United States
Environmental Protection
Agency
Hazardous Waste Engineering
Research Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-87/041 July 1987
&EFA Project Summary
Calibration and Evaluation of a
Dispersant Application System
J. S. Shum
Summarized herein is a final report
which presents recommended
methods for calibrating and operating
boat-mounted chemical dispersant
application systems. Calibration of one
commercially available system and
several unusual problems encountered
in calibration are described. Charts and
procedures for selecting pump rates
and other operating parameters needed
to achieve a desired dosage are pro-
vided. The calibration was performed
at the EPA's Oil and Hazardous Mate-
rials Simulated Environmental Test
Tank (OHMSETT) facility in Leonardo,
NJ.
This Project Summary was devel-
oped by EPA's Hazardous Waste Engi-
neering Research Laboratory, Cincin-
nati, OH, to announce key findings of
the research project that is fully doc-
umented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
A chemical dispersant may be'used in
an oil spill when mechanical methods to
contain and recover the spilled oil are
not feasible because of weather condi-
tions or the size or location of the spill.
Successful use of a chemical dispersant
in an oil spill cleanup depends on the
effectiveness of both the chemical itself
and the application techniques. An
effective application requires properly
designed equipment and a good regula-
tion of dose rate.
The final report describes an evalua-
tion and calibration of a SEASPRAY 2*
dispersant application system. The
SEASPRAY 2 was selected because of
its commercial availability and certain
design features. It is light-weight, por-
table, self-contained, and versatile, with
good dosage control. It appeared to be
representative of 1984 state-of-the-art
design. The selected system was cali-
brated to demonstrate:
• The need for the calibration.
• How the calibration may be
performed.
• The use of the calibration data for
monitoring and control of the dispers-
ant application rate.
The SEASPRAY 2 was calibrated for
installation and use on board the EPA's
Region 2 vessel CLEAN WATERS. The
calibration was conducted at the EPA's
Oil and Hazardous Materials Simulated
Environmental Test Tank (OHMSETT)
facility in Leonardo, NJ.
Equipment
The SEASPRAY 2 consists of a pump
unit and two spray arms. The accessory
items include hoses, suction pipe,
mounting hardware, and securing stays.
The pump unit consists of an electric-
start diesel engine and interconnecting
piping. The entire unit is mounted in a
•SEASPRAY 2 is the tradename of Delavan Ltd.,
Widnes, England, and is supplied by Frank Ayles
& Associates Ltd., London, England. Mention of
tradenames does not constitute endorsement of the
product by the U.S. Environmental Protection
Agency.
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• Static head at pump discharge to the
spray holders.
The suction lift and discharge head
were kept fixed during the calibration.
The relative elevations of the equipment
components during the calibration were
set up to provide a suction lift and static
head similar to that expected at the
proposed installation. The pump
elevation was approximately 2273 mm
(89.5 in.) above the water level. The two
spray arms were 152 mm (6 in.) above
the pump base.
The suction lift for dispersant chemical
under normal operation varies with the
liquid level in the dispersant drum. The
suction lift, being minimum with a full
drum, increases as the dispersant is
pumped out. The calibration was per-
formed with a constant liquid head that
is representative of an average suction
lift for a full-to-empty drum.
Different fluids of various viscosities
were used to calibrate the flow meter.
The different fluids were also used to
determine the system's dispersant appli-
cation rate as a function of viscosity in
undiluted spraying mode. These fluids
were salt water from OHMSETT's test
tank and different oils obtained by
blending Circo 4X light and Circo medium
oils in various proportions.
Results and Discussion
The calibration was conducted on two
separate occasions. The results from the
initial calibration show that the nozzle
flow rates varied significantly along the
length of the two spray headers. Inspec-
tion of the nozzle internals after the
calibration showed several nozzles had
defective orifices. In general, the orifices
were not completely drilled through the
plates. Foreign materials were also found
in some of the nozzles.
The SEASPRAY 2 was recalibrated
after modifications were made to correct
the observed problems. All the defective
orifice plates in the nozzles were
replaced. Also, a filter strainer was
installed at each of the pump discharge
ports.
Calibration of the SEASPRAY 2 shows
that the manufacturer-supplied flow
meter has a positive bias indication. The
50-cS scale is biased an average 0.23
mVh (1 USGPM), or 11% of full scale.
The meter performed better with the
lower-viscosity fluid, resulting in an
average bias of 0.005 mVh (0.2 USGPM)
or 2% of full scale. The 100-cS scale
average bias is 0.09 mVh (0.4 USGPM)
or 4% of full scale.
stainless-steel tubular frame. Figure 1
shows a schematic of the piping arrange-
ments. The inlet and discharge con-
nections have cam-lock couplings for
quick connections to the sea water
intake, the dispersant supply, and the
discharges to the spray headers. A
separate priming port is provided for
startup. A pressure gauge and a
pressure-relief valve at the pump dis-
charge manifold provide indication and
adjustment of the discharge pressure to
the spray headers.
The spray arms consist of two 6-meter
(20-ft) long assemblies. Each assembly
has a spray header and a fiberglass
reinforced plastic structure for support.
There are seven, spray-nozzle connec-
tions on each spray header. Two types
of nozzles are available for use. For
diluted spraying mode, seven Model
QLD-30 nozzles are fitted on each spray
arm. For undiluted spraying mode, four
Model QLD-10 nozzles are fitted on each
header, and the remaining connections
are blanked off. The nozzles produce flat
spray patterns.
Method
The calibration was conducted with the
equipment set up outdoors on the wash
pad at the north end of the OHMSETT
test tank. The calibration program con-
sisted of calibrating the measurement
instruments and the SEASPRAY 2 dis-
persant application system. The system's
dispersant application rates under dil-
uted spraying and undiluted spraying
were determined. The indicating devices
(i.e., the flow meter and the pressure
gauge) on the SEASPRAY 2 were also
calibrated.
Many operating variables affect the
performance of a dispersant application
system. The author attempted to cali-
brate the SEASPRAY 2 operating at or
near the design specifications. Following
are the variables considered in the
calibration setup:
• Pump discharge pressure to the spray
headers.
• Fluid viscosity and/or specific gravity.
• Pump suction lift.
Pressure Relief _
Valve
Discharge to
Port Spray Arm .
Pressure
Gauge
Discharge to
Starboard Spray Arm.
Pump
£ Kea I
r
Sea Water Suction/Dispersant
Suction (Neat Spraying)
Eductor
Flow Meter
, Dispersant Control
Valve
Dispersant Suction
(Mixed Spraying)
Figure 1. Piping schematic of the pump unit. The spray headers and the nozzles are not
shown in this figure.
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In diluted spraying mode, the mea-
sured nozzle flow rates agreed well with
the manufacturer's published data. The
maximum dispersant eduction rate
appeared to be limited by the upper range
of the flow meter scale which is 1.95
mVh (8.58 USGPM). Figures 2 and 3
(from the flow meter calibration data)
show the dispersant flow rate versus
flow meter reading.
In undiluted spraying mode, the nozzle
flow rate varied linearly with the fluid
viscosity. The flow meter is not used with
undiluted spraying. The maximum dis-
persant application rate is limited by the
fluid viscosity. At high fluid viscosity
(above 200 cS), the pump operation was
accompanied by severe vibration. Also,
the spray angle decreased from approx-
imately 90° for salt water to approxi-
mately 30°-40°. Figure 4 shows the
undiluted dispersant application rate
versus dispersant viscosity.
Figure 5 shows the relationship
between dispersant application rate and
the vessel speed for various unit area
dosage. This figure was developed for the
proposed equipment installation. The
operating procedures to maintain a
correct dispersant application dosage (in
liters per hectare or gallons per acre) are:
• For Diluted Dispersant Spraying—The
operator selects a vessel speed and
determines the required dispersant
application rate from Figure 5. The
operator then adjusts the flow meter
to obtain the application rate using the
flow meter calibration curves (Figures
2 and 3).
• For Undiluted Dispersant Spraying—
The flow meter is not used. The
operator must vary the speed of the
vessel to control the application
dosage. Figure 4 is used to determine
the dispersant flow rate. The operator
then determines and maintains the
vessel speed as shown in Figure 5.
Conclusions
The study demonstrates that any new
dispersant application system should be
calibrated before one can be sure that
the equipment will perform as expected.
Dispersant application rate estimates
based on the spray nozzle manufactur-
er's published data may be erroneous
due to production variance or defective
product parts. Fluid viscosity under
actual application conditions may also
affect the equipment's spraying perfor-
mance. Manufacturer's installed instru-
ments, such as flow meters and pressure
o.a
Figure 2.
2.6
2468
50 CS-Scale Reading
Dispersant flow rate versus flow meter reading on the 50-cS scale.
2.4-
2.2-
2.0-
1.8-
1.6-
1.4-
1.2-
1.0-
0.8-
0.6-
0.4-
0.2-
0.0
Figure 3.
Fluid Viscosity 80-110 CS
) 2 4 6 8
100 CS-Scale Reading
Dispersant flow rate versus flow meter reading on the 100-cS scale.
10
gauges, should also be checked and
calibrated. The nozzles should have
provisions to access the internal parts for
inspection and cleaning. To minimize
potential nozzle plugging, liquid strain-
er(s) should be provided at the pump
discharge.
Once the calibrating data are obtained,
operating charts relating various operat-
ing parameters and the application
dosage can be developed. For equipment
with flow meters, the correct dosage is
applied by determining the required flow
rate from the operating charts and
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2.0-
1.9-
1.8-
1.7-
1.6-
1.5-
1.4-
5 1.3-
\ 1-2-
* 1.1-
-Si 0.9-
0.7-
0.6-
0.5-
0.4-
0.3-
0.2-
0.1-
0.0-
Figure 4.
—1 \ \ \ 1 1—
40 80 120
Fluid Viscosity CS
160
—\—
200
—1—
240
Undiluted dispersant application rate versus dispersant viscosity at a pump
discharge pressure of 276 kPa (40 psi) gauge.
adjusting the flow meters accordingly.
When there is no flow meter, application
of the correct dosage requires control of
the vessel speed.
Calibration of the SEASPRAY 2 shows
that:
• The manufacturer-supplied flow
meter has a positive bias indication.
Use of the meter without calibration
will overestimate the application rate.
• For low viscosity fluids, the measured
nozzle performance agrees well with
the manufacturer's published data.
For higher viscosity dispersants used
in undiluted spraying, calibration is
required to establish the system's
performance.
• The pump unit is not suitable for
applying high viscosity dispersants.
With viscosities above 200 cS, severe
pump vibration will occur. Also, the
spray angle will be significantly
smaller than that specified by the
manufacturer.
• In diluted spraying mode, the disper-
sant application rate can be adjusted
with the flow meter over a range of
0 to approximately 2 m3/h (8.8
USGPM). This represents a unit area
dosage of approximately 0-104 liters/
hectare (0-11 USGPA) for the pro-
posed installation at a vessel speed
of 5 knots.
• In undiluted spraying mode, the flow
meter is not used. The dispersant
application rate is not readily adjus-
table. Maintenance of correct vessel
speed is necessary to obtain the
desired area dose rate. The operating
range of the application equipment in
undiluted mode for a low viscosity
dispersant is approximately 91 liters/
hectare (9.7 USGPA) at a vessel speed
of 5 knots.
This study was conducted at the EPA's
Oil & Hazardous Materials Simulated
Environmental Test Tank (OHMSETT)
facility in Leonardo, NJ. The full report
was submitted in fulfillment of Contract
68-03-3203, Work Assignments No. 121
and 137 by Mason & Hanger-Silas
Mason Co., Inc., under the partial
sponsorship of the U.S. Environmental
Protection Agency. The American Petro-
leum Institute was the co-sponsor.
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10 12 14 16 18 20
0.0
Figure 5. Vessel speed and dispersant application rate for various unit area dosage. For
the proposed installation configuration with a swath width of 20.7 m (68 ft) and
90° spray angle.
For intermediate values, use:
Vessel Speed (kt) x Swath (m) x Area Dosage (liters/ha)
Dispersant =
Rate (m3/hj
5397
Dispersant =
Rate (GPM)
Vessel Speed (ktj x Swath (ft) x Area Dosage (GPA)
430
J. S. Shum is with Mason & Hanger-Silas Mason Co.. Inc., Leonardo. NJ07737.
Richard A. Griffiths is the EPA Project Officer (see below).
The complete report entitled "Calibration and Evaluation of a Dispersant
Application System." (Order No. PB 87-194 213/AS: Cost: $13.95. 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:
Releases Control Branch
Hazardous Waste Engineering Research Laboratory—Cincinnati
U.S. Environmental Protect/on Agency
Edison, NJ 08837
A U.S. Govtrnnwnt Printing office: 19«7—741-012/67192
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United States Center for Environmental Research
Environmental Protection Information
Agency Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S2-87/041
f»S
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