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GB 20952-2007 PDF in English


GB 20952-2007 (GB20952-2007) PDF English
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GB 20952-2007: PDF in English

GB 20952-2007
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 13.040.40
Z 60
Emission standard of air pollutant for gasoline filling
stations
ISSUED ON: JUNE 22, 2007
IMPLEMENTED ON: AUGUST 01, 2007
Issued by: State Environmental Protection Administration;
General Administration of Quality Supervision, Inspection and
Quarantine.
Table of Contents
Foreword ... 4 
1 Scope ... 5 
2 Normative references ... 5 
3 Terms and definitions ... 5 
4 Gasoline vapor emission control and limit ... 7 
5 Technical measures ... 11 
6 Standard implementations ... 13 
Annex A (normative) Testing methods for liquid resistance ... 15 
Annex B (normative) Testing methods for vapor recovery system tightness .. 19 
Annex C (normative) Testing methods for air to liquid volume ratio ... 24 
Annex D (normative) Testing methods for vapor emission processing equipment
... 33 
Annex E (informative) Calibration method for on-line monitoring system ... 36 
Annex F (informative) Testing report of gasoline filling station ... 39 
Emission standard of air pollutant for gasoline filling
stations
1 Scope
This Standard specifies gasoline vapor emission limits of gasoline filling
stations, control technical requirements and testing methods.
This Standard is applicable to gasoline vapor emission management of existing
gasoline filling stations as well as environmental impact assessment, design,
completion acceptance of new, modified and expanded gasoline filling station
projects and gasoline vapor emission management after completion.
2 Normative references
The provisions in the following documents become part of this Standard,
through reference in this Standard. For undated documents, the latest version
applies to this Standard.
GB 50156, Code for design and construction of automobile gasoline and gas
filling station
GB/T 16157 The determination of particulates and sampling methods of
gaseous pollutants emitted from exhaust gas of stationary source
HJ/T 38 Stationary source emission - Determination of nonmethane
hydrocarbons - Gas chromatography
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 gasoline filling station
A special place for filling gasoline into car fuel tank.
3.2 gasoline vapor
Volatile organic compounds (non-methane total hydrocarbons) generated
during the filling, unloading and storage of gasoline at gasoline filling stations.
3.3 vapor emission concentration
Under standard conditions (temperature is 273K, pressure is 101.3kPa), the
mass of non-methane total hydrocarbons contained in every m3 of dry gas
discharged, in g/m3.
3.4 vapor recovery system for gasoline filling station
A vapor recovery system for gasoline filling station is composed of vapor
recovery system for unloading, closed storage of gasoline, vapor recovery
system for filling, online monitoring system, and vapor emission processing
equipment. The role of this system is to TRANSFER the gasoline vapor
generated during the unloading, storage and filling of the gasoline filling station,
through closed collection, storage and sending into the tank of a tank car, and
TRANSPORT to the oil storage depot for centralized recovery into gasoline.
3.5 vapor recovery system for unloading gasoline
A system that collects the gasoline vapor generated when a tank car unloads
gasoline, through a closed manner, into the tank of the tank car.
3.6 vapor recovery system for filling gasoline
A system that collects the gasoline vapor generated when a tank car fills
gasoline, through a closed manner, into the underground storage tank.
3.7 overfill protection measurement
The overfill that might happen when controlling gasoline unloading by using
shut-off valve or float valve or other anti-overflow measures.
3.8 underground storage tank
A fully-buried storage tank under the ground.
3.9 pressure/vacuum valve
Also known as P/V valve, vent valve, mechanical breathing valve, which can
adjust the pressure difference between the inside and outside of the tank so
that the gas inside and outside the tank can communicate.
3.10 dynamic back pressure
The resistance when condensate liquid stays in the gasoline vapor pipeline or
causes gas to pass through the pipeline for other reasons.
3.11 vapor recovery system tightness
The sealing degree of vapor recovery system under certain gas pressure.
3.12 air to liquid volume ratio
The ratio of the volume of gasoline vapor collected when filling to the volume of
gasoline added to the tank at the same time.
3.13 vacuum-assist
In the vapor recovery system for filling gasoline, use the vacuum generator to
assistant recovering the gasoline vapor generated during gasoline filling.
3.14 on-line monitoring system
The system that online monitors whether the air to liquid volume ratio in the
vapor recovery process for filling gasoline as well as the vapor recovery system
tightness of the vapor recovery system and pipeline liquid resistance are normal.
When abnormality is found, it can remind the operator to take corresponding
measures, and can record, store, process and transmit monitoring data.
3.15 vapor emission processing equipment
The device that recovers the gasoline vapor discharged from the vapor
recovery system for gasoline filling station, through methods such as attaching,
absorption, condensation, membrane separation.
4 Gasoline vapor emission control and limit
4.1 The gasoline vapor emitted during unloading, storing and filling of gasoline
filling station shall use the gasoline vapor recovery method based on closed
collection to control.
4.2 Technical assessment
4.2.1 The vapor recovery system for filling gasoline shall conduct technical
assessment and issue a report. The assessment mainly includes: investigating
and analyzing technical information, verifying relevant certification documents,
evaluating air to liquid volume ratio of multiple flows and guns, testing
operations of at least 3 months in concession, providing rang of air to liquid
volume ratio of which the control efficiency is greater than or equal to 90%,
listing equipment of vapor recovery system.
4.2.2 The vapor emission processing equipment (hereinafter referred to as the
processing equipment) and on-line monitoring system shall conduct technical
assessment and issue a report. The assessment mainly includes: investigating
and analyzing technical information, verifying relevant certification documents,
providing proof of actual use in China or abroad, testing operations of at least
3 months in concession.
5 Technical measures
5.1 Emission control of gasoline vapor of unloading gasoline
5.1.1 It shall use submersible unloading method. The height of the gasoline
outlet of the unloading pipe from the bottom of the tank shall be less than
200mm.
5.1.2 The gasoline unloading and oil recovery interface shall be installed with
DN100mm shut-off valve, sealed quick connector and cap. For the exiting
gasoline filling stations, if unloading emission control measures have been
taken but the interface size does not match, it may use a reducing diameter one
to connect.
5.1.3 The connecting hose shall be connected to the unloading truck with a
DN100mm sealed quick connector. No residual oil can be left in the connecting
hose after unloading.
5.1.4 All gasoline vapor pipeline emission ports shall be equipped with
pressure/vacuum valves according to the requirements of GB 50156.
5.1.5 The underground pipeline connected to the exhaust pipe shall slope to
the oil tank. The slope shall not be less than 1%. The pipeline diameter is not
less than DN50mm.
5.1.6 For gasoline filling stations that have not taken technical measures for
filling and storage of gasoline vapor recovery, when unloading, the gasoline
measuring hole and other parts that may cause gas short circuit shall be sealed,
so as to ensure that the gasoline vapor generated by unloading gasoline is
sealed and replaced in the tank of tank car.
5.2 Gasoline vapor emission control of gasoline storage
5.2.1 All components that affect the tightness of gasoline vapor stored, including
gasoline vapor pipelines and connected flanges, valves, quick couplings, and
other related components shall be guaranteed to be free of air leakage when
less than 750Pa.
5.2.2 The underground storage tank shall use electronic liquid level gauge to
measure the tightness of gasoline. The electronic liquid level measurement
system with leak detection function shall be selected.
5.2.3 It shall adopt overfill protection measurements that meet relevant
requirements.
5.3 Emission control of vapor recovery for filling gasoline
Annex A
(normative)
Testing methods for liquid resistance
A.1 Application scope
This appendix is applicable to the liquid resistance testing of the underground
vapor recovery pipeline from the gasoline dispenser to underground storage
tank. It shall test the liquid resistance of the underground vapor recovery
pipeline from each gasoline dispenser to underground storage tank.
Special attention: the regulations on safety production of gasoline filling stations shall be
strictly implemented during testing.
A.2 Testing principle and overview
A.2.1 Fill the vapor recovery pipeline with nitrogen at the specified nitrogen flow.
Simulate gasoline vapor through gasoline vapor recovery pipelines.
A.2.2 Use a pressure gauge or equivalent device to detect the liquid resistance
of the gas through the pipeline. Know the degree of resistance to gas in the
pipeline due to various reasons and use to judge whether it shall affect the
vapor recovery.
A.3 Deviation and interference
A.3.1 Any leaks in the relevant vapor pipelines shall result in low fluid resistance
measurement.
A.3.2 If it starts testing when nitrogen flow stabilizes less than 30s, it shall
produce erroneous liquid resistance measurement.
A.4 Testing equipment
A.4.1 Nitrogen and nitrogen bottles. Uses commercial grade nitrogen, high-
pressure nitrogen cylinder with two-level pressure regulator and a 6.9kPa relief
valve.
A.4.2 Pressure gauge. Use the pressure gauge described in A.5.1, A.5.2 and
A.5.3.
A.4.3 Float flowmeter. Use the float flowmeter described in A.5.4. It and the
pressure gauge shall form the testing equipment for liquid resistance (see
Figure A.1).
A.6 Testing procedures
A.6.1 Open the bottom pot of the gasoline dispenser being tested. Find the
three-way and testing joints reserved on the vapor recovery riser pipe for filling
gasoline.
A.6.2 Connect the liquid resistance testing device to the three-way testing
connector through a hose.
A.6.3 Ground the nitrogen bottle. Connect the nitrogen pipe to the nitrogen inlet
connector of the liquid resistance testing device.
A.6.4 Open the vapor interface valve of vapor recovery system for unloading
gasoline of corresponding tank.
A.6.5 If testing new, modified and expanded gasoline filling stations, 10L
gasoline shall be injected into the pipeline before soil coverage on vapor
pipelines and ground hardening construction.
A.6.6 Turn on the nitrogen bottle. Set the pressure of the low-pressure regulator
to 35kPa. Use a float flow control valve to regulate the nitrogen flow. Starting
with the lowest nitrogen flow in Table 1, respectively test the liquid resistance
corresponding to 3 flows. Before reading the pressure gauge value, the nitrogen
flow shall be stable for more than 30s.
A.6.7 If any one of the three liquid-resistance tested values is greater than the
maximum pressure limit specified in Table 1, the liquid resistance of the
gasoline filling station shall be nonconforming. If the test value cannot be
determined due to the jitter of the pressure gauge, the liquid resistance test is
deemed nonconforming.
A.6.8 Remove the hose connected to the three-way testing connector. Restore
the connection of the original vapor recovery pipeline.
A.6.9 Close the vapor interface valve of the corresponding tank.
A.7 Testing record
See Table F.1 in Annex F for liquid resistance testing result record of vapor
recovery pipelines.
which shall affect the vapor recovery system tightness testing of the entire
system, it shall set up a short-circuit pipeline with a shut-off valve.
B.4 Testing equipment
B.4.1 Nitrogen and nitrogen bottle, same with A.4.1.
B.4.2 Pressure gauge. Use the pressure gauge described in B.5.1 and B.5.2.
B.4.3 Float flowmeter. Same with A.4.3. It and the pressure gauge shall form
the testing device for vapor recovery system tightness (see Figure A.1).
B.4.4 Stopwatch. Same with A.4.4.
B.4.5 Three-way testing connector. Same with A.4.5.
B.4.6 Hose. Same with A.4.6.
B.4.7 Grounding device. Same with A.4.7.
B.4.8 Leak detection solution. Any solution that can be used to detect gas leaks,
used to inspect the vapor recovery system tightness of system components.
B.5 Sensitivity, range and accuracy
B.5.1 The minimum diameter of mechanical pressure gauge dial is 100mm. The
measuring range is 0~750Pa. The accuracy is 2% of full measuring range. The
minimum scale is 25Pa.
B.5.2 When the full measuring range of electronic pressure measuring device
is 0~2.5kPa, the accuracy is 0.5% of full measuring range. When the full
measuring range is 0~5.0kPa, the accuracy is 0.25% of full measuring range.
B.5.3 The minimum vapor space of a single oil tank shall be 3800L or 25% of
the volume of the oil tank. Take the smaller value of the two. The maximum total
vapor space to connect the oil tank shall not exceed 95000L. The above does
not include the volume of all vapor pipelines.
B.5.4 The flow rate of filled nitrogen is 30~100L/min.
B.5.5 Float flowmeter is the same as A.5.4.
B.5.6 Stopwatch same as A.5.5.
B.5.7 All measuring instruments shall be calibrated according to measuring
standards.
B.6 Procedures before testing
calibration point. The calibration frequency shall not exceed 90d.
B.6.8 Use formula B.1 to calculate the time required to pressurize the system
to 500Pa.
B.6.9 Use a hose to connect the testing device of vapor recovery system
tightness and the nitrogen bottle, three-way testing connector. Open the cut-off
valve on the short circuit. Read the initial pressure of oil tank and underground
pipeline. If the initial pressure is greater than 125Pa, release the pressure to
make the pressure of the oil tank and underground pipeline less than 125Pa.
B.6.10 Any electronic pressure gauge shall be preheated and drift checked
before use (see B.3.4).
B.7 Testing procedures
B.7.1 Pressurize the vapor recovery system (or independent sub-system).
Open the nitrogen cylinder valve. Set the pressure of the low-pressure regulator
to 35kPa. Adjust the nitrogen flow rate in the range of 30~100L/min. Start the
stopwatch. Pressurize to about 550Pa. During the pressurizing process, if the
time required to reach 500Pa has exceeded 2 times the calculated value of
formula B.1, then stop testing and indicate that the system does not have the
testing conditions.
B.7.2 Close the nitrogen valve when charging to about 550Pa. Adjust the
pressure relief valve to reduce the pressure to 500Pa and start the stopwatch.
B.7.3 Record the system pressure every 1min. After 5min, record the final
system pressure.
B.7.4 Release the pressure of the vapor recovery system according to the
safety regulations of the gasoline filling station.
B.7.5 Remove the hose connected to the three-way testing connector. Restore
the connection of the original vapor recovery pipeline.
B.7.6 If the vapor recovery system consists of several independent vapor
recovery subsystems, then each independent subsystem shall be tested for
vapor recovery system tightness.
B.8 Procedures after testing
Compare the system pressure testing value after 5min with the minimum
residual pressure limit in Table 2 to determine if the gasoline filling station
complies with the standard. If the actual vapor space value is between the two
vapor space values listed in Table 2, then use the interpolation formula B.2 to
calculate the minimum residual pressure limit.
Annex C
(normative)
Testing methods for air to liquid volume ratio
C.1 Application scope
This appendix is applicable to the air to liquid volume ratio testing of vapor
recovery system for gasoline filling station.
Special attention: the regulations on safety production of gasoline filling stations shall be
strictly implemented during testing.
C.2 Testing principle and overview
Install a tight adapter at the nozzle of the refueling gun. The adapter is
connected to the gas flow meter. The air flow first passes through the gas flow
meter, and then enters the vapor collection hole on the nozzle of the refueling
gun. The ratio of the measured gas volume to the gasoline volume measured
simultaneously by the gasoline dispenser is called the air to liquid volume ratio.
Through the testing of the air to liquid volume ratio, the recovery effect of the
vapor recovery system can be known.
C.3 Deviations and interference
C.3.1 If the nozzle of the refueling gun and the adapter cannot be matched well
for various reasons, the test cannot be performed.
C.3.2 If the filling flow rate of the tested refueling gun cannot reach more than
20L/min, the test cannot be performed.
C.3.3 If other refueling guns that share a vacuum pump with the refueling gun
being tested are sealed, the test results shall be deviated.
C.3.4 If the tested refueling gun brings gasoline into the testing device, the air
to liquid volume ratio test value of the refueling gun shall be considered invalid.
C.3.5 Before testing, do not empty the gasoline in the gas line of the refueling
hose and the vapor pipe of the refueling machine, otherwise the test results
shall be deviated.
C.3.6 Before the air to liquid volume ratio test, the O-ring of the air to liquid
volume ratio adapter shall be properly lubricated, otherwise the test results shall
be deviated.
C.7.8 If the air to liquid volume ratio calculated according to formula C.1 is within
the standard limits, the air to liquid volume ratio of the tested refueling gun is
up to the standard.
C.7.9 If the air to liquid volume ratio is not within the standard limits, and the
difference between the air to liquid volume ratio detection value and the limit is
less than or equal to 0.1, two more air to liquid volume ratio tests shall be
performed. But do not make any adjustments to the filling pipeline or the vapor
recovery pipeline. In order to ensure the accuracy of the measurement, the
necessary adjustments to the gas-liquid ratio detection device are allowed,
including the air to liquid volume ratio adapter and the refueling gun. If the air
to liquid volume ratio testing device is adjusted, the previous test result of this
gun shall be invalid. Take the arithmetic average of 3 test results. If the average
value of the air to liquid volume ratio is within the given limits, the air to liquid
volume ratio of the refueling gun is up to the standard. If the average value is
outside the limit range, it means that the air to liquid volume ratio test of the
refueling gun is not up to the standard.
C.7.10 If the air to liquid volume ratio is not within the specified limit range, and
the difference between the tested value of the air to liquid volume ratio and the
limit value is greater than 0.1, the air to liquid volume ratio test of the tested
refueling point does not meet the standard.
C.7.11 In order to avoid the accumulation of gasoline, after each test, drain the
condensed gasoline in the hose between the gas flowmeter and the oil barrel
component for testing and the hose between the air to liquid volume ratio
adapter and the gas flowmeter.
C.8 Procedures after testing
C.8.1 Remove the air to liquid volume ratio adapter from the refueling gun.
C.8.2 Carefully pour the filled gasoline back to the corresponding gasoline
storage tank Keep the testing barrel grounded before pouring gasoline. Without
the consent of the owner of the gasoline filling station, do not mix different
grades of gasoline in the oil barrel. If different grades of gasoline are mixed in
the oil barrel, the mixed gasoline shall be poured back to the lower grade oil
storage tank.
C.8.3 Before finally determining whether the air to liquid volume ratio test meets
the standard, perform a leak check on the adapter according to C.6.6. If the
testing device fails the leak check, all data obtained during the air to liquid
volume ratio test shall be invalid.
C.8.4 Before transportation, carefully seal the inlet and outlet of the gas
flowmeter to prevent foreign matter from entering the flowmeter.
1.1m high guardrail. The sampling hole is 1.2~1.3m above the platform. If the
sampling position is less than 1.5m above ground level, the monitoring
operation platform and guardrail may not be set.
D.2.5 The installation of the sampling hole and operation platform shall be
completed and accepted at the same time as the vapor recovery and treatment
project.
D.3 Testing method
D.3.1 The testing of the emission concentration of the processing equipment
shall be carried out during the period when the ambient temperature is not lower
than 20°C and when the filling is relatively concentrated.
D.3.2 Each processing equipment shall be tested. The sampling time of each
processing equipment is not less than 30min. It can conduct continuous
sampling or equal time interval sampling. The number of samples collected at
equal intervals is not less than 3.
D.3.3 Other sampling requirements shall be implemented according to GB/T
16157.
D.3.4 The analysis method is implemented according to HJ/T 38.
D.4 Testing equipment
D.4.1 Sampling joint. There shall be a universal sampling joint connected to the
outlet sampling hole of the processing equipment. The connection method of
the sampling joint and the sampling hole can be designed according to different
sampling methods. However, the length of the sampling tube placed in the
sampling hole tube on the sampling joint shall not be less than 56mm. The
distance that the sample enters the collector through the sampling tube and
other components shall not exceed 300mm. The inner diameter of the sampling
tube is 5mm.
D.4.2 For sampling with a syringe, refer to the sampling joint below. The
sampling joint is a flange cover. The size is consistent with the sampling hole
flange. At the center position of the flange cover, seal and weld a section of
sampling tube through the flange cover. The length of the sampling tube
inserted into the sampling hole tube is 56mm. The length of the other side is
20mm, and the inner diameter of the sampling tube is 5mm.
D.4.3 Sampling joint material. Sampling joint shall use copper, aluminum or
other materials that do not generate sparks and static electricity.
D.5 Testing record
Refer to Table F.4 in Annex F for the record of vapor emission test results of
Annex E
(informative)
Calibration method for on-line monitoring system
E.1 Application scope
This appendix is applicable to the calibration of the on-line monitoring system
of vapor recovery system for gasoline filling station.
E.2 Principle and overview of on-line monitoring system
E.2.1 A gas flowmeter is connected in series on the vapor recovery pipeline in
the gasoline dispenser. By measuring the recovered vapor volume and
comparing with the volume of liquid gasoline corresponding to the vapor volume,
monitor the air to liquid volume ratio during vapor recovery process.
E.2.2 Install a pressure sensor on the vapor recovery pipeline in the connected
vapor storage space. By measuring the change of pressure value, monitor the
vapor recovery system tightness.
E.2.3 The data collected by the flowmeter and pressure sensor is sent to the
data processing system. When the vapor recovery system is in an abnormal
working state, the monitoring system shall issue a warning. If no processing
measures are taken within the warning period, the system shall alarm and take
measures to stop filling gasoline.
E.3 Pressure sensor calibration test procedures
Step 1: Record the serial number of the gasoline dispenser and installed
pressure sensor.
Step 2: Remove the cap from the pressure sensor environmental reference port
valve. Rotate the valve 90° to open it. Make the valve accessed with air.
Step 3: Open the diagnostic mode menu on the front panel of the console. Enter
the smart sensor calibration menu. Record the pressure value.
Step 4: Observe whether the pressure value is within ± 50Pa. If the pressure
valve is not within this range, leave the valve position as described in
step 2. Replace the sensor according to the pressure sensor installation
guide. Then repeat the test according to step 3 to meet the pressure
range.
Step 5: Cover the cap of the pressure sensor environmental reference port
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.