What Is a Positive Pressure Damper?
A positive pressure damper, also known as a differential pressure damper, relief damper, or barometric damper, is a device that regulates the internal pressure of a clean room to maintain positive pressure in the clean room.
By adjusting the differential pressure between the inside and the outside of the room, the positive pressure damper makes it possible to maintain a constant positive pressure inside a clean room.
Applications of Positive Pressure Damper
Positive pressure dampers are mainly installed in clean rooms to maintain a positive pressure inside the clean room that is one degree higher than the pressure outside the room.
They are also used in operating rooms.
Positive pressure dampers keep the room pressure higher than that outside the room, venting out only the amount of pressure that is higher than the specified value and closing the damper when outside pressure is applied to keep the room clean at all times.
Principle of Positive Pressure Damper
Positive pressure dampers are installed in ordinary clean rooms because it is necessary to keep the room at a positive pressure to prevent dust from entering from the outside.
One of the four principles for maintaining air cleanliness above a certain level is to “prevent the entry of contaminated air from the outside,” and for this purpose, the air inside the room must be kept at positive pressure (high pressure relative to the air outside the room).
On the other hand, if the pressure inside the room is too high compared to outside the room, it may cause adverse effects such as difficulty in opening and closing doors when entering and leaving the room.
Therefore, the opening door of the positive pressure damper opens and closes from time to time in response to the pressure difference with the air outside the room, making it possible to keep the air inside a clean room at a constant positive pressure.
Depending on the installation method, it is also possible to make the negative room pressure in the opposite direction.
In a clean room environment with strong pressure, the positive pressure damper may open and close frequently.
As a countermeasure, a weight can be attached to the back of the positive pressure damper’s open door to adjust the degree of opening.
Incidentally, the cleanliness of the air in a clean room is affected by the temperature, humidity, and cleanliness of the room, as well as internal heat generation, personnel in the room, local exhaust, and other factors that affect the capacity of the clean room air conditioning system.
There is also a damper with a fireproof shutter.
These dampers with fire shutters have a built-in thermal fuse that automatically closes the blades of the opening when the temperature rises above a certain level (72°C).
This allows the airflow between the damper and the point of fire to be blocked, preventing the spread of fire and the filling of toxic gases.
Variations for different applications are also available, such as X-ray protective types.