A method for determining the replacement timing of the high-efficiency filter of the air shower transfer window based on the reading of the differential pressure gauge
The core of the judgment is based on the initial pressure difference of the high-efficiency filter, combined with the changing trend of the pressure difference gauge reading and the warning threshold, which can accurately determine whether replacement is needed. The specific method is as follows:
I. Core Judgment Criteria (Replacement is Required if any of the conditions is met)
Threshold One: Reaching twice the initial pressure difference
After the new high-efficiency filter is installed, the pressure difference recorded when the air shower system is operating stably is the initial pressure difference (conventionally 5-15Pa, subject to the equipment/filter manual).
During operation, if the reading of the differential pressure gauge continuously exceeds twice the initial differential pressure, it indicates that the filter material of the filter has been severely clogged. The air volume of the air shower will drop significantly, and the purification effect cannot be guaranteed. Immediate replacement is required.
Example: The initial pressure difference is 10Pa. When the reading remains ≥20Pa continuously, the high-efficiency filter needs to be replaced.
Threshold Two: Reaching a general warning pressure difference of 25Pa
If the initial pressure difference is not recorded, the industry-standard warning value can be adopted: when the reading of the pressure difference gauge remains ≥25Pa continuously, it is directly determined that the filter is clogged and needs to be replaced.
This threshold is the safety bottom line. Once exceeded, the load on the fan will increase significantly, and there may even be a risk of contamination in the clean area due to insufficient air volume.
Ii. Auxiliary Judgment: Analysis of Reading Change Trends
Normal trend: The differential pressure reading rises slowly with the operation time, conforming to the gradual change rule of “initial differential pressure →1.5 times the initial differential pressure →2 times the initial differential pressure”, which is a normal clogging process.
Abnormal trend
If the reading suddenly surges (such as rising from 10Pa to over 20Pa within a short period of time), it may be that the surface of the filter is covered with a large amount of dust or debris, or the filter seal has failed or the filter material is damaged. Immediate inspection and replacement are required.
If the reading remains stable at a low value for a long time (such as far below 50% of the initial pressure difference), it does not mean that replacement is not necessary. On the contrary, it may indicate that the filter is not installed tightly, the pressure guiding pipe is connected in reverse, or the filter material is damaged. It is necessary to first check for equipment faults and then determine whether to replace it.
Iii. Key Operation Precautions
The reading must be taken under valid conditions: The pressure difference must be read when the air shower system is operating stably, both door bodies are completely closed, and the primary filter is clean. Otherwise, the reading will be invalid and may lead to misjudgment.
To eliminate faults of the differential pressure gauge itself: First, confirm that the zero position of the differential pressure gauge is normal and there is no air leakage or blockage in the pressure guiding pipe to avoid incorrect judgment caused by instrument failure.
Prioritize recording the initial pressure difference: After the new filter is installed, it is essential to record the initial pressure difference in a timely manner and establish a ledger. This is the most accurate judgment benchmark and is more targeted than the general warning value.
Do not delay replacement: Once the replacement threshold is reached, the machine should be shut down as soon as possible for replacement. Otherwise, it will not only affect the air shower effect but also may cause equipment damage due to the overload operation of the fan.
Iv. Common Misjudgment Scenarios and Responses