What is the reason for the increase in pressure difference of high-efficiency filter?

The differential pressure gauge reading is higher than usual, which in itself does not indicate the problem.

The pressure difference is a comprehensive reflection of air volume and resistance. Changes in air volume, dust accumulation in the filter element, or problems with the measurement pipeline may cause the reading to rise. Before directly replacing the filter element, look at these variables separately to avoid replacing things you shouldn't.

First confirm whether the working conditions have changed

The prerequisite for comparing differential pressure data is that the two readings were obtained under the same working conditions.

Increases in fan speed, changes in air valve opening, and changes in the status of other filter sections in the system will all affect the pressure difference at the end filter. If the fan gear or damper has been adjusted recently, the change in pressure difference may be just the result of changes in operating conditions, not a problem with the filter element itself.

It is recommended to compare this reading with the initial record under the same air volume and the same operating conditions. If possible, record the fan gear, air volume and pressure difference at the same time. Looking at the three data together can explain the situation better than looking at the pressure difference alone. For matching For the FFU fan filter unit system, unit gear change is a common cause, and this should be confirmed first when troubleshooting.

Check the system in order

After confirming that the working conditions are consistent, check further.

Differential pressure tapping port and pressure guide tube : This is a link that is easily overlooked. If the pressure port is blocked, the pressure tube is bent or dust accumulates, the reading will deviate from the actual value. During inspection, the status of the differential pressure gauge at other locations in the same system can be compared.

Filter surface : Check whether the filter material is damp and has abnormal dust accumulation. The resistance of the filter material may increase after it gets damp. This situation is more common in seasons with large humidity fluctuations. involving Products of different grades of HEPA/ULPA air filters may have different performances after getting wet. When checking, judge according to the corresponding material characteristics.

Pre-filter : The maintenance status of the primary and intermediate filters will affect the terminal load. If the front stage fails or has not been replaced for a long time, the dust accumulation rate of the final filter element will accelerate.

Fan and control status : Confirm that the fan is operating normally and the controller output is stable. Abnormal communication status of a certain unit in the group control system may also cause the operating gear to change.

Use trends instead of single judgments

A high reading doesn't mean much. The trend formed by continuous recording can better reflect the actual situation.

The pressure difference of a HEPA continues to rise under constant air volume, and the air supply margin gradually decreases. The dust accumulation speed can be judged based on the maintenance records, and a replacement plan can be arranged accordingly. If the pressure difference jumps on the day when the fan speed is increased, the influence of the change in air volume should be eliminated first, and then check whether the filter material is damp or whether the inlet dust has increased.

When the final resistance agreed upon by the project is reached, or the on-site leak detection fails, arrangements will be made according to project requirements. Don’t decide to replace based on just one reading , as this can easily lead to waste and may mask the real cause. Device-side applications such as In the EFU equipment-end fan filter unit , replacement of the internal filter element often involves equipment shutdown, and it is necessary to combine trend data when making judgments.

Develop processing and retest records

After the processing is completed, the pressure difference, air volume, operating time and on-site phenomena are recorded in the same account.

The recorded content should include: readings before treatment, treatment measures, readings after treatment, and retest date. The purpose of this set of records is that the next time a similar situation occurs, it can be referenced to determine whether the same type of problem occurs repeatedly or whether it is a new situation.

If the pressure difference rises too fast multiple times at the same location, in addition to dealing with the terminal filter element, you should also review the front-stage filtration configuration and on-site pollution sources. Troubleshooting this type of systemic problem is two different things from replacing the filter element once.

About Aili Industrial’s pressure difference investigation cooperation

Aili Industrial can assist in checking the filter element resistance, fan operating point and spare parts specifications. filter with FFU fan filter unit、The fan filter unit at the EFU equipment end is matched in the same manufacturing system. The filter element resistance and fan working point can be confirmed together during the planning stage to facilitate comparison and judgment during operation.

Provides initial pressure difference, current air volume and operation records, which can help troubleshoot equipment problems in a more targeted manner. The specific handling method shall be subject to on-site inspection results and project maintenance requirements.