Particles appearing downstream immediately after a filter bag change do not automatically mean the micron rating is too coarse. Start by checking the installed bag, its sealing interface and the sampling method. A finer bag cannot correct liquid flowing around an incorrectly seated collar.
This checklist helps maintenance and purchasing teams gather evidence before ordering replacement PP filter bags or a different single bag filter housing. It is a diagnostic worksheet, not a substitute for the equipment manual.
Separate three different problems
| Observation | Possible explanation | Useful next check |
|---|---|---|
| Particles appear just after restart, then decline | Residual contamination downstream, installation debris or sampling contamination | Compare timed samples using the same documented sampling procedure |
| Particles remain despite a new bag | Seal bypass, damaged media, unsuitable retention performance or another contamination source | Inspect the removed bag and installation, then compare upstream and downstream particle data |
| Abrupt pressure-drop change with deteriorating filtrate | A change in flow, instrumentation or filter condition | Review flow and pressure records before interpreting the event |
These patterns suggest checks; none proves a failure mechanism. Appearance alone also cannot establish particle size or filtration efficiency.
Inspect the sealing path before changing the rating
Before opening the housing, trained personnel must follow its shutdown and isolation procedure, verify that pressure has been released and confirm safe temperature and chemical conditions. Never loosen a pressurized cover.
- Confirm the bag part number, material and collar construction against the approved specification.
- Check that the collar contacts the intended sealing surface all around. Look for folds, trapped debris, cuts and deformation.
- Inspect the basket seat and retaining components. A bag that fits the basket body can still have an incompatible top seal.
- Check that the bag reaches its intended position without bunching, twisting or an unsupported section.
- Inspect the seam, bottom and collar attachment for visible damage; retain the used bag and its lot label for investigation.
Eaton’s SENTINEL technical sheet specifically recommends an insertion tool to align its bags within the restrainer basket. This illustrates why installation matters; it does not establish compatibility or performance for another bag-and-housing combination.
For dimensions and collar identification, use the ring and collar fit guide. For construction questions, see welded versus sewn filter bag seams.
Make the comparison fair
Record flow, liquid temperature, upstream pressure, downstream pressure and time since restart. Use identified sampling points and clean containers. A downstream pipe that was contaminated during maintenance can obscure the result from a correctly installed bag.
Compare like-for-like operating conditions. Low differential pressure alone does not demonstrate bypass: a clean filter, lower flow or a gauge problem can also produce a low reading. Conversely, pressure readings do not establish the absence of bypass.
When should you trial a finer filter bag?
Consider a retention trial after checking fit, installation and media integrity. Ask for the efficiency at the relevant particle size and the test conditions, rather than comparing micron labels alone. Keep liquid, flow and sampling consistent between trials and record filtrate quality, pressure trend and usable batch volume.
Use the filter bag efficiency report guide to specify supporting evidence. Do not assume a smaller nominal number guarantees the required outlet cleanliness.
Send an evidence package for technical review
Request a filter bag and housing review from INCE filtration with the housing model, bag code, collar measurements, basket dimensions, installation photographs, liquid conditions, flow and paired sample results. Identify whether the problem began after changing supplier, material, rating or maintenance procedure.
FAQ
Can a tighter micron rating stop seal bypass?
No. The sealing interface must first be corrected and verified. Retention selection addresses liquid passing through the media.
Does a clean-looking bag prove that it is installed incorrectly?
No. Interpret its appearance alongside the contaminant load, operating time, flow and sampling evidence.
Technical reference
Eaton SENTINEL filter bag technical sheet, consulted for its product-specific installation guidance. No Eaton performance values are assigned to INCE products here.
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