Maintain Coalescing Filters to Prevent Poor Engine Performance


Extensive sludge discharge shown in the photo below the coalescing filter indicates it is poorly maintained

There is so much information available about selecting the right coalescing filter type and size. You can read for hours about how coalescing filters work and where to place them in order to reach the desired outcome for the oil carryover and cleanliness in high pressure CNG fuel lines.  Coalescing filters are positioned in multiple locations along the fueling station CNG lines, in the fuel dispensers and in the CNG vehicle high pressure fuel system lines.  The specification sheets for coalescing filters are full of details including the oil carryover Parts Per Million weight (PPMw) and micron size of the particles that will be trapped.

It is paramount to pay close attention to these details, as a properly selected and placed coalescing filter ensures that the gas used in CNG vehicles is clean enough for the vehicle to perform well. However, even if the correct filters are selected and placed properly, substandard coalescing filter maintenance will cause excessive wear and tear of the vehicle engine and engine components.   Now, I know you may be thinking “I understand the value of a coalescing filter and would never let it get to that point”. But here’s the thing, unless these filters are part of a strictly adherence-to preventative maintenance (PM) program with documented standard work, training for the people performing the work, and detailed parts, materials and tools necessary to do the work, coalescing filter maintenance will fall to the wayside over time.

Think about it—how often do you really change the oil in your car per the manufacturer’s recommendations? Or better yet, change the oil and put gas stabilizer in your lawn equipment before the winter? Does anybody really empty a bucket of water from their hot water heater every month, or spray lubrication on all the valves in their house plumbing circuit and “work” them once a year to help insure that they will perform their function should an unfortunate event occur? (I actually do this last one.) It is the same exact principle with coalescing filter maintenance. Unless you make it a standard, routine practice in your company, it just won’t happen.

The picture above shows the familiar sight of the splatting mud-like oily material that can be present when coalescing filter maintenance is a casual task instead of being part of a comprehensive PM program. Once the coalescing filter contamination reaches this level and perhaps actually blows through the filter element, the gas downstream of the filter is highly contaminated. It’s a system. In order for the vehicle filter to do an adequate job, it has to have had the job done by each upstream filter stage. Assuming the selection and placement of filters was done well, below are our top tips to prevent poorly performing coalescing filters.

Steps to Prevent Poorly Performing Coalescing Filters

  1. Have the filter numbers and locations indicated on a PM task list. Also, have the filter numbers on the actual filter body.
  2. Make the tools required to service each different type of filter easily available and indicated on the task list.
  3. Keep the recommended materials for cleaning the filter bowl and plug readily available.
  4. Have the filter elements required for each different filter size/type in stock. Mark the element type on the task list and on the filter body itself or near the filter body. The stocked elements should be kept in a dry, clean area.
  5. Check the box when the PM task is complete.Subscribe to Our Newsletter

In addition, write down any notes that might be cause for discussion on the timing of the maintenance; such as the splatting (aka“baby poop” looking substance) shooting out of the filter when cleaning it.

Coalescing filters are just one Maintenance, Repair and Operations (MRO) item requiring regular attention. CNG Fueling stations and vehicles have wear items that should be included on a PM program. Owners & operators need trusted suppliers that can help in the repair or replacement of MRO items. InsightFuel is well suited to assist with all your materials, specialized installation equipment and services to help build & repair CNG stations better & faster and keep them running well. We specialize in fueling station high pressure CNG conveyance systems, complete timefill posts assemblies, dispenser hose assemblies and associated components. InsightFuel has the valves, fittings, bent tube assemblies and hose assemblies ready to keep your CNG vehicles running smoothly and efficiently.

InsightFuel, A refreshingly new idea for clean fuel transportation. Come to us for what we know, not just what we sell.



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