Filter Rinsing and Cleaning

Sanitization/ sterilization should be preceded by filter rinsing and cleaning using water filtered to remove particles that might clog the filter being rinsed.
If the filter is used in an application to remove undissolved particles, then rinse with cold water followed by warm water [50 ± 5 °C (113-131 °F)] to remove the soluble particles held by the filter. (NOTE: exposing filters clogged with organic residue to high temperature sanitization or sterilization with hot water or steam without rinsing and cleaning may cause the organic material to irreversibly bond to the filter media surface and prematurely foul the filter.)
Monitoring process operations and cleaning and sanitizing processes is critical. Pressure gauges G4 and G5 should be in place to monitor pressure during all procedures. Temperature gauges or sensors, especially at T2 and T3, should be in place to monitor cleaning and sanitization/sterilization to assure that proper temperatures are maintained.

Rinsing and Cleaning Procedure

Start with all valves closed.

  1. Open valves V7, V6, V8 and V10 to drain the filter system of product.
  2. Close all valves except V7 (vent) and leave V6 (drain) partially open.
  3. Open valve V2 and rinse the filter assembly with cold water
  4. When the filter housing is full (no air bubbles in the flow from V7), open V8 and V10 and partially close the vent valve V7 to continue flushing the top of the filter module. (NOTE: A steady stream of water should flow from valve V7. If not, increase the water flow rate or partially close V6, V8 and V10.)
  5. Continue until the flow from valve V10 appears clear and free of product.
  6. Adjust the inlet water temperature to warm [50 ± 5 °C (113 -131 °F)] and continue flushing the filter until the flow from valve V10 is clear.

Procedure Notes:

  1. The rinse water flow rate should be at least as high as the process flow rate.
  2. The housing vent connection needs to be large enough to allow adequate flow to the entire filter housing, especially when using 30 or 40-inch cartridges and/or multi-round housings.
  3. When switching from cold to warm water or vice versa, do so slowly to avoid large and abrupt temperature changes that may cause the filter materials to deform.
  4. If using reverse flow to rinse or clean filters, do not exceed the filter’s specified maximum differential pressure limit for reverse flow. 

With two or three stage filter systems, use the same procedure as above, but the system design should include a drain valve in between each filter housing to allow each housing to be flushed independently. This is critical because substances rinsed from prefilters must not flow to the downstream filters with smaller micron ratings.

Filters should be thoroughly rinsed before re-installation to remove residual cleaning agent.