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2.10 Balance Vapor Recovery System Installation Requirements
2.10.1 Dynamic Back Pressure Testing
At initial installation, balance vapor recovery dispensers should have a dynamic back pressure test
performed at each nozzle to ensure there are no blockages in the vapor recovery system.
The dispenser should be connected to the underground and the hanging hardware (hoses, nozzles,
breakaways, etc.) should be installed.
The following test methods or equivalent methods can be used:
"ST-27 Gasoline Dispenser Facility Back Pressure." Available from the California Bay Air
Management District via the Internet at http://www.baaqmd.gov/mop/vol4/v4index.htm
"TP201.4" Determination of Dynamic Pressure Performance of Vapor Recovery Systems of
Dispensing Facilities." Available from the California Air Resources Board.
Maximum allowable dynamic back pressure for an individual dispenser nozzle using either test pro-
cedure is listed below:
60 cu. ft. per hr. < 0.35 in. of water
80 cu. ft. per hr. < 0.62 in. of water
Note: Very low numbers for back pressure results may indicate a leak in the system and it should
be checked.
2.10.2 Back Pressure System Check List
Note: Check test equipment for up-to-date calibration stickers. Normal use of rotameters and
pressure gauges necessitates yearly calibration; calibration is also required if this equipment has
been dropped or mishandled.
1. Check test equipment for leaks prior to use. Pressurize with nitrogen supply (plug nozzle end of
the fill pipe). Adjust nitrogen until 50% on pressure gauge is reached. Close off supply. A pres-
sure decay must not be more than 0.2 in. of water in five minutes.
2. If facility has a vapor pod (condensate pot), drain prior to testing.
3. Open dry break poppets.
4. Completely drain hoses and nozzles prior to test. A pulsating needle indicates fluid in the lines.
Re-drain if necessary.
5. The following information should be included on the field data sheet:
• Facility address and ID
• Pump number and grade ID
• Nozzle make and model
• Back pressure in inches of water
• Nitrogen flow rate
16
Part No. 920559 Rev H
November 2008
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