01Identify each filter before cleaning
Record the filter model, construction, residue and service history. Tag filters with prior pressure-drop problems, deformation or repairs so they can be evaluated individually.
Confirm that the media, support, welds and seals can withstand the cleaning cycle. A filter’s production temperature alone does not establish its cleaning limit.
02Check for damage and residue
Inspect for tears, bulges and deformation. Examine end welds and sealing faces. Use the agreed integrity test where required, since a damaged filter can show unusually low pressure drop.
Check the pores and ends for residue, then follow the agreed finishing, drying and storage procedures. A cleaned filter can pick up dust again if left uncovered.
03Compare pressure drop on equal terms
Use the same test fluid, temperature, flow and fixture. Record the test points and the reference filter. A change in viscosity can change the reading even when the filter is unchanged.
For high readings, check the fixture, temperature and flow before suspecting trapped residue. For low readings, check for bypass, seal leaks or damage to the media.
04Keep a reuse log
Record filter ID, before-and-after pressure drop, cycle batch, reuse count and integrity results. Assess filters with recurring anomalies separately.
When buying a furnace, bring representative filters and residue samples. Agree on what to measure before and after the cleaning trial.