Do I need to replace the fan when replacing the original H13 with H14?

This is probably the most frequently asked question during filter retrofit projects. The answer is not complicated, but it requires some calculation.

The resistance of H14 is usually higher than that of H13 of the same size. The resistance that the fan has to overcome increases and the working point will move. Whether it will move out of the acceptable range depends on how much fan margin is left in the original system. If the margin is enough, just replace the filter element; if the margin is not enough, just changing the filter element will not reach the target air volume, and then you need to turn on the fan.

So the question is not 'should the fan be replaced?', but 'where will the existing fan's working point fall under the new resistance?'

First test the actual working point of the original system

Before making the renovation, check the current situation clearly. Many people skip this step.

The data that needs to be recorded includes: the current actual air volume or surface wind speed, the fan operating gear or frequency, the current pressure difference of the filter, and the resistance of other links in the system.

There is a common pitfall here: the old H13 has been running for a period of time, and the pressure difference measured on site is the resistance after dust accumulation, not the initial resistance of the new filter element. Comparing this number with the factory initial resistance of the new H14, the benchmark is inconsistent and the calculated conclusion is unreliable.

The correct approach is to consider the dust accumulation state of the old filter element and the initial state of the new filter element separately to obtain comparable data.

Candidate filter elements should be compared under the same air volume

After selecting the H14 candidate product, obtain the resistance data of the product at the target air volume from the supplier.

When comparing, the new and old models should be placed under the same design air volume, rather than looking at the labeled values ​​of each. If the size or effective filtration area of ​​two products is different, the difference in resistance cannot be directly attributed to the grade and needs to be considered together with the structure.

After obtaining the new resistance data, compare the fan performance curve to find a new operating point. The judgment criteria are: whether this working point can operate stably at the target air volume, and how much margin the fan still has when the filter element accumulates dust to the final resistance.

Under what circumstances do you not need to replace the fan?

If these two conditions are met, there is usually no need to replace the fan:

The new working point is still within the range corresponding to the target air volume. After replacing H14, the air volume has decreased, but it is still within the allowable design range and can meet the face wind speed requirements of the target area.

After taking into account the rise in resistance in the later period, the margin is still sufficient. Calculating the initial resistance is only the first step. The resistance will rise after the filter element has been running for a period of time. At this time, the fan must be able to maintain the basic air supply capacity.

In this case, just replace the filter element and re-adjust the gear. The controller parameters may need to be adjusted accordingly.

Under what circumstances should the fan or other links be moved?

If the calculation finds that the new working point has deviated from the target air volume, and the adjustment gear cannot make up for it, it means that the fan margin is insufficient. There are several ways to deal with it:

Replace the fan. Choose a model with higher static pressure, but pay attention to the installation space, power supply conditions and control compatibility of the equipment or box.

Adjust filter element configuration. Without changing the grade, a structure with a larger effective filtration area is selected to reduce resistance at the same air volume.

Optimize air ducts. Check the air inlets, air outlets and internal structures for additional resistance that could be cut. This part of the improvement often does not require replacement of parts, but requires the cooperation of the equipment.

Reevaluate goals. If the system conditions determine that the H14 cannot achieve the original air volume in this space, it may be necessary to discuss with the process party whether the target area or face speed requirements need to be adjusted.

How to choose among these paths depends on the actual constraints of the project. For matching In the FFU fan filter unit system, the air duct and fan are integrated together, and the room for adjustment is relatively large; while The EFU equipment-side fan filter unit is limited by equipment space, so there are fewer options available.

The installation space and sealing should also be checked together

Grade upgrades are often accompanied by changes in the thickness or structure of the filter element. Even if the length and width are the same, they may interfere with the original box, diffuser plate or access opening after installation.

For the position of the liquid tank seal, check whether the tank size of the new filter element matches the knife edge of the original box. For details, please refer to the relevant interface instructions. The distribution of the pressing parts and the compression state of the gasket must also be re-confirmed. These factors are as important as fan calculations, and assembly feasibility cannot be ignored because of focus on air volume.

Trial installation first and then batch production

For renovation projects, it is recommended to first conduct a trial installation in a representative location.

Install the H14 filter element, run it to a stable state, measure the actual air volume and surface wind speed, and compare the original state data. At the same time, perform installation leak detection according to project requirements to confirm that the interface seal is normal.

After the test installation results confirm that the solution is feasible, batch replacement will be carried out. In this way, the calculation results can be reflected on the actual measured data, so as to avoid discovering problems after batch replacement.

For those involving For HEPA/ULPA air filter grade changes, it is recommended that the test data of the new and old products be filed together so that the inspection data can be documented.

About Aili Industrial’s transformation package

Aili Industrial can help identify alternatives by combining the old filter element, installation frame and fan parameters. filter with FFU fan filter unit、The EFU equipment-end fan filter unit is matched in the same manufacturing system, and the filter element resistance and fan operating point can be calculated together at the planning stage.

For the project of upgrading H13 to H14, it is recommended to provide the original fan model, operating parameters, old filter element specifications and target air volume, so as to determine whether the fan or other links need to be adjusted. The specific plan shall be subject to trial installation testing and project confirmation documents.