindrical tanks with flat ends
are used in this generalized representation. The tank shape is
expressed as a geometric factor (e) equal to the tank length
divided by the equivalent diameter. (Typical values of e for
highway and railway tankers are 3 to 7.) Curves 3 through 6 of
Fig. 27 represent what is expected to be more common situations
encountered in tanker accidents. Curves 1 and 2 (Fig. 27) rep-
resent rather unusual cases, which would result in particularly
high liquid heads (e.g., curve 1 assumes the tanker is standing
on its end, with the tank completely full of liquid and the hole
at the very bottom of the tank).
One of the very interesting conclusions that can be drawn from
Fig. 27 is that most of the leak-plugging applications should
involve fairly moderate liquid heads, e.g., less than about 2
meters (7 feet) for highway tank trucks, and less than about 3
meters (10 feet) for railway tank cars. The prototype leak-
plugging system has been used successfully to plug 10-cm (4-
inches) holes against a fluid head of 3.7 meters (12 feet) of
water.
The force that a single operator must exert to hold a plug
against the leaking fluid depends on the fluid head, the size of
the hole, and the fluid density. Figure 28 shows parametrically
the tradeoffs between these three variables for a constant op-
erator force of 233 Newtons (50 Ibf), which is estimated to be
the maximum usable force that a single man can exert in a hori-
zontal direction. This usable force was corroborated during this
73
-------
CO
CC
Q
<
12
11
10
9
8
7
6
5
4
3
2
I
OL.
,- 40
Q
=; 30
u- 20
•t
Q
— ^
LU
:c
Q
13
I- r1 10
40
1: VERTICAL, e=4, LEAK AT BOTTOM
2: 30-DEGREE LIST, e=4, LEAK AT BOTTOM
AND VERTICAL, e=4, LEAK AT MIDDLE
3: HORIZONTAL, e=4, LEAK AT BOTTOM AND
30-DEGREE LIST, e=4, LEAK AT MIDDLE
4: HORIZONTAL, e=6, LEAK AT BOTTOM
5: HORIZONTAL, e=4, LEAK AT Ml DOLE
6: HORIZONTAL, e=6, LEAK AT MIDDLE
i I i I I
100
400
1000
kOQO 10,000
kO,QQO 100,000
1 I Mill
TANK VOLUME, GALLONS
I I I I I I I I I
I I I I I I I I
400
1000
4000 10,000 40,000 100,000
TANK VOLUME, LITERS
400,000
Figure 27. Maximum Fluid Head in Various Containers
-------
•-J
Cn
o
CO
LU
3:
12
11
10
9
8
7
6
30
20
_ <
3
2
1
0
10
AREA OF
PRACTICAL
APPLICATIONS
SPECIFIC GRAVITY =0.7
I I
AREA WHERE HYDRAULIC PRESSURE
IS TOO GREAT FOR LEAK TO BE
STOPPED BY ONE MAN
k 6 8
CHARACTERISTIC DIAMETER OF LEAK, INCHES
I I I
10 15 20
CHARACTERISTIC DIAMETER OF LEAK, CM
10
25
12
30
Figure 28. Envelope of Practical Fluid Head and Leak Sizes for One-Man Operation
-------
program. It was found that with a fluid head of 3.7 meters (12
feet) of water, an operator could plug an 8-cm (3-inch) hole
readily, a 9-cm (3-1/2-inch) hole with moderate difficulty, and
a 10-cm (4-inch) hole only with maximum exertion. The leak
equivalent diameter for a head of 3.7 meters (12 feet) and a
specific gravity of 1.0 is about 9-cm (3.5 inches) -from Fig. 28.
Figure 28 also can be used to evaluate the approximate relation-
ship between leak size and head. For example (with a 0.7 spe-
cific gravity fluid), it would be roughly as easy to plug a 5.6-
cm (2.2-inch) hole with 12 meters (13 feet) of head, or a 15-cm
(6-inch) hole with 1.8 meters (6 feet) of head.
The second major consideration in defining the usable range of
the leak-plugging system is the time of response. Obviously, a
very large hole in a small container will result in a complete
loss of the contents before corrective action can be taken.
Therefore, there is an upper limit on hole size (as a function
of container size, liquid head, and response time) which it is
practical to consider. Efflux times can be calculated for any
given container geometry and orientation, hole size and location,
and type of liquid. An analysis was made, using the following
assumptions:
a. Leak sizes may be specified by a single characteristic
diameter.
b. Containers have a cross-sectional area that does not vary with
liquid height and is specified by a characteristic diameter.
c. Leaks occur at the bottom of the vessel.
d. The effective container height divided by the characteristic
diameter is a known value, (e), which is generally less than
the actual container height divided by the actual diameter.
Figure 29 (taken from Ref. 3) shows results (curves Al and A2)
for the adverse case of a cylindrical container standing on end
with the leak at the bottom of the container. Even under these
unusual conditions, it would be practical to seal large leaks,
e.g., 8 to 13 cm (3 to 5 inches), in tank trucks and tank cars.
For the more usual types of leaks (tanks not upended vertically
and holes not at the very bottom of the tank), the time for re-
sponse and/or practical leak size to plug before substantial
chemical loss occurred would be much higher.
15. Wide Temperature Tolerance. The supplier of the baseline foam
components (Olin Corporation) recommends rather restrictive tem-
perature limits for the foam components and Olin foam guns.
Selected recommendations from this supplier are cited below:
a. Material cylinders should never be stored at temperatures be-
low 21 C (70 F) or above 32 C (90 F).
76
-------
>
o
300,000
150,000
75,000
30,000
1
0
J
•V
J 15,000
7500
100,000
80,000
60,000
_ 40,000
o
o
3000
1500
750
300
150
AREA WHERE HYDRAULIC
PRESSURE IS TOO GREAT
FOR LEAK TO BE STOPPED
BY ONE MAN
CURVE B2
e - 0.5)
CURVE Bl
(e = 1.5)
10,000
8000
6000
AREA OF PRACTICAL
APPLICATIONS
AREA WHERE LEAKAGE
RATE IS TOO RAPID
TO ALLOW CORRECTIVE
ACTION BEFORE CONTENTS
OF CONTAINER ARE LOST
1
CHARACTERISTIC DIAMETER OF LEAK, INCHES
I I I I I I I I I I
23456789 10
CHARACTERISTIC DIAMETER OF LEAK, CM
11 12
Figure 29. Envelope of Practical Applications for Sealing
Leaks in Nonsubmerged Containers
77
-------
b. For optimum operation, material temperatures in the cylinders
should be above 24 C (75 F) and below 32 C (90 F).
c. These temperature ranges are critical as they can affect the
ratio and reactivity of the foam systems.
d. Excessive direct heat should never be applied to any cylinder.
In order to bring the chemicals contained in the cylinders up
to operating temperatures, they should be placed in a warm
environmental room, or box, for a period sufficient to allow
a gradual warming of the chemicals.
Considerable effort was made during this program to extend the
usable temperature range beyond the usual commercial practice.
It was found that commercially available urethane foam delivery
systems did not maintain the correct component mixture ratio at
low temperatures because the flow control was maintained through
pressure drop and the two components have large differences in
temperature effect on viscosity. Development efforts during this
program have eliminated this problem through introduction of an
inert mixing gas. This development also permits elimination of
a static mixer tube, thereby avoiding the high-pressure drop that
is experienced in a static mixer when flowing very cold urethane
foam components.
As a result of the development work, successful tests were made
when the temperature of the foam, delivery equipment, and leaking
fluid was as low as 7 C (44 F) and as high as 38 C (100 F). In
addition, a successful foam expulsion test was made with the foam
and hardware at about 18 C (65 F), then chilled in a 0 C (32 F)
atmosphere for 3 minutes before firing. The latter test was made
to approximate the operational situation in which the leak-plug-
ging equipment was removed from a storage location at moderate
temperatures and brought outside just prior to its use at winter
temperatures. Additional tests are needed to more completely
evaluate the temperature capabilities of the prototype system.
The following approximate guide is suggested, pending further
evaluation: the prototype system with the baseline 01in No.
202-C1 urethane foam is usable when the foam and hardware have
been stored between about 10 and 38 C (50 and 100 F). The sys-
tem also can be used to plug leaks at much colder temperatures,
down to at least 0 C (32 F), provided the system is not exposed
to the colder temperatures for more than about 3 minutes before
use.
IMPLEMENTATION PLAN
The prototype leak-plugging system described in this report has been de-
veloped to the point that it is now realistic to project practical field
use of such a system. There are at least two major facets to consider in
planning the future operational use of a leak-plugging system: motiva-
tional forces (i.e., what will motivate production development, manufacture,
78
-------
and purchase of the devices) and technical dimensions (such as exactly
which device to use, where they will be deployed, who will use them, etc.).
These major facets are discussed in this section.
Motivational Forces
Wide-scale operational use of such a leak-plugging system (or any other
system that mitigates the potential effects of hazardous materials spills)
will occur only if there is a clear need or requirement for transportation
companies and/or emergency crews to purchase and deploy such equipment. A
second requisite, before wide-scale operational use of such a system can
be made, is for a manufacturing company to complete a production develop-
ment project to bring the present prototype to a version suitable for
economical mass production. This production development will occur only
if there is a good potential market for the product.
It is expected that legislation or regulations will be required to moti-
vate implementation. These may be,new requirements or they may be de-
veloped within the framework of existing regulations (e.g., if the penal-
ties for chemical spills become great enough to motivate purchases of
devices to mitigate the effects of potential spills).
Technical Dimensions
Large tanks containing hazardous chemicals can be divided into categories,
e.g., (1) highway trucks and trailers, (2) railroad cars, (3) barges and
other watercraft, (4) stationary storage tanks and loading facilities, and
(5) pipelines.
In each of the first four categories, a leak-plugging system could be car-
ried on the transportation vehicle or at the loading site. The equipment
then would be readily available at the earliest possible time to plug a
leak. In some accidents, the equipment and/or personnel at the site of
the leak may be incapacitated by the same accident that caused the leak,
e.g., a case of a damaged tank truck that suffered an accident in which
the driver was injured or the leak-plugging equipment was damaged. From
this point of view, the best (or a backup) storage location for leak-
plugging equipment would be a centrally located emergency center such as
a fire department or equivalent which has trained personnel who can re-
spond immediately to a call for assistance. The disadvantage to a more
centrally located deployment is the time delay involved before the leak
can be plugged.
A combination of on-site and centeral deployment may be the best overall
plan. The following are possible combinations:
1. Simple passive equipment on each tank truck
2. The basic leak-plugging system on some tank trucks (with higher
hazard potential), on trains carrying hazardous chemicals, at
hazardous chemical handling facilities, and at major fire depart-
ment/emergency crew facilities
79
-------
3. Additional (e.g., larger, varied) leak-plugging plus other spill
response devices deployed at selected fire department/emergency
crew locations, with EPA and Coast Guard response teams, and
(eventually) with commercial spill response companies
For example, the passive solid rubber cone plugs constructed of silicone
rubber (described in Section V) and mounted on the end of a collapsible
pole could be used effectively to partially seal holes in tanks by simply
pushing them into the holes. Such devices are very inexpensive and easy
to use. A suit of protective clothing also would be provided. These de-
vices would be used by the vehicle operator to administer "first aid"
until an emergency crew could arrive at the scene of the accident with a
basic leak-plugging system (similar to the prototypes described in Section
VI).
Additional work is needed to prepare the way for deployment and wide-scale
operational use of the EPA leak-plugging system, through establishing the
basis for two essential subsequent actions: (1) legislation or regulations
that establish a realistic need for the type of environmental protection
afforded by a leak-plugging device, and (2) production development by in-
terested manufacturing companies.
An evaluation should be made of data already collected on past hazardous
materials spills to estimate the potential benefits that could have been
realized if various leak-plugging systems had been available. Three stages
of deployment (with different degrees of proximity to an accident site)
should be considered: (1) system is on the transportation vehicle or
chemical handling site, (2) system is available at the nearest city fire
department, and (3) system is available at a central location within the
EPA region in which the accident occurred. Estimates then should be made
of the costs to deploy leak-plugging equipment to various degrees (includ-
ing the three levels of deployment mentioned above). The potential im-
pacts of these costs should be estimated, including such questions as who
would pay for the emergency repair equipment, the degree to which these
would impact shipping and chemical costs, etc.
Detailed discussions should be held with individuals who can accurately
represent the positions and attitudes of various organizations that would
be affected by and involved in the use of leak-plugging devices. These
organizations might include EPA National Contingency Plan personnel,
Coast Guard and other DOT personnel, municipal fire departments, trucking
companies, railroad companies, barge companies, unions, chemical companies,
and various trade associations. The purpose of these discussions would be
to obtain information and options that will permit further definition of
the detailed requirements to be imposed on use of the system, and an
assessment of the degree of cooperation or resistance to deployment and
use of leak-plugging devices either on transportation elements or at emer-
gency crew locations. It is important to determine practical expectations
for both deployment locations and type of personnel who will use the
devices.
80
-------
After completion of the portion of this task dealing with assessing user
acceptance, and incorporation of any necessary changes to promote operator
safety and confidence, there should be a modest effort to field test and
demonstrate one or more leak-plugging systems devices with personnel from
transportation and emergency organizations.
Based on the estimates of potential benefits and costs, personnel require-
ments, and the field testing (with various combinations of leak-plugging
equipment deployed in any or all of three levels), trade-off studies
should be made to determine when and in what way operational use of the
EPA leak-plugging equipment should be made. Consideration should be given
to various requirements and constraints (e.g., technical, economic, legal,
human, and logistic).
81
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SECTION VII
REFERENCES
1. Wilder, Ira, and J. Lafornara, Control of Hazardous Materials Spills
in the Water Environment: An Overview, presented before the Division
Water, Air and Waste Chemistry, American Chemical Society, Washington,
D.C., September 1971.
2. Mitchell, R. C., M. Kirsch, C. L. Hamermesh, and J. E. Sinor, "Methods
for Plugging Leaking Chemical Containers," Proceedings of the 1972
National Conference on Control of Hazardous Material Spills, Houston,
Texas, 21-23 March 1972.
3. Mitchell, R. C., C. L. Hamermesh, and J. V. Lecce, Feasibility of
Plastic Foam Plugs for Sealing Leaking Chemical Containers, Report
EPA-R2-73-251, Rocketdyne Division, Rockwell International, Canoga
Park, California, for the U.S. Environmental Protection Agency,
Contract No. 68-01-0106, May 1973.
4. "Environmental Protection Agency (40 CFR Part 116) Designation of
Hazardous Substances, Notice of Proposed Rule Making," Federal Register,
Vol. 40, No. 250, 30 December 1975.
5. R-9604, Plugging Large Leaks in Ruptured Containers, 16 mm color/
sound film, Rocketdyne Division, Rockwell International, Canoga Park,
California, February 1975.
82
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SECTION VIII
PUBLICATIONS AND PATENTS
Mitchell, R. C., J. J. Vrolyk, R. W. Melvold, and I. Wilder, "System for
Plugging Leaks From Ruptured Containers," Proceedings of the 1974 National
Conference on Control of Hazardous Material Spills, San Francisco, Calif-
ornia, 25-28 August, 1974.
Mitchell, R. C., J. J. Vrolyk, R. W. Melvold, and I. Wilder, "Prototype
System for Plugging Leaks in Ruptured Containers," Proceedings of the 1976
National Conference on Control of Hazardous Material Spills, New Orleans,
Louisiana, 25-28 April 1976.
83
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SECTION IX
APPENDICES
A. Leak-Plugging System Design Drawings and Parts List
B. Refilling the Foam Delivery System
84
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APPENDIX A
LEAK-PLUGGING SYSTEM DESIGN
DRAWINGS AND PARTS LIST
Reduced sections of the master design drawing* showing details of the leak-
plugging system appears in Fig.A-1 through A-6. followed by the parts list
in Table A-l. The part numbers in the parts list also appear in small
circles next to the corresponding components in the drawings. The parts
list gives the item function (or name), the supplier, supplier's part num-
ber, size and type connection or interface, the operating pressure, and
design and procurement comments.
The numbers appearing in parentheses on the design drawings are the inch
dimensions converted to centimeters. Because suppliers do not identify
components in metric terms, metric conversion was not rendered on the parts
list.
The delivered prototype systems discussed in this report involve two dif-
ferent delivery system sizes. The size refers to the tandem cylinder
size: The large cylinder has a total displacement (both compartments) of
614.0 cc (34.47 in.3) and the small one has 345.5 cc (21.08 in.3). Also
discussed are two different means of actuation--penumatic and mechanical.
Actually constructed and appearing in the various photographs are: (1)
the large tandem cylinder with the pneumatic actuation, and (2) the small
tandem cylinder with mechanical actuation. The other two possible combin-
ations can be built, if desired.
The drawings show a combination of the pneumatic actuation with the small
tandem cylinder. Only small changes in tubing length are required to con-
vert from a small to a large tandem cylinder; these changes are called out
in the notes at the end of the parts list.
The parts list refers to the parts of the pneumatically actuated system
with the large tandem cylinder as built. This is a baseline to which all
other changes (to obtain other combinations) refer. To change from pneu-
matic to mechanical actuation, the instructions in Note 8 should be fol-
lowed. To change from a large to a small tandem cylinder, the instructions
Notes 2 and 5 should be followed.
*Completed, full-size drawings are available at the U.S. Environmental
Protection Agency, Industrial Environmental Research Laboratory,
Edison, New Jersey, 08817.
85
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APPLICATOR
TIP
a.
HANDLE
VENT
ACTUATION
CONTROL
PIPING SCHEMATIC
Circled numbers refer to component description in the Parts List
Figure A-l. Schematic Diagram of Pneumatically Operated Prototype
Leak Plugging System
86
-------
00
DELIVERY SYSTEM ASSEMBLY
Figure A-2. Plan View of Pneumatically Actuated Prototype Delivery System (scale is
approximately 1/2 actual)
-------
C?28.£)
H/IMDLE:
Figure A-3. End View of Pneumatically Actuated Prototype Delivery
System (scale is approximately 1/2 actual) and Detail
Drawing of Applicator Handle
88
-------
OO
to
Figure A-4. Applicator Assembly (scale is approximately 1/3 actual) and Applicator Tip Detail
Drawing
-------
re
rrff-A ts tfftsrrcA*. TV
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ro r#e
/a
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o
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r "^* of.vs) \ * r *^
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APPL/C/ITOK TUBE. - TYPE-/
—
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(32)
Figure A-5. Applicator Tube Detail Drawing (scale is approximately 1/2 actual)
-------
APPLICATOR.
M/X//VG ASSEMBLY
Figure A-6. Applicator Mixing Assembly Drawing (scale is
approximately 1/2 actual)
91
-------
TABLE A-l. PROTOTYPE PARTS LIST
NAME: URGE DELIVERY SYSTEM
Item
,
2
3
4
5
6
7
8
g
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
27
28
29
30
31
32
33
34
35
36
37
38
39
Item Function
InfUtor With Jerk Tab
Cylinder, Carbon Dioxide
Pressure Regulator
Pressure Regulator
3-Kay Kail Valve
Valve and Actuator
Valve and Actuator
Check/Needle-Valve
Special Tee
Special Tee
Pipe Nipple
Pipe Nipple
Pipe Nipple
Adapter Fitting
Adapter Fitting
Adapter Fitting
Adapter Fitting
Tee
Elbow
Bushing
Adapter Fitting
Adapter Fitting
Nipple
Bushing
Bushing
Bushing
Bushing
Male Run Tee
Hale Run Tee
Pressure Relief Valve
Pressure Relief Valve
Quick Disconnect
Valve Coupler
Quick Disconnect
Valve Coupler
Quick Disconnect
Valve Coupler
Quick Disconnect
Valve Coupler
Quick Disconnect
Valve Coupler
Manufacturer and Part Number
Aeromarine Manufacturing, Del Ray Beach, Florida
A-145 (PN-316S-2)
Sparklett Devices, Inc., St. Louis, Missouri
No. 240 MIL C-25369B Type I
Veriflo Corp., 41300483, IM02-B-250 G
C. A. Norgen, Teglen Engineering, El Monte,
California, R37-200-N70A
Whitey Co. , Oakland, California, B-42XF2
Nhitey Co. , Oakland, California, B-9254
Whitey Co., Oakland, California, B-93S4
DELTROL, Bellwoqd, Illinois, CPN-10-B, Size 10
Airdrome Parts Co., Long Beach, California
AN-825 S.S.
Airdrome Parts Co., Long Beach, California
AN-825 S.S.
Airdrome Parts Co., Long Beach, California
AN-911-1 S.S.
Airdrome Parts Co., Long Beach, California
AN-911-1 S.S.
Airdrome Parts Co., Long Beach, California
AN-911-1 S.S.
Swagelok;Ventura Valve and Fitting Co.,
Newberry Park, California, NY-400-1-4 (Nylon)
Swagelok: Ventura Valve and Fitting Co.,
Newberry Park, California, NY-400-1-2 (Nylon)
Swagelok: Ventura Valve and Fitting Co.,
Newberry Park, California, NY-400-1-2 (Nylon)
Swagelok: Ventura Valve and Fitting Co.,
Newberry Park. California, NY-400-1-2 (Nylon)
Airdrome Parts Co., Long Beach, California
AN-917-1 S.S.
Airdrome Parts Co., Long Beach, California
AN-914-2 S.S.
Airdrome Parts Co. , Long Beach, California
AN-912-1 S.S.
Airdrome Parts Co.. Long Beach, California
AN-B16-4-4 S.S.
Airdrome Parts Co.. Long Beach, California
AN-816-4-4 S.S.
Airdrome Parts Co., Long Beach, California
AN-911-2 S.S.
Airdrome Parts Co., Long Beach, California
AN-912-2 S.S.
Airdrome Parts Co. , Long Beach, California
AN-912-2 S.S.
Airdrome Parts Co., Long Beach, California
AN-912-1
Airdrome Parts Co. , Long Beach, California
AN-912-1
Cajon: Ventura Valve Fitting Co., Newbury Park,
California, Brass B-4-ST
Cajon: Ventura Valve Fitting Co., Newbury Park,
California, Brass B-4-ST
Hoke, Inc., Cresskill, New Jersey, 6514MB
Adjustable with Teflon seat
Hoke, Inc., Cresskill, New Jersey, 6514L4B
Adjustable with Teflon seat
Haskell engineering Co., Burbank, California
VHC 4-4 HMV
Haskell Engineering Co, , Burbank, California
VHC 4-4 MMV
Haskell Engineering Co., Burbank, California
VHC 4-4 MMV
Haskell Engineering Co., Burbank. California
VHC 4-4 MMV
Haskell Engineering Co., Burbank, California
VHC 4-4 F (MV-2)
Size, Inches, and Type
of Connection
Sparklett Devices, Inc.
St. Louis, No. 3165
(X>2 Content : 26 gms net
1/4 NPT
1/4 NPT
1/8 NPT
1/8 NPT (Actuation) x
1/4 Swagelok
1/8 NPT (Actuation) x
1/4 Swagelok
1/8 NPT
1/4 AN X 1/4 AN X 1/8
NPT on the side
1/4 AN X 1/4 AN X 1/8
NPT on the side
1/8 NPT x 1/8 NPT
1/8 NPT x 1/8 NPT
1/8 NPT x 1/8 NPT
1/4 NPT x 1/4 Swagelok
1/8 NPT x 1/4 Swagelok
1/8 NPT x 1/4 Swagelok
1/8 NPT x 1/4 Swagelok
1/8 X 1/8 x 1/8 NPT
Female
1/4 NPT street-L
1/8 x 1/4 NPT
1/4 NPT to 1/4 AN
1/4 NPT to 1/4 AN
1/4 x 1/4 NPT
3/8 x 1/4 NPT
3/8 X 1/4 NPT
1/4 x 1/8 NPT
1/4 x 1/8 NPT
1/4 NPT (male run)
1/4 NPT (male run)
1/4 NPT
1/4 NPT
Male 1/4 NPT
Male 1/4 NPT
Male 1/4 NPT
Male 1/4 NPT
Female 1/4 NPT
Derating
ressure,
psi
1200
1200
200 to
70
250
250
250
250
250
70
70
250
70
70
70
70
70
70
250
1500
1500
250
250
250
250
250
250
250
250
250
250
250
250
250
250
Miscellaneous Data
Drill out exit fitting 1/8-inch
bore
Expendable
With 0 to 600-psi gage
're- set at factory to 70 psig
tein operation valve. Located on
handle.
formally closed
Normally closed
Set at 30 cph with CN2 at 230 psig
Common pipe type can be substituted
Common pipe type can be substituted
4ust hold 250-psi gas pressure
Common pipe type can be substituted
Common pipe type can be substituted
Required to withstand 300-psig gas
Use 0-ring, MS28778-4, Compound
N507-9
Identical to No. 46, 47, and 48
(see Note 2) Used for large tandem
cylinder only
Used for large tandem cylinder only
If large cylinder is used, specify
3/8 x 1/8
If large cylinder is used, specify
3/8 x 1/8 (see Note 2)
Set at 120 psig (see Note 1)
Set at 120 psig (see Note 1)
Refill port for polyole
Refill port for Isocyanate
Discharge port for polyole
Discharge .port for Isocyanate
Discharge port for mixing gas
Parts List EPA Contract: 68-03-0234
92
-------
TABLE A-l. (Continued)
NAME: LARGE DELIVERY SYSTEM
Item
No.
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
101
103
104
107
110
112
113
115
118
119
120
130
131
132
133
134
Item Function
Tandem Cylinder
B-Nut Tee
B-Nut Elbow
B-Nut Elbow
Pipe Tee
Pipe Tee
Nipple
Nipple
Nipple
Special Elbow
Pressure Relief Valve
Base Plate
Bracket Shaft End
Bracket Closed End
Cylinder Support Nut
Gas Supply Tube
Gas Supply Tube
Gas Supply Tube
Gas Vent Tube
Mixing Gas Tube
Vent Tube
Actuation Gas Tubing
Actuation Gas Tubing
Pipe Cross
Quick Disconnect
Valve Nipple
Quick Disconnect
Valve Nipple
Pipe Coupling
Nipple, Pipe, and Tube
Hose Adapter
Hose adapter
Hose Clamp
Delivery Tube Assembly
Gas Delivery Tube
Long Delivery Tube
Spacer, Longitudinal
Spacer, Radial
Spacer Elbow
Spacer Tee
Tube Clanp
Manufacturer and Part Number
Allenair Corporation, Mineola, New York,
Type BT-BC-HTP
Parker-Haiinifin Corporation, Cleveland, Ohio
4-R6BX S.S.
Parker-Hannifin Corporation, Cleveland, Ohio
AA-67028-4K S.S.
Parker-Hannifin Corporation, Cleveland, Ohio
AA-67028-4K S.S.
Airdrome Parts Co., Long Beach, California
AN-917-2 S.S.
Airdrome Parts Co., Long Beach, California
AN-917-2 S.S.
Airdrome Parts Co. , Long Beach, California
AN-911-2 S.S.
Airdrome Parts Co., Long Beach, California
AN-911-2 S.S.
Airdrome Parts Co. , Long Beach, California
AN-911-2 S.S.
Airdrome Parts Co. , Long Beach, California
AN-822-4 MS-20822-fJ
Teledyne Republic, Cleveland, Ohio
R-4 627B-4-1/4-28
Constructed from 1/8-inch aluminum sheet
Constructed from l/8~inch aluminum sheet
Constructed from 1/8-inch aluminum sheet
Material is part of purchased tandem cylinder
Constructed from copper tubing
Constructed from copper tubing
Constructed from copper tubing
Constructed from copper tubing
Constructed from copper tubing
Constructed from copper tubing
Cadillac Plastics Co., North Hollywood, California
No. 0112 polypropylene tubing
Cadillac Plastics Co., North Hollywood, California
No. 0112 polypropylene tubing
Airdrome Parts Co., Long Beach, California
AN-918 S.S.
Haskell Engineering CO. , Burbank, California
VHN 4-4 H (MV-2)
Haskell Engineering Co., Burbank, California
VHN 4-4 MMV
Commercial Hardware Supplier, Brass
Airdrome Parts Co., Long Beach, California
AN 816-4-4 S.S.
Ryan-Herco Products Co., Burbank, California
0700-162 polypropylene
Ryan-Herco Products Co., Burbank, California
0700-162 polypropylene
Ryan-Herco Products Co., Burbank, California, S.S.
Constructed from metal tubing S.S.
Ryan-Herco Products Co., Burbank, California
No. 0030-071, Tygon Innerbraided Tubing
Van Mater and Rogers, San Francisco, California
Rubber tubing
Ryan-Herco Products Co., BurbanX, California
1/4-diameter, schedule 80 pipe
Ryan-Herco Products Co., Burbank, California
1/4-diameter, schedule 80 pipe
Ryan-Herco Products Co., Burbank, California
No. 3806-002 1/4-inch elbow
Ryan-Herco Products Co., Burbank, California
No. 3801-002 1/4-inch tee
Ryan-Herco Products Co., Burbank, California
1/4-inch diameterT schedule 80 pipe
Size, Inches, and Type
of Connection
2-1/2 x 4, large
2x3, small
B-Nut, Run Tee, 1/4 AN
B-Nut El, 90-degree
1/4 AN
B-Nut El, 90-degree
1/4 AN
1/4 NPT, Tee
'l/4 NPT, Tee
1/4 x 1/4 NPT
1/4 x 1/4 NPT
1/4 x 1/4 NPT
1/4 AN x 1/8 NPT El
1/4 NPT, 250 psi
maximum
As per Note 6
As per Note 6
Modify as per Note 7
Part of Item 40
1/4-diameter, 0.035 wall
1/4-diameter, 0.035 wall
1/4-diameter, 0.035 wall
1/4-diameter, 0.035 wall
1/4-diameter, 0.035 wall
1/4-diameter, 0.035 wall
1/4 diameter x 10 feet
long
1/4 diameter x 10 feet
long
1/4 NPT
Male 1/4 NPT
Male 1/4 NPT
1/4 NPT
1/4 NPT x 1/4 AN
1/4 NPT to 3/8 hose
1/4 NPT x 1/2 hose
1/4 0750-004
1/4 x 0.035 wall
3/8 ID x 5/8 OD
Material PVC
Material PVC
Material PVC
Material PVC
Modify as per Note 3
Operating
Pressure
psi
250
250
250
250
250
2SO
250
250
250
250
250
50
50
SO
50
50
50
50
SO
Miscellaneous Data
See Note 5
Set at 250 psi which is maximum
See drawings for this part
See drawings for this part
See drawings for this part
Two required
Two required
Two required
Two required
Two required
Two required
Two required
One required
One required
Two required
Two required
Two required
One required
One required
Two required
Constructed fron tubing, B-nuts,
and rings, two required
Approximately 7 inches long
100 inches long
8-3/4 inches long, two required
5-3/4 inches long, two required
Two required
One required
Cut to length (1-1/2 inches),
one required
Parts list EPA Contract: 68-03-0234
93
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TABLE A-l. Continued)
NAME: LARGE DELIVERY SYSTEM
Item
No.
201
202
203
204
205
207
208
301
302
303
Item Function
Applicator Main
Delivery Tube
Reticulated Foam
Sealant (silicone)
Twine
Rubber Bag (membrane)
Vent Tube
Hose Clamp
Handle
Valve Bracket
Applicator Clamp
Manufacturer and Part Number
Tube Sales, Los Angeles, California
Metal tubing S. S.
Commercial Hardware Dealer, Made from polyurethane
foam mattress material
General Electric, RTV-106 (white) RTV-102 (red)
Nylon tie cord, waxed
Sherwood Medical Inc., Pioneer Rubber Co.,
Division, Tiffin Road, Willard, Ohio, K-1225-N
Cadillac Plastics, Detroit, Michigan
Cellulose acetate butyrate tubing
Ryan-Herco Products Co., Burbank, California, S.S.
Tube Sales, Los Angeles, California
Aluminum box beam
Standard Steel, washer
Fisher Scientific, No. 1540
Size/ Inches and Type
of Connection
3/8 x 0.&35 wall tubing
5/16 OD x 1/4 ID
.5/8 inch
7/8 x 1-5/8 x 7-1/2
feet long
2-1/8 OD 1/2 ID x 1/8
thick
Operating
Pressure,
-psi
Miscellaneous Data
Drilled as per drawing
Used as required in assembly
Approximately 5-inch length per
applicator
Two required
The adjustable pressure relief valves called out as items 33 and 34 are mounted on the small tandem,-cylinder delivery system. The large system has
the Teledyne pressure relief valve identical to item 50 in place of items 33 and 34. However, for'new construction the valve described for items 33
and 34 is preferred for this use and is recommended for new construction instead of item 50.
NOTE 2:
Part No. 27, 28, 29, and 30 are used only to adapt the large cylinder which has 3/8-inch pipe ports to the other plumbing above these ports. The
small cylindfsr has 1/4-inch pipe ports.
The drawing of the mixing assembly has one dimensional change that is of basic importance when changing from a small to large tandem cylinder: i.e.,
the 7-3/8-inch (18.73-cm) dimension between the two outer quick disconnects should be changed to a larger dimension corresponding to the distance
between the two outlet ports on the large tandem cylinder, (see Note 5)
NOTE 3:
Spacer Subassembly Construction
1. Cut required number and lengths of schedule 80 PVC pipe as specified for Part No. 130, 131 and 134.
2. Cement Part No. 134 into Part No. 133 as shown on the assembly drawing using cement described as follows:
PVC Solvent Cement PIP205
Permalite Plastic Corporation
Newport Beach, California
3. After cement has set, drill along axis of tube (Part No. 134) 25/64-inch diameter and continue drilling through the back of the tee (Part No. 133).
4. Cut slots 1 inch deep, one on each side of Part No. 134 by making a hacksaw cut across the tube end as shown in assembly drawing.
5, Slip hose clamp [Part No. 115) over the slotted end of Part No. 134.
6. Slip the applicator tube through the hole in the tee and tighten the hose clamp to result in the arrangement shown in the Applicator Assembly
drawing.
NOTE 4:
S.S. stands for stainless steel
NOTE 5:
Item 40, the tandem cylinder, is changed to the following designation to construct a small delivery systei
Tandem Cylinder
Allenair Corporation
Mineola, New York
Type ET-BC-HTP 2x3
Large and Small Tandem Cylinders
The as-delivered hardware is equipped with a small cylinder for the mechanically actuated model which is mounted on a backpack rack. A cylinder having
twice the delivered volume capability of the small one is incorporated into the pneumatically operated unit. It is this latter unit which is described
in detail in drawing AP-75-002 and the accompanying parts lits. The drawing is different from the as-built pneumatic system in only one way; the tandem
cylinder depicted is the small size rather than the large size to illustrate the very close similarity between the designs when this simple subsituation
is made.
CAUTION: Note that when the cylinder size is changed, the distance between the outer tubes of the mixing assembly (7-3/8 inches in the
subject drawing) must also be changed to match the distance between the exit holes in the tandem cylinder. Thus, mixing subassenblies
are not interchangeable between large and small cylinders. Ultimately, this should present no problem in a production item, but is pre-
sented as a precaution until this is changed.
Calculated Volume Displacement during one stroke of the Tandem Cylinder.
Size
Small
Large
Manufacturing Designation Number
ET-BC-HTP 2x3
ET-BC-HTP 2-1/2 x 4
Cylinder With Rod Extending Through
cc cu in.
139.5 8.51
292.4 17.84
Cylinder Without Rod Extending Through
cc cu in.
206 12.57
321.6 19.63
Totals
cc cc in.
345. S 21.08
614 37.47
Parts List EPA Contract: 68-03-0234
94
-------
TABLE A-l. (Concluded)
NOTE 6:
Construct item No. 52 and 5! as shown:
NOTE 7:
Modify the nuts which are furnished with the tandem
cylinder as shown here.
(An alternate mounting method is shown on the large
drawing as regards the closed end of the tandem
cylinder only. However, this is not preferred.)
B£t/Et- -Xf &&S.
A-A
NOTE 8:
The pneumatically actuated system shown in Drawing AP-75-002 is applicable for construction of the mechanically actuated version (which is mounted
on a backpack) by making the following substitutions:
Omit the following items: Item No. 4, 14, 62, 45, 47, 48, 6, 56, 11, 19, 17, 61, 15, 16, 20, 5, 12, 7, 60, 58, and 302.
Add the following items: One each, three-way palm button valve; Norgen No. D0023A (Teglon Eng., El Monte, CA)
One each, control cable, standard automativS choke cable
One each, handle with actuating lever
One each, set of brackets
One each, backpack frame
(see photograph No. 5A631-1/13/75-S1C)
NOTE 9:
The chemicals for filling the tandem cylinder are obtained in pressurizable cylinders from:
01 in Corp.
P.O. BOX 847
Benicia Park
Benicia, CA. 94510
The chemicals are designated as No. 202-C1
The "fast" foam referred to in the text of this report has the designation: Olin No. X 721102.
Parts List EPA Contract: 68-03-0234
95
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APPENDIX B
REFILLING THE FOAM DELIVERY SYSTEM
The following is a description of the equipment and of the procedure used
to refill the foam delivery system. The baseline urethane foam system is
designated No. 202-C1 by the 01in Company. Therefore, the instructions
below were derived from information provided by that supplier. Instruc-
tions provided by the supplier of alternate foam systems should be obtained
and followed where applicable.
DESCRIPTION
The flow diagram in Fig.B-1 shows the basic equipment normally used for
refilling the portable foam delivery system tandem cylinders. The chem-
icals are contained in pressurized cylinders with the isocyanate component
(or A component) color-coded WHITE and the polyol component (or B compo-
nent) color-coded BLACK. Caution: These cylinders are under pressure
when delivered.
The complete system (Fig.B-l) consists of component cylinders, which are
pressurized by the nitrogen supply, causing material to pass through the
component hoses, to the filters, and to the quick disconnects which are
later plugged into the mating disconnects on the delivery system to be
filled.
CHEMICAL PREPARATION HANDLING AND STORAGE
These are instructions from 01in Corporation for their use of the foam
chemicals in their commercial foam delivery system.
Temperatures:
1. Material cylinders should never be stored at temperatures below
21 C (70 F) or above 32 C (90 F).
2. For optimum operation, material temperatures in the cylinders
should be above 24 C (75 F) and below 32 C (90 F).
3. These temperature ranges are critical as they can affect the re-
activity of the foam systems.
96
-------
FLOW DIAGRAM
^ ,
i ^
itrogen
/*^\ Regulator
Temperature Block*—** ~ j^p^
«1
lj
•l
II
"B" Component ||
Cylinder ||
|l
II
H
U
"B" Component t
Hose
,•
1
Ball Valve d ^
a
1
Quick-Disconnect _ — — - \
1
T-. Nitrogen
Supply
,
^n **>.•'/
'
\
\ 1
ri w
* xj
i
1 1
rf
ii ^
*
n
''
'! "A" Component
• Cylinder
M
II
II
U
"A" Component
Hose
ty///A "A" Component
ra b>\\sVj "B" Component
Filter
Figure B-l. Schematic Diagram of Equipment to Refill
Foam Delivery System
97
-------
Mixing;
The Autofroth I foam chemicals (foam chemicals 202-C1 were used
in this project) are completely premixed at the Olin producing
plant, however, quantities should be ordered as indicated by
the requirements of your operationt Cylinders should not be kept
in investory for periods exceeding 6 months.
Nitrogen:
1. When properly used, one 220-cubic foot nitrogen cylinder will
service approximately 1000 pounds of Autofroth foam.
2. When the nitrogen pressure, as indicated on the pressure gage,
falls below 240 psi, replace or recharge the nitrogen cylinder.
The system will not operate below a constant pressure of 220 psi.
3. USE ONLY DRY NITROGEN FOR CYLINDER PRESSURIZATIQN (i.e., oil
pumped. Water-pumped nitrogen is not suitable).
CAUTION:
Excessive direct heat should never be applied to any cylinder. To
bring the chemicals contained in the cylinders up to operating tem-
peratures, they should be placed in a warm environmental room, or
box, for a period sufficient to allow a gradual warming of the
chemicals.
INSTALLATION
Cy1inder Preparat ion:
1. Ensure that the two (one white and one black) material component
tanks are placed together in the same environmental temperature.
Chemical component temperatures should be at a minimum of 21 C
(70 F) and a maximum of 32 C (90 F). Bear in mind that these
temperature restrictions are parameters with the ideal tempera-
ture somewhere around 25 C (80 F).
2. Ensure that all ball valves on the material cylinders are in the
off position.
3. Remove hexagon-shaped sealing caps from the top of each tank,
making sure that the ball valve and dip leg assembly ate held in
place and do not turn. Clean with methylene chloride if required.
Apply a thin film of silicpne grease, vaseline, or othei1 lubri-
cating-type oil to the thread area before connecting the matching
female assembly.
4. Ensure that the hose connections are tight at the gun and the
filters. Position BLACK manifold temperature block on the black
tank and complete the attachment with the disconnect fitting
from the nitrogen tank. Position WHITE temperature manifold
98
-------
block on the white tank and attach its appropriate nitrogen pres-
surization fitting. Tighten the nuts gently with a wrench until
connectors are fully engaged. When fully engaged the manifold
blocks will not rotate and the hose will not move. ALWAYS DOUBLE
CHECK THE TANK COLOR-CODE BEFORE CONNECTING.
5. Cylinders should never be brought to higher temperatures while in
a pressurized condition. If cylinders have been pressurized to
the 250-psi working pressure, and it is determined that the foam
chemicals must be further heated, IT IS IMPERATIVE THAT THE PRES-
SURE BE RELIEVED TO 75 PSI BEFORE HEATING. A 590-915 Pressure
Relief/Transfer System is available for this purpose.
6. Ensure that the valves at the ends of the delivery hoses are
turned off; then turn the ball valves on the cylinders to the
open position.
Sealing Empty Cylinders for Return:
1. Always ensure that the sealing dust caps are tightly screwed onto
the male connectors and the quick disconnector dust caps are in
place on the tanks when they are not in use. This is essential
to prevent possible contamination and vapor leak from the con-
nectors. Make sure the threads and ball cage of all fittings are
clean and well lubricated before replacing caps.
2. Empty cylinders returned for refilling must also be sealed,
cleaned, and pressure relieved to 50 psi. Failure to seal the
empty tanks upon return will result in additional servicing with
such charges deducted from the tank deposit.
Nitrogen Connection:
1. Make sure all fittings and hose connections are attached and
tightened to the nitrogen regulator.
2. With the valve on the nitrogen bottle in the open position, first
connect the nitrogen to the white material tanks. A surge of
nitrogen should be noted indicating that the pressure is building
in that cylinder. This eliminates the possibility of a frozen
tank fitting which occasionally occurs only on the white tank.
Also, by connecting the fitting while the nitrogen is in the open
position, this eliminates any chance of material from a full tank
flowing into the connections.
3. Connect the remaining nitrogen lines to the rest of the system
and pressurize until equilibrium of nitrogen pressures has been
obtained. Ensure that there is 240 psi minimum on each cylinder
and that there is a reserve of nitrogen in the nitrogen tank.
4. On the larger Autofroth cylinders there is a ball valve below the
nitrogen tank fitting. Be sure the ball valve is turned to the
open position during hook-up and when operating. Also ensure
that you are using dry nitrogen ONLY.
99
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OPERATION
When the recharging equipment is ready for use, but before connecting it
to the system to be filled, obtain several disposable plastic bags for
catching waste foam chemicals. Plug a spare quick disconnect into the end
of each delivery hose (Part No. 35, Appendix A). This opens the check
valves in the quick disconnects and will allow chemicals to flow out freely
when the ball valves are opened. After placing the tip of the Chemical A
delivery hose in a plastic bag, very slowly and carefully open the system
A ball valve, allowing any trapped air or gas to escape from the delivery
line and momentarily allowing the chemical following it to gush out. As
soon as the chemical flows freely from the tip, close the ball valve and
flush the chemical from inside the quick disconnect with solvent. Repeat
the above for Chemical B delivery line. Now remove the spare quick dis-
connects from the tip of each delivery line and set them aside for clean-
ing and then storage. The above flushing operation needs normally to be
done only when the equipment is new or after an extended time of several
weeks inactive storage.
Actuate the delivery system to be filled to ensure that as much as possible
of the residual chemicals remaining in the main cylinder have been expelled.
(Be sure to remove the flushing hoses before proceeding to the next step.)
Now connect the quick disconnects on the end of each fill line to the cor-
responding female quick disconnects on the delivery system after first
checking to see that they have not been inadvertently reversed. The polyol
should be connected to quick disconnect No. 35 and the isocyanate to quick
disconnect No. 36.
CAUTION: Should liquid A be allowed to flow into the liquid B
system, the resulting reaction will render the system useless
in a matter of seconds and the tandem cylinder probably will
have to be discarded.
PAY ATTENTION TO THE COLOR CODE. Connect back to black (component B,
polyol), and white to white (component A, isocyanate). (An obvious and
simple manufacturing improvement would be to provide a foolproof method
whereby it would be impossible for the operator to make the mistake men-
tioned above.)
Check that the cylinder on the delivery system has been vented. (Actua-
tion Valve, Part No. 5, is in vent position). Now open the two ball valves
nearly simultaneously, with component B leading component A by approxi-
mately 1 second. This will cause the shaft to travel out of the cylinder
as the pistons are displaced by the incoming liquid chemicals. Allow the
system to remain with the ball valves open for 3 minutes; then close them and
carefully disconnect the fill lines at the quick disconnects.
Next, connect two bleed lines to the two quick disconnects (37 and 38)
These bleed lines conduct excess material trapped between quick disconnects
33 and 37, and between 34 and 38 into waste containers provided for this
purpose. This step is taken so that this material will not prematurely
100
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flow into the mixing subassembly when these units are interconnected later
in the field. After waiting a few minutes for the chemicals to stop flow-
ing out of the bleed lines, remove them.
Flush out the disconnects with solvent several times,* each time removing
excess solvent by blowing out the disconnect with compressed air or
nitrogen.
CAUTION: This should be done under a hood or with good venti-
lation to prevent personnel from inhaling the fumes.
When first using a new system, the flowrate of nitrogen gas through the
needle valve (8) should be checked with a flowmeter to be 30 scfh (stand-
ard cubic feet per hour) for the small delivery system and 45 scfh for the
large delivery system at a pressurant level of 250 psig. If incorrect,
adjust needle valve (8) until proper flow is obtained.
The delivery system is now recharged and ready for reuse.
MAINTENANCE
Component parts, whenever disassembled, should be thoroughly cleaned im-
mediately in methylene chloride. If the part or the unit is not to be
used for extended periods, apply a light coat of lubricating oil on the
exposed portions of the system after a thorough cleaning.
The isocyanate, (i.e., component A, color-coded white) will react with the
moisture in air in a matter of hours to form a very tough, solvent-resisting
material. Do not let air enter components to be reused if at all possible.
If air does enter, flush the delivery system by filling and emptying it twice.
CAUTION: NEVER disconnect any hoses or other parts of the fluid
system while hoses are connected to tanks and the cylinder ball
valves are in the on position. Whenever temperature manifold
blocks are removed from cylinders, be sure cylinder ball valves
are in the off position.
To clean the filter, disassemble it, remove the filter screen, and flush
thoroughly in clean solvent. Then, reassemble it.
*Viton seals should be allowed to remain in contact with methylene chloride
for as SHORT a time as possible to prevent swelling.
101
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/2-76-300
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
Prototype System for Plugging Leaks in Ruptured
Containers
5. REPORT DATE
December 1976 issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
J. J. Vrolyk, R. C. Mitchell, and R. W. Melvold
8. PERFORMING ORGANIZATION REPORT NO.
R-9659
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Rocketdyne Division
Rockwell International Corporation
Canoga Park, California 91304
10. PROGRAM ELEMENT NO.
1BB610
11. CONTRACT/GRANT NO.
EPA 68-03-0234
12. SPONSORING AGENCY NAME AND ADDRESS
Industrial Environmental Research Laboratory-Gin., OH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
EPA/600/12
15. SUPPLEMENTARY NOTES
16. ABSTRACT
A development program was performed successfully to develop and test a prototype
system for temporarily stopping the flow of hazardous materials spilling on land or
underwater from ruptured or damaged containers. The prototype system is portable,
integrated, and field-operable by one man. It uses foamed-in-place polyurethane
rigid foam plugs surrounded by a flexible protective membrane for sealing leaks.
An applicator tip attached to a long handle is placed into the leak. The foam
delivery system then is actuated and the foam chemicals, which are stored in a back-
pack, are automatically mixed and forced through a delivery tube and into the
applicator tip expanding it both inside and outside the tank. The foam hardens
in a few minutes and locks the plug in place. The applicator is then detached
from the delivery system, which then can be refilled with foam chemicals and reused
with a new applicator.
The prototype leak-plugging system from this project has been developed to the
point that it is now realistic to project practical field use of such a system, A
preliminary implementation plan, including recommendations for additional work
needed, is outlined. (Mitchell - Rocketdyne)
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Water Pollution, Accidents, Hazardous
Materials, Transportation, *Sealants,
*Chemicals, *Leakage
Hazardous Chemical
Spills, Prevention of
Water Pollution,
*Plugging Chemical Leaks
13B
8. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport)'
Unclassified
21. NO. OF PAGES
110
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
102
U. S. GOVERNMENT PRINTING OFFICE 1977-757-056/5591 Region No. 5-11
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