Foothills Gas Products Blog

Clean, Dry Gas – Yikes, Not Always!!!

Posted by Foothills Industrial Products on Sep 10, 2019 3:54:24 PM

It’s a saying we’ve all heard – our gas is clean and dry.  For many years that may have been the case but all of a sudden the regulators have frozen off, or the sample probes are clogged, and the Gas Chromatograph is in alarm and not providing results due to no gas flow. You are puzzled. How could this be happening if the gas is clean and dry?  

This may be a story you know all too well.

Truth be told, it is more common for gas to have some level of contamination than not at all and there are many sources of contamination possible as gas moves through the transmission and distribution chain. The good news here is that these contaminants can be mitigated completely by implementing an effective filtration plan.


For a filtration plan to be effective, you must have an idea of the operating conditions of your line, and/or a gas sample to determine the cause of your problems. There are many different types of contaminants, from liquids to solids, that come from an array of different sources. In our experience we have seen everything from ‘Black Death’, a molecular sized ferrous oxide particulate that clogged the orifices of solenoids and thermocouples, to a Tim Hortons cup that shut off a regulator, left behind by a welder.

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Liquids such as water can be present due to phase change, or methanol or glycol which was added upstream, can still exist if not properly removed.  Compressor oils are another common contaminant often found downstream of compressor stations.  A station or system designed with coalescing filters, to remove liquids specifically, will eliminate hydrate formation at your pressure cut due to the Joules Thompson Effect, and a liquid stop or liquid drain in your sample conditioning system will protect your analyzers from upset or downtime due to contamination.

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As mentioned previously, contaminants in particulate form can also be pain in the butt! Particulate contamination comes from sources such as welding slag left behind from repair jobs, or not completely removed in a hydrostatic wash. But more often than not, the culprit is not so obvious.  Knowledge about the source and type of contamination in your operation can feel like solving a murder mystery and can bring frustration.  This is when an in-depth gas sample and analysis can provide clues and lead you towards finding a solution. If your process utilizes natural gas, air, or any inert gas, then a multistage coalescing and particulate filter probably makes the most sense.

Welker Filter

We know contaminants can have an affect on your entire operation and it is often your instruments that indicate a contamination problem exists. Unfortunately, in most scenarios you end up with a cost that could have been prevented if you allow contamination to reach the instrument at all. Analytical instruments, like your Gas Chromatograph or H2S analyzers, that experience contamination could result in costly repairs or down time. Sample probes can be easily clogged and may need to be fully replaced if contamination persists.

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Surely by now this story sounds familiar. The alarm bells are going off and the light bulb above your head just flicked on. Thoughts about the many areas where you could improve your own operation are flooding your noggin. Whether this is the case, or you are sitting here grinning ear to ear feeling like a hero because you've already made the right decision to protect your operation using filtration, one thing is for sure: investing in station, system, process or instrument filters up front will save you time and money in the long term.

Filter selection and placement should be a key part of your design consideration and if you understand the parameters that affect your operation, you will confidently select the best filter for the application.

Let us help you understand what the right filter for the application is.

It’s a contaminated world out there. Click here to find out how you can be the hero of your operation.

Topics: Liquid Contamination, Oil Contamination, Natural Gas Filtration, Filters, Clean Natural Gas, Particulate Contamination, Filtration, Contamination, Contaminants

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