What should I check when upgrading from H14 to U15 or U16?

When upgrading, the most common problem is not 'choosing the wrong grade' but 'only changing the filter element'.

H14, U15, and U16 belong to different groups in the standard system, with different efficiency and penetration requirements. But after it is installed in the system, whether it can be used and the effect after use depends on a set of conditions. Replacing the filter element is only one step. Any missing step in the previous check and subsequent verification may cause problems.

First check whether the interface can be matched

This is the most basic step, but also the most easily skipped.

Frame size. The length, width and thickness should correspond to the installation frame. If the thickness of the upgraded filter element increases, it may affect the assembly and maintenance space.

Sealing method. Is it the gasket compression or the liquid tank seal? Does the upgraded filter element sealing structure match? The dimensions of the blade and tank body of the liquid tank seal must be checked item by item, not just the appearance.

fixed way. Whether the position, quantity and fastening method of the pressing parts are suitable for the outer frame structure of the new filter element.

Maintenance path. After the new filter element is installed, can it be taken out? Will the equipment cover, pipelines, and diffuser panels block the disassembly and assembly path? This is especially important in device-side applications.The internal space of the fan filter unit at the EFU equipment end is compact, and the available height is often determined during the equipment design stage. When upgrading, it is necessary to confirm whether the thickness of the new filter element is still within the allowable range.

Let’s also calculate the resistance and fan.

If H14 is replaced with U15 or U16, the resistance will usually rise. But how much the rise will be and whether the fan can withstand it can only be known after calculation.

Get the resistance data of the new filter element. What is the resistance of the new filter element at the target air volume? How different is it compared to the original H14? This data must be obtained from the supplier and cannot be inferred based on the grade.

Compare the fan curve. Put the initial resistance and final resistance of the new filter element into the total resistance of the system, and compare it with the fan performance curve to see where the operating point falls. If the operating point has deviated from the range corresponding to the target air volume, it means that the fan margin is insufficient.

Consider the final resistance condition. The resistance of the filter element will rise after running for a period of time. If the calculation is only based on the initial resistance, the air volume after installation is just enough, but it may not be enough after a few months of operation.

Supporting FFU fan filter unit system, the filter element and fan are in the same unit, so the calculation is relatively straightforward. For centralized air supply systems, the resistance of air ducts, air valves and other filter sections must be taken into account. For equipment-side applications such as EFU, the fan selection range is small, and more room needs to be left in calculations.

Sealing and leak detection conditions must be confirmed simultaneously

As the grade increases, so does the sensitivity to localized leaks.

The condition of the installation sealing surface. Is the installation frame deformed? Have the gaskets aged? Is the knife edge of the liquid tank intact? These should be checked before upgrading, and problems cannot be discovered after installing a new filter element.

Leak detection methods and instruments. The judgment limits of U15 and U16 are stricter than H14. Do the measuring ranges, aerosol conditions and scanning methods of the leak detection instruments used on site meet the new level of testing requirements? If the instrument is not sensitive enough, even if there is a leak, it may not be detected.

Testing standards must correspond. Different levels may invoke different judgment clauses. The procurement documents and acceptance plan should state what standards will be used for leak detection after the upgrade to avoid applying the H14 plan to U16. For the verification method of the sealing structure, please refer to the relevant instructions on the liquid tank seal.

System verification must be done after upgrade

Replacing the filter element does not mean the upgrade is complete.

Air volume and wind speed distribution. Measure the actual air supply volume and face air speed at the working gear to confirm that they are restored to the design range. If the air volume drops significantly, you need to go back and check whether the resistance calculation is accurate and whether the fan needs to be adjusted.

On-site leak detection. Scan the filter material surface and interface according to the project plan to confirm the sealing status. The upgraded leak detection records should be saved corresponding to the product number and installation location.

Area particle testing. Whether the particle concentration in the protected area meets the design requirements. This item does not have a one-to-one relationship with the filter element grade, and is also affected by air flow organization, pollution sources and operating conditions. involving Products of different grades of HEPA/ULPA air filters have the same verification methods, and the criteria are implemented according to corresponding standards.

Pre-upgrade data is retained. The original air volume, pressure difference, and leak detection records of H14 during operation are the benchmark for comparison after the upgrade. Without this set of data, it is impossible to judge what changes the upgrade has brought.

Project judgment example

A certain device is originally equipped with H14 and plans to upgrade it to U16.

During the inspection, it was found that the new filter element could be installed into the original installation frame, but the thickness was 5 mm thicker than the original filter element, causing slight interference when the access door was closed. Regarding the fan, the resistance of the new filter element at the target air volume is about 30% higher than that of the original H14. Calculated according to the fan curve, the operating point is close to the upper limit of the capacity.

In this case, directly replacing the filter element is not a suitable option. The processing direction may be: adjusting the access door structure or replacing a thinner structural solution; at the same time, evaluating whether the fan needs to be replaced, or whether to re-evaluate the target after accepting a moderate decrease in air volume.

The upgrade plan can only be decided after these conditions are confirmed. You cannot change the filter element first and then see the effect. involving For the selection conditions of ULPA ultra-high efficiency filters , please refer to the corresponding product information.

Selection and Acceptance Checklist

About Aili Industrial’s upgrade and transformation cooperation

The core of the calculation of grade upgrade is to look at the filter element, fan and installation conditions together.

Aili Industrial's manufacturing system covers filters, motors, fans, control systems and complete machine assembly, and can provide ULPA ultra-high efficiency filters and HEPA/ULPA products of different grades. filter with FFU fan filter unit、When the EFU equipment-side fan filter unit is matched in the same system, the filter element resistance and fan operating point can be calculated together at the planning stage, and the interface size and sealing structure can also be confirmed uniformly.

When enquiring, provide the original filter element specifications, fan parameters, installation space and target air volume, which will help determine whether the upgrade plan is feasible. The specific configuration is subject to the technical documents and test results confirmed by the project.