To what extent does the pressure difference of the air shower hepa filter need to be replaced?

The pressure difference replacement standard of air shower high-efficiency filter is usually determined according to its final resistance, and the specific range needs to be combined with the initial resistance, the use environment, and the equipment requirements:
1. Universal replacement standard
Final resistance threshold
The final resistance of the high-efficiency filter is generally set to 2-3 times the initial resistance (usually 300-400Pa). If the device is equipped with a differential pressure gauge, replace it immediately when the resistance reaches this threshold.
Some high-precision scenarios (such as the pharmaceutical and electronics industries) may require final resistance ≤450Pa.
Estimation without differential pressure gauge
If the differential pressure meter is not installed, it can be estimated according to the running time: when the initial effect filter is normal, the resistance of the high-efficiency filter increases by about 50-100Pa every 1000 hours of operation. When the resistance is close to 300Pa, it should be replaced.
Second, special scene adjustment
High pollution environment (such as industrial dust areas): the final resistance can be advanced to 250-300Pa.
High temperature and high humidity environment: Because the filter paper is easy to delix, the resistance may increase suddenly, and the detection cycle needs to be shortened.
Biosafety laboratory: In case of microbial contamination (such as mold spots), even if the resistance is not up to standard, it needs to be replaced.
3. Operational suggestions
Differential pressure meter monitoring: preferentially refer to the differential pressure meter of the equipment, and replace it according to the final resistance value marked by the manufacturer.
Wind speed auxiliary verification: If the wind speed is lower than the standard value (such as < 25m/s) and the initial effect has been cleaned, it is necessary to check whether the pressure difference exceeds the standard.
Regular maintenance records: Set up filter files, record the resistance value during each replacement, and form trend analysis.
Iv. Reference basis
The industry standard "Clean Rooms and Associated Controlled Environments" (GB/T 25915) recommends that the final resistance be 2-3 times the initial resistance.
Some enterprises set the final resistance to 300-450Pa according to actual experience, and the specific equipment manual shall prevail.
Through the above method, the replacement time of the high-efficiency filter can be accurately judged to ensure the clean performance and operating efficiency of the air shower room.