Generally, smoke and fire dampers are installed in the air supply pipeline and return air pipeline of the air conditioning system, and the smoke and fire dampers are interlocked with the supply and return fans, that is, only when the smoke and fire dampers are in the open state, the fans It is possible to start the rotation, and once the fire damper is closed, the fan will not start, and if the smoke and fire damper in the air duct automatically closes during the fan operation, the fan in the air conditioning system will automatically stop running.

For example, in the operation of an air-conditioning system using a temperature-sensitive fire damper, when the temperature of the air passing through the air duct exceeds the closing temperature of the fire damper (for example, over 70°C), the fusible element is disconnected and the tension spring is disengaged. The moving iron core hook in the transmission mechanism will automatically close the valve under the action of the rotating shaft hook, so as to prevent the airflow from passing through, and play the role of smoke and fire prevention. However, in actual use, although the temperature of the air passing through the smoke and fire protection does not exceed 70°C, due to some other reasons, the tension spring is disengaged from the temperature fusible parts, causing the smoke and fire dampers to automatically close. At this time, the normally closed contact of the intermediate relay (intermediate relay for fire alarm) connected in series in the fan control circuit is disconnected, and the fan in the running state will automatically stop at this time, and the fan in the stopped state cannot be started.

Therefore, in the air-conditioning system equipped with smoke and fire dampers on the supply air main pipe and the return air main pipe, under normal power supply and load conditions, there is no abnormality in the fuses and thermal relays in the main circuit of the fan power supply, and there is no over-temperature alarm signal. , When the fan in normal operation suddenly stops rotating, or the fan in the shutdown state cannot be started, it is generally caused by the automatic closing of the smoke and fire dampers. When this happens, a careful and careful inspection should be carried out, and only when it is confirmed that it is not caused by smoke or fire alarm, the smoke and fire dampers can be reset, so that the fan can continue to be put into operation.

Suzhou Pharma Machinery Co.,Ltd.

2022/09/07

Birkey