Cause of Device-Related Incident
*Not stated

Clinical Specialty or Hospital Department
Anesthesia; Clinical/Biomedical Engineering; Emergency Medicine; Facilities Engineering; OR / Surgery; Pulmonary / Respiratory Therapy

Device Factors
*Not stated

Document Type
Frequently Asked Questions (FAQ)

External Factors
*Not stated

Mechanism of Injury or Death
*Not stated

Support System Failures
*Not stated

Tampering and/or Sabotage
*Not stated

User Errors
*Not stated

Regulators, High-Pressure Gas [13-323]

Are Aluminum Oxygen Regulators Safe?

FAQ [Health Devices Mar 1999;28(3):118]

Question. We have heard that aluminum oxygen regulators are now considered to be a fire hazard. What are the issues?

Answer. A recent advisory issued by the U.S. Food and Drug Administration (FDA) and the National Institute for Occupational Safety and Health (NIOSH) has created a lot of interest in this topic. Under certain conditions, aluminum will burn in oxygen, and the February 1999 FDA/NIOSH advisory cites several instances in which aluminum oxygen regulators used with high-pressure cylinders have caught fire.

In these instances, the fires have been initiated through either of two mechanisms: 1) particle ignition, in which debris is blown from the cylinder into the high-pressure side of the regulator with sufficient energy to ignite the aluminum in the regulator, or 2) adiabatic compression ignition, in which the gas in the regulator is recompressed as the high-pressure oxygen enters the regulator; this creates a transient high temperature that ignites flammable materials in that space, resulting in the ignition of the regulator. Adiabatic compression ignition is less of a concern in the hospital setting because regulators are not likely to become contaminated with ignitable materials, such as oil and dirt, during use or maintenance in this environment. This form of ignition is more of a concern in the prehospital setting (e.g., for emergency medical services).

In light of the incidents referenced in their advisory, both FDA and NIOSH now recommend that aluminum regulators be replaced with brass regulators, which are much less likely to ignite when used with high-pressure compressed oxygen. While replacing aluminum regulators with ignition-resistant brass is a prudent measure and may eventually be required in U.S. facilities (as is implied by the FDA/NIOSH advisory), facilities can continue to use aluminum regulators for the time being, provided that they follow simple safety precautions to reduce the likelihood of fire. For example:

  • Particle ignition can typically be avoided by following basic compressed-gas safety practices. These include clearing the cylinder valve stem (by "cracking" the cylinder valve to release a short burst of gas) before attaching a regulator and ensuring that the regulator is in a no-flow state before attaching it to the cylinder. In the aluminum regulator fires that ECRI has investigated, such basic safety practices were violated. Also, while not a sure preventive measure, the use of a sintered inlet filter disk rather than an easily displaced mesh screen inlet filter can help reduce the fire risk. (One major regulator manufacturer has made this change to its regulators.)
  • The risk of adiabatic compression ignition can be minimized both by keeping all regulators free of oils, dirt, and other combustible substances and by opening the cylinder valve slowly, rather than rapidly.

For the time being, we recommend educating users in the safe practices for compressed gases while planning to replace aluminum regulators with brass ones in a prudent manner. For a detailed list of safe practices, refer to the Compressed Gas Association's (CGA) pamphlet P-2, Characteristics and Safe Handling of Medical Gases (CGA, 1725 Jefferson Davis Highway, Suite 1004, Arlington VA 22202-4102; Phone: [800] 827-5242, [703] 412-0890).


Regulators, High-Pressure Gas [13-323]

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