CSA/ANSI NGV 4.1-2018 Natural gas vehicle (NGV) dispensing systems.
5 Construction
5.1 Housing
The construction of the housing, where provided, shall be such that it will not become warped, bent, loosened, or otherwise damaged In normal operation so as to prevent the device from complying with these requirements. A recess or depression in the housing that may collect water shall contain means to drain the water to an area that will not cause an unsafe condition.
The construction of housings not specifically covered by this Standard or Clause shall be in accordance with reasonable concepts of safety, substantiality, and durability. All specifications as to construction set forth herein may be satisfied by the construction actually prescribed or such construction as will provide at least equivalent performance.
The housing shall afford space for making field connections of gas-carrying piping and electrical equipment. Openings with acceptable closures shall be provided for making connections and for inspection and adjustment of the operating mechanism after installation. Closures shall require a key or tool to open.
Housings, which enclose gas carrying components, shall incorporate vent opening(s) near the top, totaling an area of not less than 8 cm2 (1-1/4 in2) to prevent the accumulation of gas. These openings shall be of such size and arrangement as to avoid clogging and water penetration.
A plastic panel used as part of the housing shall remain intact when subjected to room temperature and cold impact tests as described in Clause 6.4. Except as otherwise stated, testing at room temperature will be conducted between 15 °C (59F) minimum, and 30 °C (86°F) maximum.
Plastic parts shall be resistant to deterioration from conditions imposed on them in service.
5.2 Pressure relief valves
Pressure relief valves shall comply with and be sized in accordance with API Standard 520; and installed
in accordance with Section VIII, Division 1 of the ASME Boiler and Pressure Vessel Code, CSA B51, or CGA
A pressure relief valve shall be located downstream of the overfill protection system to prevent over-
pressurization of the vehicle storage vessels (see Clause 5.9). PRV settings are to be consistent with
CSA/ANSI NGV 1, CSA B51, Part 2, CSA B 108, or NFPA 52.
The discharge opening of all pressure relief valves shall be vented to a safe location, as allowed in
ANSI/NFPA 52, and CSA B108.
5.3 Filters
If a gas line filter is included as part of the dispenser, it shall be installed at a point upstream of all gas controls. The filter shall be of adequate size and constructed for the application, and shall be accessible for inspection, cleaning, and replacement, without taking apart the gas handling lines or disturbing any part of the dispensing device assembly (for WARNING see Clause 7.2).
The filter shall be installed in such a manner so that the force required to install or open the filter will not permanently distort the piping or other components of the dispenser.
5.4 Valves
Valves certified by a nationally recognized testing agency as complying with an approved standard shall be considered as complying with this Clause.CSA/ANSI NGV 4.1 pdf download.