‘Temperature Compensation Is Critical to CNG Vehicle Safety:’
CVEF Issues Technical Bulletin on Temperature Compensation
The Clean Vehicle Education Foundation and NGVAmerica are warning compressed natural gas providers and operators to make sure their equipment is properly calibrated for winter temperatures.
Simply put, natural gas vehicles may be over-filled in extremely cold temperatures, leading to a hazard if the weather warms or the vehicle is parked indoors.
CVEF has issued Reliable Temperature Compensation Is Critical to CNG Vehicle Safety, a technical bulletin that addresses the potential hazards created by the failure of CNG dispensers to accurately compensate for temperature.
‘Proper Temperature Compensation Is Essential’
“Proper temperature compensation is essential to safely fuel CNG vehicles, regardless of station type,” CVEF says, “as serious incidents have resulted from the overfilling of CNG containers at both fast-fill and time-fill facilities.”
The bulletin recommends
- that CNG station operators get in touch their fast- and time-fill dispenser suppliers to make sure they have – and are using – the latest set of written instructions and maintenance schedules as required in NFPA 52-2013;
- that station operators schedule annual temperature and pressure calibrations and function checks in early fall to allow time for any needed corrective action before winter temperatures; and
- that station operators ask their dispenser suppliers whether existing dispensers comply with the requirements of NFPA 52-2013.
“Limiting the maximum pressure in the cylinder is not as simple as limiting the pressure dispensed to the vehicle,” CVEF says. “The temperature of the gas in a CNG container may increase after fueling if the temperature of the environment increases before the fuel is used.
“This may occur with warming outdoor temperatures or when parking indoors… This issue is especially important to address prior to the cold temperatures many parts of the country experience during winter months.”
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Source: CVEF/NGVAmerica with Fleets & Fuels follow-up
They work fine in the winter but extra care should be taken when fueling.