Regarding the issue of oxygen degreasing
Thread Content
I supplied my client with a batch of imported bellows valves; to avoid being perceived as advertising, I won’t mention the brand names. Now, let me discuss my own issues: 1. Initially, the client specified that the medium to be used was helium, with a pressure of 2 bar and a temperature of room temperature (20°C). 2. The valves provided were DN50 welded bellows valves, and it was clearly stated on the valve bodies that they could not be used with oxygen. 3. The client suddenly asked if some of these valves could be used in a mixture of 10% oxygen and 90% helium, and whether they could be tried out for this purpose. I consulted the factory, and they replied: “What’s really important when using oxygen is to employ lubricants that are suitable for oxygen. For example, in the event that the bellows break, the oxygen will come into contact with the lubricants. If the lubricants used are not suitable for oxygen, it could lead to ignition, as oxygen is flammable, even at a concentration of 10%. As for the costs, I’ll check that for you.” My question now is: if, as the factory says, a mixture of 10% oxygen and 90% helium is dangerous, then what about pure air, which also contains 20% oxygen? I’ve never heard of any valve requiring degreasing when used with air! So I would like to ask everyone: for media containing oxygen, at what concentration is degreasing necessary? If the factory’s response is related to high-concentration oxygen, it should be quite professional; but as for low-concentration oxygen mixtures, should they be tried out? Thank you all
Hehe, imported oxygen needs to be degreased – even 0.01% of impurities have to be removed. As for domestically produced oxygen, there’s no need for any degreasing at all
As long as the oxygen content is higher than that in air, finger removal is necessary.
For those that use oxygen, degreasing is necessary to prevent problems during future operation; Blue Gold can be used for degreasing
Thank you for your reply: The medium is a mixture of 90% He and 10% oxygen, which should be safer than air. Is degreasing also necessary?
I’m sorry; I’ve been working overtime these days and couldn’t reply in time! The oxygen content in the air is 20%, while that in the customer’s medium is only 10%. Do you mean that degreasing is not necessary in this case?
Sorry for the late reply! I understand that high-concentration oxygen or pure oxygen requires degreasing, or the use of lubricants specifically designed for oxygen. Air also contains 20% oxygen. I have used some imported valves such as Swagelok, Parker, and Fisher, but in air-filled environments, even at a pressure of 40 Mpa, there is no need for oxygen cleaning – could you explain this in more detail? Thank you!
The air has not been degassed; previously, I encountered one case where the value was above 40%, and in that case degassing was required