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This blog addresses the second question in ‘How to Determine the Appropriate Regulator‘ as part of our ‘Choosing the Correct Regulator’ series: What media is being used? Air, oxygen, inert gases, natural gas, etc
When choosing a regulator, it will be necessary to understand the media coming in contact with its wetted parts. Some gases could be caustic to the diaphragm, seals or even the body parts. There are options for regulators to combat some of these issues.
The most common diaphragm material is Buna-N (nitrile). Other common options would be Viton and silicone. One of the most common applications for Viton is using gas with high ozone levels. Buna-N does not react well to higher levels of ozone. Certain kinds of bleach will also adversely affect Buna-N diaphragms and seals. Viton would be a better choice for contact with bleaching chemicals. Viton reacts well with many different kinds of chemicals. A typical application for silicone is arctic ambient temperatures. The silicone stays more compliant as temperatures drop below 0 Farenheight when compared to Buna-N. Silicone materials also increase the temperature range on the high end, moving from 160 °F to 194 °F when switching from Buna-N. Some diaphragms, such as stainless steel, are generally used in higher pressure regulators. There are many tools online to help with material compatibility. We have found that ColePalmers website has proven very helpful. https://www.coleparmer.com/chemical-resistance
Common body materials used in air pressure regulator construction are aluminum, zinc, brass, plastic and stainless steel. 316 Stainless Steel is a common ingredient for a regulator that needs better corrosion resistance than an aluminum regulator. This corrosion concern could come from excess moisture or external consideration such as salt air. Another common concern is applications that use sour natural gas. For these applications, NACE-compliant regulators need to be considered. The main culprit in sour gas is hydrogen sulfide. Hydrogen sulfide attacks many yellow metals and certain plastics, including Buna-N. Common substitutes for Buna include Viton for sour gas applications. Besides diaphragms and body materials, there are other internal components to consider. Items such as pintle assembly and valve seat materials must be reviewed for compatibility with the application.
There should be healthy consideration of exhaust or relief gas when using media other than air. The use of a non-relieving regulator and/or a tapped exhaust port can help reduce the risk of exposure to these harmful gases. Under normal circumstances, non-relieving regulators will not vent to the atmosphere. See our blog on non-relieving regulators for more information. Tapped exhausts are used with fitting and pipe to vent harmful gasses to a safer location.
If you have any questions regarding your next application, don’t hesitate to contact our technical support team.