Current through Register Vol. 56, No. 24, December 18, 2024
(a) The
method for this section is applicable for the determination of the efficiency
of vapor recovery systems controlling gasoline vapors emitted during the
filling of underground storage tanks. For the same circumstances as described
above, any alternative method shall be submitted to the Department for review
pursuant to
N.J.A.C.
7:27B-3.2(c), (d) and
(e).
(b) This method is based upon the amount of
gasoline vapor discharged from the atmospheric vent(s) of underground storage
tank(s) being filled. The procedure is intended for all control systems which
have a vapor recovery line connecting the underground storage tank to the tank
truck.
(c) The following is a
summary of this method:
1. A positive
displacement meter is mounted on each atmospheric vent pipe to determine the
amount of vapor displaced during the filling of underground storage tanks. The
efficiency of the vapor recovery system is determined by comparing the amount
of vapor emitted from the atmospheric vents with the total amount of gasoline
transferred to the underground storage tanks.
2. For the purpose of this procedure, a
single test shall be sufficient to establish the efficiency of the vapor
recovery system.
(d) The
following is a list of equipment used in this method:
1. Gas meter device: a positive displacement
meter with a capacity of 3000 SCFH and a pressure drop of 0.05 inches of water
at an air flow of 30 SCFH. This meter shall be designed to read (in 0.1 cubic
foot increments) only the amount of positive vapors displaced and shall allow
for any negative in-breathing. The meter shall be equipped with taps for a
thermocouple and a pressure sensor;
2. Coupling for atmospheric vent pipe: a
coupling to connect the gas metering device to the atmospheric vent pipe.
Coupling shall be sized for a minimum pressure drop;
3. Thermocouples: temperature sensing devices
to measure the temperature of the vapors emitted at the gas metering device and
ambient temperature; and
4.
Manometer: liquid manometer or other equivalent pressure sensing device capable
of measuring zero to ten inches of water at the gas metering device.
5. Leak detection equipment standards shall
be as follows:
i. The leak detection
equipment shall be certified as safe for operation in explosive
atmospheres;
ii. The monitoring
instrument detector shall be capable of measuring the leak definition
concentration specified in the appropriate section in N.J.A.C. 7:27-16.
Detector types meeting this requirement include but are not limited to
catalytic oxidation, flame oxidation, infrared absorption and photoionization;
and
iii. The instrument shall be
readable to within five percent of the specific leak concentration and shall
have a response time of 30 seconds or less.
(e) The procedure for this section shall be
as follows:
1. Mount the positive
displacement meter to the top of the atmospheric vent of the storage tank(s).
If the vent has restriction, remove the restriction before mounting the
meter;
2. Connect the manometer and
thermocouple to the taps on the meter;
3. Connect tank truck fuel and vapor return
hoses to the underground storage tanks in accordance with procedures outlined
by the manufacturer;
4. Check the
tank truck and all vapor return line connections with a leak detection
instrument for a tight seal before and during the test;
5. Record the initial reading of the gas
meter(s);
6. Start the transfer of
gasoline to the storage tank(s) in accordance with facilities' established
normal procedures;
7. Record
temperature, pressure, and gas meter readings at two minute
intervals;
8. Record at the start
and the end of the test the barometric pressure and ambient
temperature;
9. Disconnect the tank
truck hoses from the storage tank in accordance with the procedures outlined by
the facility when the transfer has been completed;
10. Continue to record temperature, pressure,
and gas meter readings at the underground storage tank vent(s) at two-minute
intervals for a period of ten minutes after the completion of the gasoline
transfer;
11. Record the final
reading of the gas meter;
12.
Record the total volume of gasoline that was transferred; and
13. Disconnect the positive displacement
meter from the atmospheric vent.
(f) Calculate the efficiency of the vapor
recovery system using the following equation:
| E=1 - | V[v] (7.481) (T[s] + 460) (P[b]) | x
100 |
| ........................... |
| V[T] (T[v] + 460 (29.92) |
Where:
E=Percent efficiency of the vapor recovery system at standard
conditions.
V[v]=Volume of displaced vapors vented from the atmospheric
vent in actual cubic feet (ACF).
V[T]=Volume of gasoline transferred to storage tanks in
gallons.
T[v]=Temperature of vapors vented from atmospheric vent in
degrees Fahrenheit.
T[s]=Standard temperature (70 [degree]F).
P[b]=Average barometric pressure during test in inches of
mercury.
7.481=Conversion factor of gallons per cubic foot
(Gal/ft[LESS THAN]3[GREATER THAN]).
29.92=Standard pressure in inches of mercury.
(g) The test report shall include
the following information submitted on the required reporting forms listed in
Appendix H. (Any alternative report form shall be submitted to the Department
for review pursuant to
N.J.A.C.
7:27B-3.2(c) and (e)) :
1. A dimensioned sketch of the sampling
location detailing number of storage tanks, type of fill pipe; and type of
vapor recovery system;
2. The total
amount of each type of gasoline transferred;
3. The size of the storage tank(s) into which
the gasoline was transferred;
4.
The total amount of gasoline present in the storage tank(s) prior to
transfer;
5. Pressure/vacuum test
date listed on the tank truck; and
6. Identification of the tank truck.
