Four elements of FFU fan design

- Nov 02, 2019-

First, the air volume and residual pressure

The parameters such as air volume, residual pressure, noise, and efficiency in the performance of FFU fans are interrelated and mutually constrained. Increasing a certain performance parameter will inevitably lower another part of the performance parameters. In general, the air volume of the FFU fan is expressed by the wind speed of the FFU fan section. According to the requirements, the wind speed of the section should be 0.5-0.45m/s, and the air volume of the 1175×575×350 FFU fan is about 900-1000m3/h. In order to ensure the normal use of the FFU fan, the rest of the pressure is 80-120Pa. Because the cold resistance of the double-row dry gauge is about 30-50Pa, the resistance of the return air interlayer and the return air clamp is also 20-40Pa, because the return air interlayer and the return air duct are covered with electricity, water, gas and exhaust air. The pipeline is also equipped with some auxiliary equipment. Therefore, the height of the return air interlayer should not be too small, and the width of the return air passage should not be too narrow.


Second, noise

Noise is one of the important technical indicators of FFU fans. In order to reduce the noise, many manufacturers have made great efforts, some research and improvement on the noise reduction structure of the tank flow, and some of them are larger and larger in the fluid mechanics of the fan impeller. effort. But the noise problem is still a research topic of FFU fans. Therefore, reducing the noise of the FFU is still the direction of efforts of various manufacturers, and is also a performance parameter that should be emphasized by people who design and use FFU fans. In the "clean factory design code GB50073-2001" clearly stipulates: "noise level (empty state) in the clean room, non-unidirectional flow clean room should not be greater than 60dB (A), unidirectional flow, mixed flow clean room should not be greater than 65dB(A)". When considering the superposition of multiple FFU noises, it is not easy to ensure that the noise meets the specification requirements. At present, personal blogs use the FFU mode of large-area unidirectional flow, mixed-flow clean room noise is generally more than 65dB (A) and up to 68-70dB (A).


Third, control FFU fan air supply mode

It can be divided into the wind speed control of the FFU fan air supply section and the control of the temperature and relative humidity of the clean room of the IIIV air supply mode.

1. FFU fan air supply section wind speed control, there are generally three kinds, the first is that the wind speed control requirements are not high, AC motors usually use manual multi-shift switch for speed control, this speed is not stepless but limited Secondly, the AC motor can adopt frequency conversion speed regulation, which can save energy, but the initial investment is very high; the third type is intelligent control with DC motor, which has energy-saving function, and can also be monitored and controlled by remote control.

2. When using the FFU fan air supply mode, the temperature and humidity of the clean room are controlled. FFU fan air supply is difficult to achieve. There is a requirement for different temperature and humidity conditions in a local area in a large-area clean room. If the temperature and humidity requirements of the local area are very strict, the part must be separately partitioned, and then an independent air conditioning system is set up for independent temperature and humidity control.


Fourth, maintenance management adopts FFU fan air supply mode

It is often not a single device but dozens, hundreds or even thousands of FFU fans are placed on the ceiling, thus bringing certain difficulties to maintenance management. Therefore, when selecting FFU fan products, it is necessary to consider the convenience of replacement of high-efficiency air filters and the reliability, stability and long life of the fans.