Mainly depends on whether it is opened or closed in the actual process. Supply air to see if there is air passing through, or check the signal display in the fire control room. Generally speaking, those installed on air conditioning and ventilation pipes below 70 degrees are normally open; Installed on the smoke exhaust duct, called a smoke exhaust fire damper, normally open at 280 degrees Celsius. If the smoke exhaust fan is also used for regular ventilation, it is normally open; if it is the opposite, it is normally closed.
How to distinguish between normally open and normally closed fire dampers?
Fire dampers are installed on the supply and return air ducts of ventilation and air conditioning systems, usually in an open state. In case of fire, they are closed when the flue gas temperature in the duct reaches 70 ℃, and can meet the requirements for smoke leakage and fire resistance integrity within a certain period of time, playing a role in smoke isolation and fire resistance. Fire dampers are generally composed of components such as valve bodies, blades, actuators, and temperature sensors.
Fire dampers installed on air conditioning and ventilation pipes are normally open at temperatures below 70 degrees Celsius. If the fire damper is installed on the smoke exhaust pipeline, it is called a smoke exhaust fire damper, and it is also called a normally open valve at 280 degrees Celsius. The difference lies in whether it is opened or closed in the actual process. One is to supply air to see if there is air passing through, or to see the signal display in the fire control room.
The 280 degree smoke exhaust and fire damper has a normally open position, which often appears at the exit of the kitchen smoke exhaust duct in high-rise buildings. The smoke exhaust and ventilation combined system has both normally open and normally closed electric fire dampers. The 70 degree fire damper has normally open and normally closed options. The 280 degree smoke exhaust fire damper also has normally open and normally closed options, depending on the usage situation.