Certain pressure relief valves for use on compressed natural gas fuel tanks are being recalled by Circor, which does business as Circle Seal Controls.

The affected valves have O-rings that could fail after being exposed to cold temperatures, allowing natural gas to leak from the fuel tank, which could increase the risk of a fire or explosion, according to a National Highway Traffic Safety Administration bulletin. More than 67,000 valves are part of this recall.

The valve model numbers are: 8100-11-T1T1, 8100-37-BB, 8100-44-BB, 8100-77-BB, 8100-84-BB, 8100-94-BB, and 8100-97-BB. All were manufactured July 2011 through December 2013.

Circle Seal will notify the CNG tank manufacturers of the defect. Vehicle owners will likely be notified by either their vehicle manufacturer or by the supplier of the CNG kit, according to NHTSA.

Owners of dual-fuel vehicles, such as those that may operate on CNG or petroleum, will have the affected valves replaced free of charge.

Owners of vehicles that operate only on CNG and were originally sold in, or are currently registered in, the states of Alaska, Colorado, Connecticut, Idaho, Iowa, Illinois, Indiana, Massachusetts, Maine, Michigan, Minnesota, Montana, Nebraska, New Hampshire, New York, New Jersey, North Dakota, Ohio, Pennsylvania, Rhode Island, South Dakota, Utah, Vermont, Wisconsin, and Wyoming will also have their affected valves replaced.

Replacement valves are expected to be available in the fall of 2014. Interim notifications will be sent this month or in June, 2014. A second notification will be sent when parts are available.

Owners may contact Circor at 1-951-270-6231 or the National Highway Traffic Safety Administration Vehicle Safety Hotline at 1-888-327-4236.