The method for judging the normal state of the differential pressure gauge of the air shower transfer window
The differential pressure gauge of the air shower transfer window is mainly used to monitor the resistance changes of the high-efficiency filter. Whether its reading is normal directly affects the purification effect of the air shower system and the operating status of the equipment. The following judgment methods are explained step by step and are applicable to on-site operation, maintenance and training scenarios.
I. Prerequisite: Confirm that the foundation condition of the differential pressure gauge is normal
Appearance and installation inspection
The dial is undamaged, the scales are clear, and the hands are not stuck.
Correct installation position: It should be installed vertically at an easily observable position outside the transfer window. The pressure guiding pipe should be firmly connected without any bends or air leaks.
The interface of the pressure guiding pipe should be free from dust and oil stains. The positive pressure end should be connected upstream of the high-efficiency filter, and the negative pressure end should be connected downstream (or connected as indicated in the equipment manual).
Zero position calibration verification
When the equipment is completely powered off and shut down, and there is no air flow through the air shower system, the pointer of the differential pressure gauge should point to zero.
If the zero position is offset, you can gently rotate the zero adjustment knob on the dial (for some models, the dial case needs to be opened) to adjust the pointer to the zero position.
If the zero position cannot be calibrated, it indicates an internal fault in the differential pressure gauge and it needs to be replaced.
Ii. Normal Reading Judgment under Operating conditions
Obtain the initial pressure difference reference value
After the new high-efficiency filter is installed, start the air shower system and run it stably for 5 to 10 minutes. Record the reading of the differential pressure gauge at this time, which is the initial differential pressure.
This value must comply with the technical requirements of the equipment. Generally, the initial pressure difference of the high-efficiency filter of the air shower transfer window is 5-15Pa (specifically subject to the equipment manual or filter parameters).
Normal operating pressure difference range
During operation, the reading of the differential pressure gauge should be within the range of 1 to 2 times the initial differential pressure.
For example, if the initial pressure difference is 10Pa, then the normal working pressure difference range is 10 to 20Pa. If it exceeds this range, be vigilant for abnormalities.
Judgment of reading stability
When the air shower system is operating stably, the pointer should be stable without severe fluctuations or frequent jumps.
If the pointer keeps fluctuating, it is necessary to check whether the pressure guiding pipe is leaking, whether the fan is operating stably and whether the filter is loose.
Iii. Judgment and Correspondence of Abnormal Readings
| Abnormal phenomenon | Reading characteristics | Judgment of normalcy | Possible reasons |
| The reading is 0 or close to 0 | When the fan is running, the pointer still stops at zero | Abnormal | The pressure guiding pipe has fallen off or is leaking. The internal damage of the differential pressure gauge; The high-efficiency filter is severely damaged or not installed |
| The reading is too low | Much lower than the initial pressure difference (such as less than 50% of the initial value) | Abnormal | The high-efficiency filter is not sealed tightly. The pressure guiding pipe is connected in reverse. Excessive clogging of the nozzle leads to a reduction in airflow |
| The reading is too high | More than twice the initial pressure difference, or reaching over 25Pa | Abnormal | The high-efficiency filter is clogged. The primary filter was not cleaned in time, resulting in insufficient air volume of the fan |
| The reading fluctuates greatly. | The pointer jumps back and forth without a stable value | Abnormal | The pressure guiding pipe is leaking. The fan is operating unstably. The door body was not closed tightly, causing the airflow to be disordered |
Iv. Key Points to Note
The differential pressure gauge judgment should be made when the air shower system is operating stably. Readings taken when the door is not fully closed or the fan has just started are invalid.
After each cleaning or filter replacement, the initial pressure difference needs to be re-recorded as the benchmark for subsequent judgment.
If the differential pressure gauge malfunctions and cannot be repaired, a differential pressure gauge of the same model and range should be replaced in a timely manner to ensure accurate monitoring.
Establish a record ledger for the readings of the differential pressure gauge, and record the operating differential pressure every day to facilitate trend analysis and early prediction of filter clogging.
