How does the FFU appearance size match the ceiling module?

FFU is installed on the clean ceiling, and the overall dimensions are not isolated numbers. It should be checked together with the ceiling modulus, supporting edge width, sealing position, and maintenance methods. Just because it can fit into the ceiling opening does not mean it is installed properly. If the supporting edge is too narrow, the sealing surface is misaligned, or there is insufficient air intake and maintenance space above, air leakage, vibration, or difficulty in replacing the filter may occur later.

The following will start from the following aspects: size definition, support sealing, installation and maintenance, and renovation of old ceilings.

Dimensional drawings need to distinguish between multiple benchmarks

Many projects only look at a 'nominal size', such as 1175×575, and think it can match. The actual installation involves multiple benchmarks: clear opening of the ceiling, equipment frame, supporting edge, filter size, and sealing surface location. These dimensions are defined differently in different ceiling systems and cannot be mixed.

For example, for FFUs with the same nominal module, the outer frame may be slightly smaller and rest on the keel by the supporting edge; or the outer frame may be flush with the opening and sealed by the side. If you place an order based on nominal dimensions only, you may find on site that the spacing between keels is incorrect, the supporting edges do not fit together, or the sealing strips are not pressed tightly.

If you are not clear about the difference between effective air outlet area and external area, you can see How should we look at the effective air outlet area of ​​FFU? , first distinguish the calculated caliber, and then check the installation dimensions.

The supporting position and sealing method must be confirmed at the same time

Different ceiling systems have different supporting and sealing positions. Common ones include: keel support, independent bracket support, side seal, top seal, etc. The width of the supporting edge, the compression amount of the sealing strip, and the pressing method will all affect the air leakage rate.

When replacing an old suspended ceiling with an FFU of the same nominal specification, if the width of the supporting edge changes, the support and sealing should be re-confirmed, and the old installation method should not be used directly. A loose seal can cause bypass leaks, allowing unfiltered air to enter the clean side. For seal inspection, please refer to How to read the test particle size in the filter efficiency report? Instructions on the difference between finished product and installation.

If you have questions about the relationship between filtration efficiency and site grade, you can see What is the difference between cleanliness level and filtration efficiency ? Avoid misdiagnosing sealing problems as filter problems.

Leave installation and replacement paths aside

Air inlet space, wiring space and filter replacement space are usually required above the FFU. The detachable FFU can replace the filter from below, while the FFU with top maintenance requires upper access. The two methods have different requirements for ceiling height and peripheral equipment.

Light fixtures, pipes, fire sprinklers, and structural beams should not obstruct maintenance. If ceiling space is limited, you can evaluate low-profile or side-access models, but you must check whether the air volume, static pressure, and filtration area meet the goals. Insufficient maintenance channels will increase subsequent expenditures. This is reflected in what later expenses will be increased due to insufficient maintenance channels . There is a more detailed analysis of

If the project is constructed in phases, please refer to What are the expansion conditions for using independent modules in clean systems? , unify the ceiling module, control address and installation benchmark in advance.

Equipment weight and ceiling load

The weight of the FFU includes the box, motor, fan and filter. The weight of different models and different filter configurations may vary greatly. The load-bearing and fixing methods of the ceiling should be checked before installation to avoid vibration or deformation after operation.

If the load-bearing capacity of the suspended ceiling is insufficient, separate supports or dispersed arrangements may be required. Lightweight models can reduce the load, but the air volume, static pressure and structural strength must also be checked. For the relationship between weight and vibration, please refer to How does a wafer inspection platform balance cleanliness and low vibration? , understand the vibration transmission path.

Matching of overall dimensions and air volume and static pressure

FFUs with similar dimensions may have different internal structures and filter areas, as well as actual air volume and static pressure. When selecting, you should not just look at the outer frame size, but also check the working point with filter, external static pressure and filter resistance.

If the nominal air volume is no-load data, it may drop significantly after being installed in the ceiling. For relevant judgments, please refer to Is FFU's nominal air volume tested with a filter? and What does FFU external static pressure mean? . The complete performance curve is available for reference Why should we look at the complete performance curve when selecting FFU?。

Filter selection should correspond to target particle size and actual resistance.The HEPA and ULPA filter pages have parameters for different levels of products. When selecting, check the efficiency of the specific model at the target air volume.

Interface coordination with group control and EFU

If multiple FFUs require partition duty and troubleshooting, they can be combined FFU group control system provides unified management. The locations of control cables and sensors should also be reserved on the ceiling plan.

For partial protection on the equipment side, please refer to EFU equipment end fan filter unit , room background air supply can be referred to FFU clean air supply products . The logic of division of labor between the two lies in The division of labor between device-side EFU and room FFU is explained in detail.

If the equipment cavity has special size requirements, please refer to How to plan clean air supply for closed equipment cavities? , first confirm the cavity boundary and air flow path, and then determine the installation interface of FFU or EFU.

Project judgment example

In a project, the old ceiling was replaced with FFU. The nominal dimensions were the same, but the supporting edge of the new model was narrower than that of the old model. After installation, local air leakage occurred, and particles on site were unstable. Investigation revealed that the sealing strip was not pressed against the keel. Adjustment method: Add a transition support frame and re-tighten the seal. The air leakage was resolved after replacement.

In another project, there are firefighting pipelines and structural beams above the suspended ceiling, and the original plan was to conduct top maintenance. During installation, it was discovered that the filter could not be replaced. Adjustment method: Switch to a detachable model and recheck the ceiling opening and supporting edge. After adjustment, the maintenance channel is retained, and there is no need to dismantle the ceiling to replace the filter.

These two situations illustrate that: FFU appearance dimensions match, not only the length and width, but also the support, sealing, weight and maintenance methods.

Key points for selection and acceptance inspection

Aili industrial equipment supporting support

Aili Industry covers motor manufacturing, independent research and development and production of fans, control system development, sheet metal processing, air filter manufacturing and complete machine assembly. For FFU ceiling matching projects, FFU, EFU, HEPA/ULPA filters, group control systems, air volume, static pressure, and installation interfaces can be uniformly checked to connect equipment configuration with on-site evaluation boundaries and reduce the disconnect between component parameters and complete machine operating conditions.

learn FFU clean air supply products；EFU equipment side fan filter unit；HEPA and ULPA filters；FFU group control system checks the installation space, operating conditions and filtered air supply configuration.