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How to effectively control differential pressure in cleanrooms
How to effectively control differential pressure in cleanroomsIn simple terms, the basic principle of effective control of differential pressure in clean rooms is to control the air supply, return, and exhaust air volumes, so that a certain positive pressure can be maintained when the amount of air fed into the clean room is greater than the return and exhaust air volumes.At this point, the difference between the static pressure inside and outside the room is equal to the difference between the amount of air that leaks out through the inaccessible parts of the envelope and the amount of air that enters and leaves the room mechanically. The main problem with the difficulty of maintaining the differential pressure is that the mechanical air supply and discharge volumes are constantly changing and are not stable. Especially for clean systems, filters that accumulate dust are more likely to cause an increase in the resistance of the fresh air and air supply ducts, thus affecting the air volume. At the same time, the air exhaust equipment can be turned on and off at times, which can easily lead to changes in the air exhaust volume. At this time, the system is also affected by changes in thermal and wind pressure in the adjacent parts of the building and outdoors, resulting in a certain pressure difference in the whole room. In response to the above problems, we recommend that the value of the pressure difference for the clean room needs to be regularly checked, and in turn to the new, supply, return, and exhaust air pathway valve to make the appropriate adjustments, then the next specific look at the control measures to maintain the pressure difference! 1. The so-called return air outlet control means that through the return air outlet on the adjustable grille or damping, the layer changes the resistance, to adjust the return air volume, to achieve the purpose of pressure control, which is a simple control method, characterized by a very simple structure, economical and practical. Because the adjustment of the grille is very convenient, and not easy to close, but also on the direction of airflow will have a certain impact. 2. There is also a residual pressure valve control method which is also very good, simply adjusting the balance pressure block on the residual pressure valve by manual or automatic methods, to change the valve opening of the pressure valve and realize the pressure change in the room. It is also important to note that when using this measure it is important to maintain sufficient residual positive pressure values in the clean room. 3. Adjusting the return air valve and the exhaust air valve is based on the pressure value in the testing room, and this time adjusting the electric valve on the return air duct or changing the return air volume are ways to control the pressure value in the clean room. 4. The next option is to detect the pressure in the room using a differential pressure transmitter and subsequently adjust the fresh air volume. |
