Oxygen Regulator Fire Caused by Use of Two Yoke Washers
Hazard [Health Devices Nov 1990;19(11):426-7]
An ECRI investigation of a fire that occurred between an oxygen regulator
and an E-cylinder valve revealed that the fire resulted from the use of two washers
between the regulator body and the E-cylinder yoke. In this incident, a specific model
oxygen regulator, which had a durable washer, had been placed on a new E-cylinder without
first removing the cylinder's disposable washer. The use of two washers allowed an oxygen
leak on the high-pressure side of the regulator, which, in the presence of minor
hydrocarbon contamination, resulted in a flash fire between the regulator and the cylinder
Most new oxygen regulators are supplied with a plastic or nylon yoke
washer that may develop leaks with repeated use. Hospitals tend to remove these washers
and use the disposable yoke washer that is commonly supplied with a new oxygen cylinder.
However, this model regulator is supplied with a replaceable, durable, partially metallic
yoke washer that is less susceptible to developing leaks. Users familiar with nylon
washers may not be aware that this regulator has a more durable washer, especially since
this regulator is most commonly used in the prehospital environment. In addition, the
manufacturer's operating instructions and labeling do not inform users of the washer's new
design and use in its regulator. At least one other regulator manufacturer, of those known
to ECRI, also markets regulators with durable yoke washers.
With the new design, it is essential that any washer present on an
oxygen cylinder yoke be removed before installing the oxygen regulator. Only one washer
of any type should be used at any time. We encourage all manufacturers of oxygen
cylinder regulators equipped with durable yoke washers to label their regulators with
instructions to remove the yoke washer on the cylinder before installing the regulator. In
the interim, we urge users to follow the recommendations below.
- Determine whether your oxygen regulators are equipped with a durable
yoke washer. If so, affix a label or tag stating: This regulator is
equipped with a durable yoke washer. Remove any washers from the oxygen tank
cylinder before installing the regulator.
- Ensure that all respiratory therapy, nursing
(including nurses aides), emergency medicine, and anesthesia personnel are
made aware of this report.
- If you are uncertain whether your oxygen regulators
are equipped with a durable washer, contact the regulator
- Regulators, High-Pressure Gas [13-323]
- Medical Gas Cylinders [16-501]
Cause of Device-Related Incident
Device factor: Design/labeling error
User error: Device misassembly
External factor: Medical gas and vacuum supplies
Mechanism of Injury or Death