United States
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
Las Vegas NV 89193
Research and Development
EPA/600/S4-87/016 Aug. 1987
&EPA Project Summary
Survey of Vendors of External
Petroleum Leak Monitoring
Devices for Use with Underground
Storage Tanks
B. Eklund and W. Crow
Underground storage tanks (UST's)
and their associated piping are major
potential sources of environmental
contamination. Since the 1984 Amend-
ments to the Resource Recovery and
Conservation Act (RCRA) require regu-
lation of underground storage tank
systems, the U.S. Environmental Pro-
tection Agency (EPA) is currently in-
vestigating topics related to UST's to
aid in developing regulations. EPA has
contracted with the Radian Corporation
to compile information on the various
types of external (out-of-tank) moni-
toring systems or techniques which can
be used to detect leaks or spills of
petroleum hydrocarbon products. The
compiled data were used to categorize
external petroleum leak monitoring
devices or techniques by functions and
type, and the data will aid in the future
development of uniform performance
criteria for commercially available ex-
ternal leak monitoring methods. The
present study, which is limited to ex-
ternal (outside-the-tank) petroleum leak
monitoring devices, supports the EPA
effort by providing information on the
number, type, and performance capa-
bilities of available leak monitors.
The literature was searched to collect
general information on external petro-
leum leak monitors and, more specifi-
cally, to develop a list of vendors.
Additional information was collected
from equipment vendors, trade groups,
and other researchers.
This Project Summary was devel-
oped by EPA's Environmental Monitor-
ing Systems Laboratory, Las Vegas,
NV. to announce key findings of the
research project that is fully docu-
mented in a separate report of the same
title (see Project Report ordering
information at back).
Introduction
Underground storage tanks (UST's) and
their associated piping are major potential
sources of environmental contamination.
Since the 1984 Amendments to the
Resource Recovery and Conservation Act
(RCRA) require regulation of underground
storage tank systems, the U.S. Environ-
mental Protection Agency (EPA) is cur-
rently investigating topics related to UST's
to aid in developing regulations. EPA has
contracted with the Radian Corporation
to compile information on the various
types of external (out-of-tank) monitoring
systems or techniques which can be used
to detect leaks or spills of petroleum
hydrocarbon products. The compiled data
were used to categorize external petro-
leum leak monitoring devices or tech-
niques by function and type, and the data
will aid in the future development of
uniform performance criteria for com-
mercially available external leak moni-
toring methods. The present study, which
is limited to external (outside-the-tank)
petroleum leak monitoring devices, sup-
ports the EPA effort by providing informa-
tion on the number, type, and performance
capabilities of available leak monitors.
Procedures
The literature was searched to collect
general information on external petroleum
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leak monitors and, more specifically, to
develop a list of vendors. Additional in-
formation was collected from equipment
vendors, trade groups, and other re-
searchers. A questionnaire soliciting in-
formation on leak monitoring devices was
developed and sent to the identified
vendors. The questionnaire covered six
topics: principle of operation, detection
specificity, detection capability, experi-
ence, cost, and recommended procedures.
The vendor list included vendors of LIST
monitoring systems and detectors that
could potentially be used for the detection
of petroleum hydrocarbon leaks or spills.
It should be noted that this survey does
not necessarily represent a complete list
of vendors that manufacture external
monitors for detecting petroleum leaks or
spills from underground storage tanks
and piping. Some vendors were likely to
have been inadvertently omitted, and
devices that are currently being marketed
could have changed since this survey
was performed. However, these data will
be useful in identifying the different
categories of commercial leak monitoring
devices and aiding in the development of
performance criteria for each monitoring
category. This report summarizes and
tabulates vendor responses to the ques-
tionnaire. The report also includes a dis-
cussion of related issues that remain to
be resolved before final performance
criteria can be established.
The data collection approach used in
this study has limitations. Reliance on
vendor-supplied data was necessary be-
cause of a lack of published, objective
evaluative test results. However, since
these vendor data have not been in-
dependently verified, it is possible that
some of these data are erroneous, biased,
or self-serving.
Conclusions
The literature search yielded relatively
little useful information on external leak
detection monitoring devices. The vendor
survey, however, was successful in gain-
ing information from approximately 70
percent of the vendors that were queried.
Except for a notable lack of data regarding
any common interference, operational,
or maintenance problems, vendor re-
sponses were generally thorough.
A total of 49 vendors was identified
that manufacture devices related to the
out-of-tank measurement of petroleum
hydrocarbon spills or leaks from UST
installations. Vendor specifications were
received for 63 of 69 (91 percent) dif-
ferent products. Survey forms were
completed by 30 of the 42 vendors that
were queried. Survey forms were received
for 44 of the 62 (71 percent) devices
covered by the survey.
Vendor responses provided a basis for
dividing the external (out-of-tank) leak
monitoring devices for UST systems into
four categories: intermittent liquid-phase
detection, intermittent gas-phase detec-
tion, continuous liquid-phase detection,
and continuous gas-phase detection. An
examination of vendor survey data yielded
the following information:
• Commercial external (out-of-tank)
leak monitors are designed primarily
to detect leaks or spills of petroleum
hydrocarbons;
• Most leak monitoring systems can-
not immediately distinguish between
surface spills and leaks;
• Most leak monitoring devices do not
measure leak rates, although some
devices (gaseous detectors) are
capable of measuring hydrocarbon
concentrations;
• No uniform performance specifica-
tions exist for external leak moni-
toring devices;
• Most leak monitoring systems re-
quire the installation of observation
wells or boreholes;
• Vendor responses were limited with
regard to:
— Operational problems,
— Interferences,
— Maintenance problems, and
— Performance testing procedures;
• Most leak monitoring systems can
be retrofitted at existing UST instal-
lations;
• Intermittent monitoring techniques
are more labor-intensive than con-
tinuous techniques, but may be more
reliable;
• Gas-phase detection can be more
sensitive than liquid-phase detection,
but the instrumentation may be more
subject to false alarms and subject
to interferences.
• Equipment and installation costs (for
permanent external leak detection
systems) may vary considerably as
these costs are dependent on the
type of devices selected and the
number of sensors used in each
installation, local construction codes
and permitting costs, and local labor
costs; and
• Operational and maintenance costs
for permanent external leak moni-
toring systems may vary also but are
thought to be low based on informa-
tion obtained from equipmen
vendors.
The performance characteristics fo
each leak detection category are sum
marized in Table 1. The data presented ir
Table 1 are based on information obtainec
from vendors and have not been verifiec
by independent testing; therefore, these
data may be biased.
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Table 1. Characteristics of Leak Detection Sensors
Leak Detection Category
Type of Compounds Detected
Detection Adjustable for
Specific Compounds
Potential Interferences
Severity of Interferences
False Positives or Negatives
Temperature Range
Can Systems Be Retrofitted?
Are Wells Required?
Can Devices Be Used in Wet Soils?
Years on Market
Detection Limits
Lower
Upper
Response Characteristics
Lag Time
Rise Time
Fall Time
Drift
Precision
Intermittent
Liquid-Phase
Liquid hydrocarbons
Generally not
None
Low
Unlikely
X)°C
Yes
Yes
Yes
>5
7/64 to 1/32 in.
None
N/A
N/A
N/A
N/A
N/A
Continuous
Liquid-Phase
Vapor/liquid
hydrocarbons
Generally not
Physical and chemical
Variable
Unlikely
-45 to 120°C
Yes
Usually
Yes
0-15
1/32 to 1/8 in.
None
1 sec. to 10 hr.
1 sec. to 60 sec.
1 sec. to ?
N/A
Unknown
Intermittent
Gas-Phase
Hydrocarbon vapors
Varies between
techniques
Chemical
Potentially high
Both possible
-20 to 60°C
Yes
Usually
Yes
2-10
0. 1 to 15OO ppm
20OOppm to 100% LEL
1 sec.
3 sec. to 30 sec.
5 sec. to ?
Negligible to <1%/ day
full scale
5% to unknown
Continuous
Gas-Phase
Hydrocarbon vapors
Generally not
Chemical
Potentially high
Both possible
-70 to 70°C
Yes
Usually
Yes
0-20
10 to 100 ppm
1% to 100% LEL
1 sec. to 10 min.
1 sec. to 20 sec.
20 sec. to several minutes
Negligible to <1%/day
full scale
5% to unknown
NOTE: The information presented in this table is based on information provided by vendors of monitoring devices and not on actual performance
data which has been independently verified.
B. Eklund and W. Crow are with Radian Corporation, Austin, TX 78766.
J. Jeffrey van Ee is the EPA Project Officer (see below).
The complete report entitled "Survey of Vendors of External Petroleum Leak
Monitoring Devices for Use with Underground Storage Tanks," fOrder No.
PB 87-212 346/AS; Cost: $18.95, subject to change) will be available only
from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Environmental Monitoring Systems Laboratory
P. 0. Box 93478
U.S. Environmental Protection Agency
Las Vegas. NV89193
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United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
.
"-
Official Business
Penalty for Private Use $300
EPA/600/S4-87/016
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