‘Unintended Activation Releases the Entire Contents of a CNG Cylinder’
NGVAmerica’s Clean Vehicle Education Foundation affiliate has issued a safety alert about the use of European-style 200-bar/3,000-psi-rated “rupture disc style” pressure relief devices on the 250-bar/3,600-psi compressed natural gas cylinders prevalent in the U.S. and Canada. The PRDs in question are marked in accordance with the European requirements for vehicles with 200 bar service pressure, notes the Alert.
CVEG cites reports of unintended activation of the PRDs, and says the reports “are alarming because unintended activations had not been reported since development and first adoption of ANSI PRD1 in 1998.
“An unintended activation releases the entire contents of a CNG cylinder within a minute or two with far more severe potential consequences than a smaller leak.
‘High Risk of a Serious Fire’
“Had these vehicles been inside a building at the time of the unintended release,” states the Alert, “a large cloud of natural gas would have formed with high risk of a serious fire.”
European or global CNG components that are not designed and marked for the higher service pressure of 3,600-psi used in the U.S. “should not be used here,” CVEF says, noting that it has received word that some distributors in the U.S. have sold – “and are still selling” – the underrated components.
￼The Alert includes further information on ANSI PRD1 and the newer NGV3.1 standards, and recommendations on dealing with the Euro-PRD issue.
CVEF, president Doug Horne, 770-424-8575; [email protected]
CVEF, John Dimmick, [email protected]; www.cleanvehicle.org (direct link to CVEF Safety Alert, PDF format)
Source: NGVAmerica/CVEF with Fleets & Fuels follow-up