An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

Oklahoma SIP: OK 252:100-43 Part 3. Specific Methods, SIP effective 2000-01-03 to 2009-02-26

Regulatory Text:

252:100-43-15.  Gasoline vapor leak detection procedure by combustible gas detector

252:100-43-15.  Gasoline vapor leak detection procedure by combustible gas detector

(As approved by EPA 11/03/1999 (64 FR 59629) at 52.1920(c)(48) effective 01/03/2000.)

     (a) Principle.  A combustible gas detector is used to indicate any incidence of leakage from gasoline truck tanks and vapor control systems.  This qualitative monitoring procedure is an enforcement tool to confirm the continuing existence of leak-tight conditions.

     (b) Definitions.  The following words and terms, when used in this Section, shall have the following meaning, unless the context clearly indicates otherwise:
          (1)  "Truck tank" means any container, including associated pipes and fittings, that is used for the transport of gasoline.
          (2)  "Truck tank vapor collection equipment" means any piping, hoses, and devices on the truck tank used to collect and route the gasoline vapors in the tank to the bulk terminal, bulk plant, or service station vapor control system.
          (3)  "Vapor control system" means any piping, hoses, equipment, and devices at the bulk terminal, bulk plant, or service station, which is used to collect, store, and/or process gasoline vapors.

     (c)  Applicability.  The gasoline vapor leak detection procedure by combustible gas detector is applicable to determining the leak-tightness of gasoline truck tanks during loading without taking the truck tank out of service. The method is applicable only if the vapor control system does not create back-pressure in excess of the pressure limits of the truck tank compliance leak test.  For vapor control systems, this method is applicable to determining leak-tightness at any time.

     (d)  Apparatus and specifications.  
          (1)  Manometer.  Liquid manometer, or equivalent, capable of measuring up to 6250 pascals (25 inches H2O) gauge pressure with +25 pascals (0.1 inch H2O) precision shall be used.
          (2)  Combustible gas detector.  A portable hydrocarbon gas analyzer with associated sampling line and probe having the following specification shall be used.
               (A)  Safety.  The detector shall be certified as safe for operation in explosive atmospheres.
               (B)  Range.  The minimum range for the detector shall be 0-100 percent of the lower explosive limit (LEL) as propane.
               (C)  Probe diameter.  The sampling probe shall have an internal diameter of 0.625 cm (1/4 inch).
               (D)  Probe length.  The probe sampling line shall be of sufficient length for easy maneuverability during testing.
               (E)  Response time.  The response time for full-scale deflection shall be less than 8 seconds for detector with sampling line and probe attached.

     (e)  Test procedure.
          (1)  Pressure.  Place a pressure tap in the terminal, plant, or service station vapor control system, as close as possible to the connection with the truck tank.  Record the pressure periodically during testing.
          (2)  Calibration.  Calibrate the combustible gas detector with 2.2 percent propane by volume in air for 100 percent LEL response.
          (3)  Monitoring procedure.  During loading or unloading, check the periphery of all potential sources of leakage of the truck tank and of the terminal, plant, or service station vapor collection system with a combustible gas detector.
               (A)  Probe distance.  The probe inlet shall be 2.5 cm from the potential leak source.
               (B)  Probe movement.  Move the probe slowly (2.0 cm/second).  If there is any meter deflection at a potential leak source, move the probe to locate the point of highest meter response.
               (C)  Probe position.  As much as possible, the probe inlet shall be positioned in the path of (parallel to) the vapor flow from a leak.
               (D)  Wind.  Attempt as much as possible to block the wind from the area being monitored.
          (4)  Recording.  Record the highest detector reading and location for each incidence of leakage.