Review of four international LNG standards (ISO 12991-2012, NFPA 52-2013, SAE J2343-2008 and AS 2739-2009) for requirements related to LNG tank shut-off devices. The report discusses specific aspects and challenges of mounting two valves in series on same LNG line. The emphasis is on using two components, a manual valve and an automatic valve mounted in series on
the LNG supply line to shutoff the flow.
Mihai Ursan (Westport) prepared a document (LNG TF-11-02) that included international LNG codes. The ISO standard 12991 comes close to what we were attempting to achieve in the language, Also reviewed was NFPA 52 and Australia/New Zealand AS/NZS 2739-2009. All the standards Mr. Ursan researched require the isolation/shut off of the fuel. Each of the standards referenced uses different wording but the shutoff of the fuel line is required. None of the standards referenced require two valves for the shutoff.
Mr. Ursan explained that the automatic valve is safer than only a manual valve. If only a manual valve is used it exposes any person who may respond to an (emergency) incident to a dangerous situation by reaching for a manual shut off valve. Manual valves also are subject to human error if someone turns it off and doesn’t remember to turn it on again when the vehicle is ready to be driven. It is easy to misuse the manual valve by closing it and forgetting to turn it on again, which is something that Westport has experienced with some of their customers. Westport left only an automatic valve on their customers’ tanks and removed the manual valve.