What are FFU and BFU?

In clean rooms, dust-free workshops, pharmaceutical factories, electronics factories and other places where air cleanliness is required, FFU and BFU are two common terminal air supply purification equipment.

FFU (Fan Filter Unit) , the full name in Chinese is fan filter unit, is a modular terminal air supply device with its own power and filtering function. FFU integrates a fan with a high-efficiency (HEPA) or ultra-high-efficiency (ULPA) filter, sucks in air from the top, filters it through the high-efficiency filter, and sends it out from the air outlet surface at a uniform wind speed. FFU can be connected and used in a modular manner, and is widely used in clean rooms, clean workbench, clean production lines, assembled clean rooms and local level 100 applications.

BFU (Blower Filter Unit / Blower Fan Unit) , which can be called blower filter unit or fan filter unit in Chinese, is a ceiling-mounted unit equipped with a built-in fan. It is also used in turbulent and laminar flow clean rooms. BFU and FFU are similar in basic functions - they both use fans to drive air through high-efficiency filters to deliver clean air to the clean room. However, there are some differences between the two in terms of structural design, filtering methods and applicable scenarios.

The core difference between FFU and BFU

1. Different filtering methods

This is one of the more commonly mentioned differences between the two.

BFU usually uses baffle filtration technology - using baffles to separate the air volume, which is then filtered through filters. The FFU adopts an integrated filter design, integrating the filter and fan to form a complete filtration unit. In terms of filtration effect, the integrated filter design used by FFU is generally considered to perform better in high-cleanliness environments.

2. Different static pressure capabilities

This is one of the core differences between the two in engineering applications.

Standard FFU is usually installed on the ceiling, relies on the return air path of the room, and has a relatively low design static pressure. The design of BFU can withstand higher external static pressure than standard FFU, making it suitable for pipeline connections and applications that need to overcome higher resistance. BFU can be used in ducted air supply systems or pressurized plenum designs, functioning closer to local air handling devices.

3. Different installation and maintenance methods

FFU is usually installed on the keel frame of the clean room ceiling. When replacing the filter, workers generally need to lift the box down from the ceiling for operation.

BFU usually adopts a detachable design, and the filter can be removed and replaced directly from below without entering the ceiling space. For places with limited ceiling space or inconvenient ceiling operations, BFU's maintenance method is relatively convenient.

4. Different applicable scenarios

5. Different cost positioning

From the perspective of market positioning, BFU is seen as a more cost-effective option in some scenarios. BFU can be positioned as a simplified version of the basic FFU, retaining only the core fan and filtering functions. Some manufacturers also position BFU as an upgraded substitute for FFU and HEPA-BOX. Different manufacturers have different positioning and pricing strategies for BFU, and the selection needs to be evaluated based on specific product specifications.

How to choose FFU or BFU?

When selecting a model, it is recommended to make a comprehensive judgment from the following perspectives:

1. Look at the cleanliness level requirements

• For occasions with higher cleanliness requirements and a clean environment requiring ISO Class 5 (Class 100) and above, FFU is a more common choice.

• For low-level purification workshops with relatively low cleanliness requirements, BFU can be considered as an option.

2. Check the installation and maintenance conditions

• Where there is sufficient ceiling space and maintenance can be performed from above, FFU is easy to install.

• When the ceiling space is limited or you want to replace the filter from below, the BFU's detachable design has more advantages.

3. Look at the system design requirements

• For conventional clean room ceiling installations that rely on room return air, standard FFU can suffice.

• Where pipe connections, pressurized plenums or to overcome high system resistance are required, BFU can be considered

4. Look at the project budget

• Subject to cleanliness requirements, BFU may provide a more cost-effective option in some scenarios.

Overview of comparison between FFU and BFU

Aili Industry—Full industry chain FFU manufacturer

Aili Industrial has been deeply involved in the field of clean room equipment for nearly two decades. From fan winding, box processing to control system development, the entire industry chain independently manufactures FFU fan filter units. The products cover a full range of standard, ultra-thin, energy-saving (EC motor), group control, and stainless steel types, supporting full-dimensional customization in size, material, motor, control method, filtration level, etc., and adapting to the different cleaning needs of 13 major industries including semiconductors, panel displays, pharmaceuticals, food, and data centers.

If you need FFU selection suggestions or customized solutions, please contact the professional technical team of Aili Industry.