Filtration Troubleshooting Guide

PRACTICAL STARTING POINTS FOR COMMON FILTRATION PROBLEMS

Filtration systems tend to fail in fairly predictable ways. The cause is almost always one of a handful of issues: the wrong media, fluctuating upstream conditions, incorrect system sizing, or a mismatch between what the filtration was designed to handle and what it is actually seeing. This guide covers the most common problems PS Filter encounters in the field, along with practical starting points for diagnosis. Process conditions vary, so every system should be evaluated individually, but these are reliable places to start.

If you are working through a persistent problem and would like a second opinion, we are glad to help.

Why Are My Filters Plugging Too Quickly?

Filters that plug or blind ahead of schedule are one of the most common complaints in industrial filtration. The cause is almost always either the wrong media for the contaminant type or a problem originating upstream of the filter itself. When filters are plugging faster than expected, it typically means the system is seeing more than it was designed for, or seeing something different altogether.

Possible Causes:

• Oil-coated solids coating and binding filter media
• Wax or hydrocarbon fouling
• Fine particles blinding the media surface
• Incorrect micron rating for the particle size distribution in the stream

What to Check:

• Identify the contaminant type: dry particulate solids behave very differently than hydrocarbon or wax fouling, and media suited to one may plug almost immediately with the other
• Review upstream conditions for process upsets or equipment issues contributing to elevated contaminant loading
• Confirm the selected micron rating is appropriate for the particle size being captured
• Evaluate whether adequate pre-filtration is in place before the primary filter

Why Is Differential Pressure Building Up Too Fast?

High differential pressure means your filter is working harder than it should be. Left unaddressed, it shortens filter life, increases changeout costs, and can signal a larger system issue upstream. Differential pressure is a normal operating variable, but rapid buildup or a sustained high reading points to a loading problem, a sizing issue, or both.

Possible Causes:

• High solids concentration in the feed stream
• Rapid fouling from upstream process upsets
• Inadequate pre-filtration ahead of the primary filter
• System undersized for actual flow rate or contaminant load

What to Check:

• Compare solids concentration in the feed stream against the original design basis
• Confirm actual operating flow rate against design — even modest overflows can significantly reduce filter life
• Review changeout frequency relative to expectations
• If differential pressure builds quickly after every changeout, evaluate pre-filtration as the first upgrade

Why Are Contaminants Passing Through My Filtration System?

When a filtration system is not removing what it should, the problem is usually the media, the system design, or a gap between expected and actual operating conditions. One of the most common and least obvious causes is the misapplication of nominal-rated versus absolute-rated filters. A nominal-rated filter captures a percentage of particles at a given micron size, while an absolute-rated filter captures virtually all particles at or above that size. When absolute removal efficiency is required, a nominal-rated filter will consistently underperform.

Possible Causes:

• Incorrect filter media for the contaminant type
• Nominal-rated filter used where absolute-rated media is required
• Bypass around filter media due to poor sealing or improper installation
• Channeling through filter beds in carbon or multi-media systems

What to Check:

• Clarify the required removal efficiency and confirm the appropriate micron rating
• Inspect the system for bypass pathways: gaps in sealing, improper installation, or worn components
• For bulk media systems, assess flow distribution as a potential source of channeling
• Review operating conditions against the original system design

Why Is My Activated Carbon System Not Performing?

Activated carbon is highly effective when properly designed and operated, but it underperforms when contact time is insufficient, flow distribution is uneven, or the wrong carbon has been selected. Empty Bed Contact Time (EBCT) is the key design parameter: it measures how long process fluid is in contact with the carbon bed, and directly affects how much contaminant the system can remove. If EBCT is too low, the carbon will not adsorb the target compounds effectively, regardless of how much carbon is in the vessel.

Possible Causes:

• Channeling through the carbon bed
• Insufficient EBCT for the target contaminants
• High contaminant loading exceeding the carbon's adsorption capacity
• Incorrect carbon type or mesh size for the application

What to Check:

• Calculate EBCT and confirm it meets the minimum required for your contaminants
• Assess flow distribution and inlet design for channeling issues
• Check contaminant levels against the system's design loading
• Review carbon selection: the right pore structure and surface area for your target compound is not always the most readily available option

Why Is Liquid Carrying Over Into My Gas System?

Liquid carryover into downstream gas equipment is a serious operational problem that can damage compressors, turbines, and other sensitive equipment. It typically points to a coalescing issue or an upstream condition that was not accounted for in the original design. A coalescer works by capturing fine liquid droplets and allowing them to merge into larger droplets that drain away from the gas stream. When carryover occurs, it usually means the coalescer is not capturing effectively, or that coalesced droplets are re-entraining because gas velocity is too high.

Possible Causes:

• Inadequate coalescing efficiency for the droplet size present
• Gas velocity exceeding the design limit of the coalescer
• Improper coalescer selection for the liquid type or loading
• Insufficient upstream gas-liquid separation before the coalescer

What to Check:

• Compare actual gas flow rates against the design capacity of the coalescing element
• Review upstream separation to confirm bulk liquids are being removed before reaching the coalescer
• Assess liquid loading against design parameters
• Evaluate coalescer element selection for compatibility with the liquid type and droplet size distribution

Not Finding Your Problem Here?

The issues covered above are common starting points, but filtration problems are often application-specific. Process conditions, contaminant chemistry, system design, and operating history all affect how a filtration system behaves and how it fails. PS Filter has been working through these kinds of challenges across oil and gas, water treatment, food and beverage, and other industrial sectors since 1986. If your problem does not fit neatly into the categories above, we would be glad to take a look.