07 Apr Corrosion Control of Corrosive Gas
A facility without proper or functioning corrosion control and prevention is risking significant damage to both their facility and possibly the products they are making. Corrosive environments are classified by ISA 71.04:2013 and are denoted with G1/Mild, G2/Moderate, G3/Harsh or G4/Severe ratings. Depending on the facility the acceptable level of corrosive environemnt classification can vary but most facilities that implement corrosion control methods are trying to achive G1/Mild – which is not as difficult as some companies would have you believe.
The reason many companies struggle to offer corrosion control solutions that actually work has to do with the uniuqeness of molecular filtration and the disconnect between test standards and real world applications. If you’re a subscriber to our blog you should be used to us picking apart filter test methods as they are typically not designed to replicate real world environments, which in turn leads to mis-information, mis-application, and poor results. This is more true in Molecular filtration than any other.
So what makes Molecular Filtration Different?
Unlike particles – which tend to agglomerate – corrosive gas, and all other molecular particles for that matter, spread out away from eachother. This creates very low concentrations which make removal difficult, especially for thin-bed blended or embedded carbon filter medias which due to their design do not have uniform distribution of sorbent throughout the media. These medias test well in a lab however becasue the industry standard method is derived from gas mask test procedures with very high concentrations. It’s easier to catch 99% of a 250,000ppb concentration than 99% of 10ppb concentration.
Industrial Corrosion Control Gasses of Concern:
As defined in the ISA 71.04:2013 classification system the gasses we typically would test for in a corrosive environemtn would be:
- Hydrogn Sulfide
- Sulfer Dioxide
- Sulfer Trioxide
- Nitrogen Oxides
- Hydrogen Fluoride
Other site-specific gasses may be tested for if there is a specific process that either generates or is sensetive to them. Most important to remember in molecular fitlration is to have a combination of the following:
- Avoid blended media – if multiple media/sorbents are needed do them in series with eachother
- Develop a testing schedule so you know how close to breakthrough you are
- Have a filter and frame/housing that is tested globally – meaning that leakage is tested not just at the filter or housing level but in conjunction with eachother (2 products that test well independantly may be horrible together)
- Understand your sorbents/medias and have the test reports you get from suppliers be at real world low-concentration levels.
Of course always feel free to contact us with specific questions or if you’d like us to come out and meet on-site we have relationships all over the globe to get you in contact with a local molecular filtration expert!