Maintenance criteria for high-efficiency air supply ceiling filters (including pre-filter), applicable on-site and easy to use
I. Core point: Check the pressure difference (priority, based on national standards)
1. High-efficiency filters (end H13/H14)
Initial resistance at factory: 220-250 Pa
Trigger for replacement: Measured resistance ≥ 2 times initial resistance
Example: Initial resistance 250 Pa → Must replace when it reaches 500 Pa
Daily control: Continuous rapid increase in pressure difference (short-term surge) → Pre-filter failure, conduct early investigation
2. Medium-efficiency filters (F8/F9)
Initial resistance: 80-120 Pa
Replacement: Resistance exceeds 1.8 times initial resistance / Pressure difference gauge reaches full scale, air volume decreases
3. Primary-efficiency filters (G4)
Recoverable type: Dirty blockage, blackening, pressure difference rises → Clean 2-3 times and then directly scrap and replace
One-time type: Significant increase in pressure difference / Severe visible dust accumulation directly replace
II. Check detection data (GMP / Cleanroom must check)
PAO leak detection fails: frame leakage, filter material leakage. No matter what the pressure difference is, replace immediately
Room cleanliness not up to standard， particle count exceeds limit， after excluding other leakage points， directly replace the end high-efficiency filter
Outlet air speed significantly low， no wind locally / Outflow skewed， filter material severely clogged
III. Check usage period (mandatory replacement to prevent hidden failure)
Conventional clean environment (pharmaceutical / electronics / aseptic)：
Primary efficiency： 3-6 months (cleaning / replacement)
Medium efficiency： 6-12 months must replace
High efficiency： Mandatory replacement after 2 years (even if pressure difference does not reach， it is recommended to replace to prevent aging， delamination， and glass fiber falling off)
High dust， high humidity， frequent disinfection and fumigation environment： All cycles are shortened by 30%-50%
IV. Visual inspection + on-site intuitive judgment (inspection can be done during patrol)
Outlet panel， uniform flow membrane blackened， obvious dust accumulation
Air supply has odor， dust sensation， still has dirty traces after disinfection
Filter frame sealing glue cracked， de-gummed， damp and moldy
Fan frequency is very high， but air volume still cannot be increased