Qualifying Items For Medical Gas Service

GAWDA members often want to know the difference between parts, components and systems cleaned for oxygen service, and the same items being qualified for medical gas service. Just like medical gases, the biggest difference between an oxygen clean part or component and a similar item qualified for medical gas service is the “paperwork pedigree.”

An essential step in preparing items for both oxygen and medical gas service is removing residual oil or grease by some sort of cleaning process. Residual hydrocarbon contamination can violently react with oxygen or contaminate medical gas systems. While this type of cleaning is not mandatory for industrial gas services like nitrogen and argon, we consider it a requirement if the items are to be used in medical gas systems such as Nitrogen USP and Carbon Dioxide USP.

Over the years, medical gas manufacturers and their suppliers have employed a variety of cleaning agents and processes. Long gone are the “good old days” when cleaning parts for oxygen service meant dipping them in Freon 11 or TCE, and allowing the solvent to quickly evaporate from the part. While highly effective, these solvents had significant drawbacks, including damage to the ozone layer, health risks to the workforce, and the toxicity of residual solvents.

Today the industry has largely phased out these solvents in favor of more environmentally compatible and user-friendly materials. Unfortunately, these replacement solvents by themselves are often not as effective. Suppliers have had to turn to technologies such as heated acid/caustic dip baths, ultrasonic cleaning and detergent based solvents, which under properly controlled and managed conditions get the job done.

A key determination between just oxygen clean and items for medical gas service is ensuring that all potential contaminants, including residual solvents, are removed. Understanding how your supplier cleans and inspects your medical gas parts and components, and what solvents are involved is one of the key administrative steps in transitioning an item from simply oxygen clean to becoming qualified for medical gas service. It has become standard procedure for medical gas companies to collect information from their vendors about their cleaning processes, and what types of inspections, such as visual or black light examinations, they conduct.

Odor testing is another key inspection step for any item going into medical gas service. We recommend that when solvents with toxic ingredients are used, the presence of the solvent should be detectable by a sniff test well before any toxic concentration would be present.

It is important that you have an agreement with suppliers to notify you of changes in solvents or cleaning processes so you can determine any impact to your operation. Regular suppliers to the medical gas industry have recognized these requirements and will be able to supply the information you need about their cleaning processes. If your firm purchases parts, components and systems from local vendors, companies that do not regularly supply the medical gas industry, or if you purchase industrial items and have them cleaned locally, you should invest the time and effort to qualify your vendor’s cleaning processes for medical gas service.

Dust and particulate matter, just like oil and grease, are an unacceptable contamination for items used in industrial oxygen or any medical gas service. It is important that items be adequately protected from contamination during shipment and storage. Nowadays, parts like valves and fittings for medical gas service typically arrive in sealed plastic bags. Larger items like regulators that are not bagged should have a threaded plastic plug in the open ends, even if packaged inside a box. Do not accept parts or components for medical gas service that are shipped loose, unprotected, or arrive in a box but with the openings unprotected. Openings should not be protected with tape or other items that could leave a sticky residue.

Many items such as valves, fittings and hoses visually look the same, so to avoid potential confusion between medically qualified and unqualified items, store them separately using proper segregation procedures. Prior to using an item from inventory in medical gas service, two important steps should be taken: First, inspect it to ensure that it is not damaged or contaminated. Second, perform an odor test to check for cleaning process residues.

Ensuring the integrity and safety of parts, components and systems used in medical gas service is a crucial element in a comprehensive cGMP compliance program.


Gases and Welding Distributors Association
Meet the Author
J. Robert Yeoman, GAWDA’s medical gases consultant, is managing director of B&R Compliance Associates LLC in Lehigh Valley, Pennsylvania.