Wednesday, April 26, 2006

MedWatch Warning: Risk of Oxygen Regulator Fires from Poor Gasket Use

April 25, 2006 — Healthcare professionals and the public have been warned by The US Food and Drug Administration (FDA) and the National Institute for Occupational Safety and Health (NIOSH) of the risk for fires from the cylinder valves and regulators of oxygen tanks.

MedWatch, the FDA's safety information and adverse event reporting program reports today that fires have been linked to the incorrect use of CGA 870 seals.

The FDA has received 12 reports in which the regulators burned or exploded, in some cases during emergency medical or routine equipment use. Although there may have been other contributing factors, improper use of the nylon crush gasket variety of CGA 870 seals is believed to have played a major role in both fire ignition and severity.

The FDA notes that these single-use gaskets require higher torque than the elastomeric multiple-use sealing washers, and they require more torque with each successive use to seal the cylinder valve/regulator interface. Wrenches or other hand tools used to achieve this torque can deform the crush gasket and damage the cylinder valve and regulator, resulting in oxygen leaking across the gasket. This apparently causes "flow friction" from O2 leaking across the gasket surface and producing thermal energy igniting the nylon material.

The FDA and NIOSH advise against reuse of plastic crush gaskets. Other recommended precautions include "cracking" cylinder valves to allow expulsion of foreign matter from the foreign port prior to regulator attachment; use of manufacturer-recommended sealing gaskets; and visually verifying that the regulator and seal are in good condition prior to connecting the valve.

Hand-tightening the T-handle is also advised to reduce the risk for damage associated with wrenches and other hand tools. The post valve should then be opened slowly while maintaining a grip on the valve wrench to allow rapid closure if gas escapes at the junction.

Additional information regarding the proper use of CGA 870 seals may be obtained by contacting April Stubbs-Smith, Office of Surveillance and Biometrics (HFZ-510), 1350 Piccard Drive, Rockville, Maryland 20850. Questions may also be submitted by fax to 1-301-594-2968 or by e-mail at, and voicemail messages left at 1-301-594-0650 will be returned as soon as possible.

Healthcare professionals are encouraged to report adverse events related to use of CGA 870 seals to the FDA's MedWatch reporting program by phone at 1-800-FDA-1088, by fax at 1-800-FDA-0178, online at, or by mail to 5600 Fishers Lane, Rockville, MD 20852-9787.