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Northwest Tank can help station owners comply with important Vapor Recovery Test requirements.

Vapor Recovery Test requirements vary based on the station location and fuel throughput. Permits obtained from the local clean air authority will further outline specific testing requirements for each site. Sites equipped with Stage II (Vacuum Assist or Balance) vapor recovery systems usually require testing. To determine the tests required for your site, Northwest Tank offers free consultations to assist station owners with compliance.

Tests conducted by Northwest Tank are completed in accordance with California Air Resource Board (CARB) executive orders and test procedures.

Static Pressure Decay Testing

Static Pressure Decay Testing is usually required annually for stations equipped with Stage II vapor recovery.

Requirements for Static Pressure Decay Testing:

  • Maximum 25,000 gallons of Ullage (vapor space) in the gasoline system. Diesel is not included.
  • Minimum of 1,000 gallons of Ullage in each tank.
  • Minimum 6 inches of fuel in each tank.
  • Minimum 3 hour period between fuel delivery and test.
  • Example:
    • Site equipped with (3) 10,000 gallon gas tanks (no diesel). This means the system capacity is 30,000 gallons.
    • Must have a minimum of 5,000 gallons in the entire system at the time of the test to meet the maximum requirement of 25,000 gallons of Ullage. The following combination would suffice (or any combination):
      • Regular 3,000 gallons
      • Midgrade 1,000 gallons
      • Premium 1,000 gallons
    • No more than 9,000 gallons of fuel in each tank
    • Each tank must have at least 6 inches of product to conduct the test
  • Typical down-time for test: The entire station must be shut down for 30 minutes prior to conducting this test. Test length is 5 minutes; however, typical testing time varies from 1-3 hours depending on troubleshooting requirements.

To read more about the California Environmental Protection Agency Air Resources Board Vapor Recovery Test Procedure (Static Pressure Decay) (TP-201.3) click here.

Air to Liquid Ratio Testing

Air to Liquid Ratio Testing applies only to sites equipped with Stage II Vacuum Assist vapor recovery systems.

Requirements for Air to Liquid Ratio Testing:

  • System must pass a Static Pressure Decay Test (see above).
  • Technician will dispense 2.5 – 10 gallons of product from each grade at each fueling point (excluding diesel). All products dispensed are returned to the storage tanks.
  • The test is conducted on one dispenser at a time.
  • Typical down-time for test: 1.5 - 3 hours. Stations can remain open for the duration of this test.

To read more about the California Environmental Protection Agency Air Resources Board Air to Liquid Volume Ratio Test Procedure (TP-201.5) click here.

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Dynamic Back Pressure

Dynamic Back Pressure Testing is conducted after installation or a retrofit of an existing system. Some Clean Air Agencies require this test on a regular basis (annually, bi-annually, etc.).

Requirements for Dynamic Back Pressure Testing:

  • System must pass a Static Pressure Decay Test (see above).
  • Typical down-time for test: The station must remain closed for this test. Total testing time varies from 0.5 - 2 hours.

To read more about the California Environmental Protection Agency Air Resources Board Air to Vapor Recovery Test Procedure (Dynamic Back Pressure) (TP-201.4) click here.

Stage I EVR Testing

All new construction Stage I systems require Stage I EVR configuration. Test requirements vary depending on requirements specified by the local clean air authority.

To view CARB Test Procedures for Stage I EVR click here.

Healy Stage II Testing

Stations equipped with Healy Stage II vapor recovery systems require specific testing equipment that is certified to test ORVR compatible systems. Northwest Tank’s team of skilled technicians are trained and fully equipped to conduct this test in accordance with CARB Executive Order G-70-191.


UST Compliance
Tank Tightness Testing
Line Tightness Testing
Leak Detector Testing
Cathodic Protection System
Tank Monitor Certifications
Helium Pinpoint Testing

Vapor Recovery
Static Pressure Decay Testing
Air-to-Liquid Ratio Testing
Dynamic Back Pressure
Stage I EVR Testing
Healy Stage II Testing

Meter Calibration
Meter Calibration Program

Compliance Test Center
Web Access Testing Results


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