FDA/NIOSH Oxygen Regulator Fires resulting from incorrect us

[DCMed124]

FDA AND NIOSH Public Health Notification: Oxygen Regulator Fires Resulting

from Incorrect Use of CGA 870 Seals

(You are encouraged to copy and distribute this information)

Issued: April 24, 2006

Dear Colleagues:

This is to alert you to the danger of fires at the interface of oxygen

regulators and cylinder valves because of incorrect use of CGA 870 seals,

and to point out an important precaution you can take to avoid such fires.

Background

FDA has received 12 reports in which regulators used with oxygen cylinders

have burned or exploded, in some cases injuring personnel. Some of the

incidents occurred during emergency medical use or during routine equipment

checks. FDA and NIOSH believe that improper use of gaskets/washers in these

regulators was a major factor in both the ignition and severity of the

fires, although there are likely other contributing factors.

Two types of washers, referred to as CGA 870 seals, are commonly used to

create the seal at the cylinder valve / regulator interface: The type

required by many regulator manufacturers is a metal-bound elastomeric

sealing washer that is designed for multiple use applications. The other

common type, often supplied free-of-charge with refilled oxygen cylinders,

is a plastic (usually Nylon ®) crush gasket suitable for single use

applications.

The nylon crush gaskets require higher torque than the elastomeric sealing

washers in order to seal the cylinder valve / regulator interface, and if

they are used again, they require more torque with each successive use. The

cylinder valve / regulator connection is designed to be hand-tightened. If

the crush gaskets are re-used, the need for increased torque may require

using a wrench or other hand tool, which can deform the crush gasket and

damage the cylinder valve and regulator. This can result in leakage of

oxygen past the cylinder valve seat and across the nylon crush gasket.

According to a forensic analysis supported by FDA and NIOSH, “flow

friction†caused by this leakage of compressed oxygen across the surface of

the crush gasket may produce enough thermal energy to spontaneously ignite

the nylon gasket material.

Recommendations

FDA and NIOSH recommend that plastic crush gaskets never be reused, as they

may require additional torque to obtain the necessary seal with each

subsequent use. This can deform the gasket, increasing the likelihood that

oxygen will leak around the seal and ignite.

The following general safety precautions should also be taken to avoid

explosions, tank ruptures and fires from oxygen regulators.

·    Always “crack†cylinder valves (open the valve just enough to allow

gas to escape for a very short time) before attaching regulators in order

to expel foreign matter from the outlet port of the valve.

·    Always follow the regulator manufacturer’s instructions for

attaching the regulator to an oxygen cylinder.

·    Always use the sealing gasket specified by the regulator

manufacturer.

·    Always inspect the regulator and CGA 870 seal before attaching it

to the valve to insure that the regulator and seal are in good condition

and the regulator is equipped with only one integral metal and rubber seal

that is in good condition. Avoid plastic seals.

·    Tighten the T-handle firmly by hand, but do not use wrenches or

other hand tools that may over-torque the handle.

·    Open the post valve slowly, while maintaining a grip on the valve

wrench so that it can be closed quickly if gas escapes at the juncture of

the regulator and valve.

Figure 1 : Examples of crush gaskets available for CGA 870 type medical

post valves

.Figure 2: Examples of some sealing washers available for CGA 870 Style

medical post valves.

Reporting to FDA

To report your experience regarding the devices in this Notification,

please use MedWatch, the FDA’s voluntary reporting program. You may submit

reports to MedWatch by phone at 1-800-FDA-1088; by FAX at 1-800-FDA-0178;

by mail to MedWatch, Food and Drug Administration, 5600 Fishers Lane,

Rockville, MD 20857-9787; or online at

http://www.fda.gov/medwatch/report.htm.

Getting More Information

If you have questions about this notification, please contact the April

Stubbs-Smith, Office of Surveillance and Biometrics (HFZ-510), 1350 Piccard

Drive, Rockville, Maryland, 20850, by Fax at 301-594-2968, or by e-mail at

phann@cdrh.fda.gov. You may also leave a voicemail message at 301-594-0650

and we will return your call as soon as possible.

FDA medical device Public Health Notifications are available on the

Internet at http://www.fda.gov/cdrh/safety.html. You can also be notified

through email on the day the safety notification is released by subscribing

to our list server. To subscribe, visit:

http://list.nih.gov/archives/dev-alert.html.

    Sincerely yours,

Daniel Schultz, MD

Director

Center for Devices and Radiological Health

Food and Drug Administration

Nancy Stout, Ed. D

Director, Division of Safety Research

CDC, NIOSH

Updated April 25, 2006

[TTLWHKR]

What type of gaskets do they recommend for use?

Mine looks like a round brass frame with a blue, rubber gasket in the center. I installed that myself, it came with a small green, plastic gasket. It seemed to leak when I first tried it, that's why I switched.