Vapour control systems in gasoline distribution networks

Note: The scope for this NOI (originally published on November 22, 2022) was updated by the responsible SDO on December 19, 2023.

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 controls (see Figure 1 for a schematic representation).

This standard does not address vapour control systems for vehicle refuelling, 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 controls.

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 facilities at 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 — This standard does not preclude or override any applicable regulatory requirement where such regulations establish more restrictive limits than those given in this standard.

Certain considerations are required in the application of this standard.

The specified maximum back-pressure at the cargo tank is 4.5 kPa (18 in. of water) to ensure proper operation of the vapour control system.

There is a concern with the flow characteristics of poppetted vapour connections. Poppetted adaptors with low restriction to flow can 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 can freeze in the winter and therefore not improve vapour recovery during the filling of storage tanks.

Flame arrestors conforming to U.S. Underwriters Laboratories Inc. (UL^[1]) standards and documents are recommended in vapour recovery lines for the fire protection of vapour recovery unit (VRU) systems. It is necessary that flame arrestors be sized so as not to increase system back-pressures beyond the maximum back-pressure specified above (see 5.1.1.5, 5.2.1 and 5.3.1).

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 that operated in the Greater Vancouver Regional District (GVRD) in 1989-1990.

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

Units of measure ─ 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 are regarded as being official in the event of dispute or unforeseen difficulty arising from the conversion. This standard expresses the industry standard nominal unit of measurement in North America of “% by volume”, “ppm by volume”, “m³” and “mg/ m³”. The SI equivalent expression for these unit are % (V/V), ), mL/m³, litre and mg/L respectively.

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.

[1] The required information may be obtained by contacting the Underwriters Laboratories Inc. Telephone: 847-272-8800. Web site: www.ul.com.