How to choose FFU fan filter unit?

1. Clarify the needs first: five questions before selection

Before choosing FFU, it is recommended to sort out the project requirements from the following questions:

• What is the target cleanliness level? Is it ISO Class 5 (Class 100), ISO Class 6 (Class 1,000), ISO Class 7 (Class 10,000), or ISO Class 8 (Class 100,000)?

• In which industry is it applied? Different scenarios such as semiconductors, panel displays, pharmaceuticals, food, and data centers have different requirements for materials, motors, and explosion protection.

• Is the installation space limited? Is the floor height sufficient? Can the suspended ceiling bear the weight of FFU?

• What are the requirements for energy consumption and noise? Are there energy saving targets and noise caps?

• What is the operation and maintenance method? Is it local manual adjustment, or do you want to achieve centralized control and remote monitoring?

2. Match FFU coverage according to cleanliness level

Different cleanliness levels have significantly different coverage requirements for FFU:

Why does level 100 need high coverage? Class 100 clean rooms rely on unidirectional flow (laminar flow) to ensure cleanliness, and the entire work area section requires uniform downward airflow. As long as there is a section of the ceiling that is not equipped with FFU, there will be no vertical airflow at that location, and particles will settle and accumulate there.

FFU quantity calculation formula : FFU quantity = (clean room area × target coverage) ÷ effective coverage area of ​​a single FFU.

For example, a chip factory has a 100㎡ clean room (ISO level 5) and uses 1.2m×0.6m FFU (effective area 0.65㎡/unit): theoretical quantity = (100×70%) ÷ 0.65 ≈ 108 units, and it is actually recommended to deploy 123 units (redundancy 15%).

3. Motor type: AC or EC?

The motor is the 'heart' of FFU, which directly determines air volume, stability, energy consumption and noise.

Selection suggestion : If the number of clean room FFU exceeds 20 and requires long-term 24-hour operation, the energy-saving advantage of EC motor FFU can recover the price difference with AC motor FFU within 1-2 years. In scenarios where the quantity is small and the frequency of use is low, initial investment in AC motor control can be given priority.

Based on a single FFU operating for 8,000 hours per year, the annual electricity bill for an EC motor is about 1,200 yuan and for an AC motor is about 1,800 yuan. A single FFU can save about 600 yuan per year. The energy-saving benefits are even more impressive when deployed on a large scale.

4. Filter grade: HEPA or ULPA?

The filtration system is the core of FFU and must first match the cleanliness level and process requirements.

• HEPA high-efficiency filter : filtration efficiency for 0.3μm particles ≥99.97% (H13) or 99.995% (H14), suitable for ISO 5-8 clean rooms.

• ULPA ultra-high efficiency filter : filtration efficiency for 0.12μm particles is ≥99.9995%, suitable for ISO 1-4 ultra-high cleanliness scenarios, such as semiconductor manufacturing.

Selection tip : Using H13 filters in ISO class 8 clean rooms will increase wind resistance and shorten service life. The higher the class, the better.

5. Air volume and static pressure: sufficient and stable?

Air volume and static pressure are the keys to matching the number of air changes in a clean room.

Standard FFU common specifications :

• 1200×600mm: Air volume is about 1000-1200m³/h

• 1200×1200mm: air volume about 2000m³/h

Air exchange rate reference :

• One hundred thousand level: 15-25 times/hour

• Level 10,000: 50-60 times/hour

• Thousand level: ≥100 times/hour

• Level 100: One-way flow is required, and the surface wind speed is 0.35-0.45m/s

Static pressure outside the machine : When the rated wind speed is 0.45m/s, the residual pressure is recommended to be ≥100Pa, and the high-resistance circuit is recommended to be ≥140Pa to ensure that the air can still flow stably even after the filter accumulates dust. When selecting the filter, you need to calculate the final resistance of the filter and select an FFU with a static pressure value greater than the final resistance (it is recommended to reserve a static pressure margin of more than 20%).

6. Box material and structure

The material of the box determines durability and resistance to deformation:

• Galvalume plate : cost-effective, rust-proof and lightweight, suitable for most conventional clean rooms

• Stainless steel 304/316 : corrosion-resistant, easy to clean, suitable for GMP clean workshops in pharmaceuticals, food, medical, etc.

• Plastic spraying of steel plate : beautiful surface treatment and certain anti-corrosion ability

Structurally , the box splicing should be tight, the static pressure chamber should be reasonably designed, and the air flow should be evenly distributed. The installation module is preferably 1200×600mm, which is suitable for mainstream clean room keels; ultra-thin models (≤180mm) are available if the floor height is limited.

7. Control mode: single control, centralized control or group control?

The control method of FFU directly affects daily management efficiency and energy saving potential:

• Single unit independent control : adjust the wind speed of a single FFU through the local knob or panel, suitable for small clean rooms or applications with a small amount of FFU

• Centralized control : A large number of FFUs are connected to the unified control platform through the host computer, and wind speed, start and stop can be set by zone, suitable for large-area electronics factories, pharmaceutical GMP workshops, etc.

• Remote monitoring : realize remote operation monitoring and alarm through the network, and can be connected with the building automatic control system

When a large number of FFUs are deployed in a clean room, the group control system can centrally manage multiple FFUs, greatly improving operation and maintenance efficiency.

8. Common misunderstandings in model selection

Misunderstanding 1: Only look at air volume and ignore static pressure matching. When selecting the filter, it is necessary to calculate the final resistance of the filter to ensure that the FFU static pressure value is greater than the final resistance (it is recommended to reserve more than 20% margin), otherwise the air volume will be significantly attenuated after the filter accumulates dust.

Misunderstanding 2: Blindly pursuing high coverage. Using 50% coverage in an ISO Class 7 workshop will double energy consumption and may disrupt airflow organization.

Misunderstanding 3: The higher the filter level, the better. The use of H13 filters in ISO class 8 clean rooms will increase wind resistance and shorten service life, so it should match actual needs.

Misunderstanding 4: Just compare prices. Low-priced FFU often use low-efficiency motors, thin boxes, and non-standard filters to reduce costs. This saves a small amount of money in the early stage. However, in the later stage, the electricity bill is high, replacement is frequent, and the cleanliness is not up to standard, and the total cost is higher.

Summary of selection steps

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.