Vapour control systems in gasoline distribution networks

1. SCOPE

This National Standard of Canada defines equipment requirements, performance criteria, and operating and testing procedures for the implementation of a vapour control system (VCS) in gasoline distribution

networks including terminals, bulk plants, service stations and cargo tanks, commonly known as Stage I.

( See Figure 1 for a schematic representation).

This standard does not include vapour control systems for vehicle refuelling commonly known as Stage II, rail car, marine transfers or aviation gasoline facilities.

This standard has been developed to provide regulators, users, installers and compliance authorities with a uniform installation reference for Stage I vapour control systems.

Extent of coverage — This standard provides performance criteria for equipment in use and specifies the type of interconnecting fittings to be used at terminals, bulk plants and service stations, and on cargo tanks. This standard

does not provide design specifications for individual components such as mechanical design of a fitting or detailed

piping layout.

This standard also includes procedures for operating the Stage I VCS facilities in the various locations.

Simplified schematics have been provided to illustrate possible field installations and checks.

The test procedures included in this standard provide the basis for assessing the compliance of the equipment and systems with the requirements of the authority having jurisdiction.

Application of this standard — The user of this standard shall refer to the authority having jurisdiction in the application of this standard.

Certain considerations are required in the application of this standard.

The maximum back-pressure at the cargo tank to provide sufficient head to drive the vapour recovery unit (VRU) is specified as a maximum 4.5 kPa (18 in. of water).

There is a concern with the flow characteristics of poppetted vapour connections. Poppetted adaptors with low restriction to flow may be necessary for some applications and are recommended for vapour connections to cargo

tanks.

For equipment and safety protection, the use of pressure/vacuum (PV) vents on underground tanks is not recommended as such devices do not improve vapour recovery.

Flame arrestors conforming to U.S. Underwriters Laboratories Inc. (UL1) standards and documents are recommended in vapour recovery lines for the fire protection of VRU systems. Flame arrestors shall be sized so as not to increase system back-pressures beyond the levels specified in maximum back-pressure stated above.

Present test methods, outlined in 7, are based on U.S. Environmental Protection Agency (EPA) test methods and data gathered from a large-scale pilot program operated in the Greater Vancouver Regional District (GVRD) in

1989/1990.

Gasoline–alcohol blends — The owner/operator of distribution networks handling gasoline–alcohol blends shall ensure that the materials and processes of the vapour recovery facility are compatible with such blends.

Quantities and dimensions in this standard are given in SI units with imperial equivalents, mostly obtained through soft conversion, given in parentheses. The SI units shall be regarded as official in the event of dispute or unforeseen difficulty arising from the conversion.

The testing and evaluation of a product against this standard may require the use of materials and equipment that could be hazardous. This standard does not purport to address all the safety aspects associated with its use. Anyone using this standard has the responsibility to consult the appropriate authorities and to establish appropriate health and safety practices in conjunction with any applicable regulatory requirements prior to its use.