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In oxygen components, even for high pressure oxygen service, it is possible to use organic seals, lubricants, or filling liquids, provided their oxygen compatibility has been checked. However, fire incidents in oxygen systems still occur because these materials ignite and burn. There are many reasons, such as incorrect design, contamination, faulty operation, unsuitable materials, etc., why this happens. Another cause that is overseen very often is proper maintenance on the user´s side. It is very important to replace in a component a worn out seal by the same one with identical oxygen compatibility properties. On the part of the producer or distributor of materials, batch testing and also a quality assurance system play a key role in the safety of an oxygen component. Any change in the manufacturing process of a material, or in its composition, and even its further processing may have an impact on its oxygen compatibility and finally on the component in which it is used. Numerous investigations by BAM over decades reveal the influence of minor constituents and fillers on a material´s oxygen compatibility. The test results in this paper show how important it is to regularly perform batch testing on nonmetallic materials used for oxygen service and to have a quality assurance system that helps minimize incidents where unsuitable materials are chosen by accident.
The widely held incorrect belief in the self-contained underwater breathing apparatus (SCUBA) diving community, that oxygen-enriched gas mixtures, so-called NITROX, with an oxygen content of up to 40 vol. % can be considered as regular air, has already been refuted in many papers. Now, another dangerous practice has drawn the attention. In a market study, more than 60 representative SCUBA cylinder valves were examined. Sales offices claim that all of those valves can be used for oxygen-enriched gas mixtures. The fact is that some of these cylinder valves are for air use only. By exchanging the nonmetallic materials and applying additional cleaning procedures, these air valves become so-called “oxygen clean.” Then, the valves are on sale for oxygen-enriched service. This procedure is dangerous because the labeling pretends a pseudo-safety. All of the 60 SCUBA cylinder valves were tested applying the standardized oxygen pressure surge tester at BAM. As suspected, many of the cylinder valves are not burn-out safe. In addition, different test results were received for actual new valves, for so-called new but temporarily stored valves, and for used valves. This paper reveals another dangerous practice and wants to alert the SCUBA diving community.
The general requirement, that nonmetallic materials for oxygen service must be tested and found suitable for their intended use in plants and components is the current state of technical safety. However, numerous requests of manufacturers, sales offices, and users show, that there is still a strong need for information on how these materials are tested and evaluated. Based on more than 60 years of expertise, this paper provides background information on BAM’s test approach. It explains why BAM applies additional assessment criteria on nonmetallic materials for certain use conditions. Hence, the test schedule as well as the final evaluation shall reflect the practical application in a more customer-related way in combination with a higher safety level. That is the demand of BAM’s safety philosophy.
The general requirement, that nonmetallic materials for oxygen service must be tested and found suitable for their intended use in plants and components is the current state of technical safety. However, numerous requests of manufacturers, sales offices, and users show that there is still a strong need for information on how these materials are tested and evaluated. Based on more than 60 years of expertise, this paper provides background information on BAM’s test approach. It explains why BAM applies additional assessment criteria on nonmetallic materials for certain use conditions. Hence, the test schedule as well as the final evaluation shall reflect the practical application in a more customer-related way in combination with a higher safety level. That is the demand of BAM’s safety philosophy.