How much do you know about fire equipment pressure switch?

01. Working principle of pressure switch

After the alarm valve is opened, the alarm pipeline is filled with water, and the pressure switch is connected with the electrical contact after being affected by the water pressure, and outputs the signal of opening the alarm valve and starting the water supply pump. When the alarm valve is closed, the electrical contact is disconnected.

02. Pressure switch setting requirements

1. The pressure switch is installed on the system pipe network or the alarm pipe after the outlet of the alarm valve delay device. The automatic sprinkler system shall adopt a pressure switch to control the fire pump and the pressure regulator pump, and shall be able to adjust the pressure of the start and stop pressure regulator pump.

2. The water flow alarm device of the deluge system and the fire separation water curtain system should adopt the pressure switch.

03. Pressure switch inspection requirements

1. The nameplate shall be clear and marked with safe operation instructions and product instructions.

2. Each component shall not have loose mechanism, obvious processing defects, and the surface shall not have obvious rust, coating peeling, foaming, burr and other defects.

3. Test the action performance of the pressure switch, open the pressure switch, connect its normally open or normally closed contacts with a multimeter, and make the pressure switch act, and check whether the normally open or normally closed contacts of the pressure switch can be reliably turned on and off.

04. Pressure switch installation requirements

1. The pressure switch shall be vertically installed on the pipeline leading to the hydraulic alarm bell, and shall not be disassembled or modified during installation.

2. Install the pressure control device on the pipe network according to the fire protection design document or the installation drawing provided by the manufacturer.

3. The outgoing line of the pressure switch shall be locked with waterproof casing, and technical inspection shall be carried out by observation and inspection.

05. Pressure switch interlocking and linkage pump starting

1. Chain pump start

1) The fire pump in the fire hydrant system shall be directly started by the pressure switch set on the main water outlet pipe of the fire pump, the flow switch on the outlet pipe of the high fire water tank, or the pressure switch of the alarm valve. The signal of the pressure switch to start the fire pump shall not be affected by the automatic or manual state of the linkage controller. When the pump control cabinet is in the manual state, the pump start signal sent by the pressure switch will not directly start the fire pump.

2) The regulator pump shall be controlled by the automatic start-stop pump pressure switch or pressure transmitter set on the fire water supply network or pneumatic water tank.

3) In the automatic sprinkler system, the action signal of the pressure switch is used as the chain trigger signal to start the spray pump.

2. Linkage pump start-up (Illustration of Code for Design of Automatic Fire Alarm System)

1) The action signal of the pressure switch of the alarm valve of the wet, dry, deluge and water curtain system and the alarm signal of any fire detector or manual alarm button in the protection area of the alarm valve are used as the linkage control signal to start the fire pump.

2) When the water curtain system is used for fire shutter protection and fire separation, the action signal of the pressure switch of the alarm valve and the alarm signal of any fire detector or manual alarm button in the protection area of the alarm valve are used as the linkage control signal to start the fire pump.

06, pressure switch other

1. The rated working pressure of the pressure switch shall not be less than 1.2MPa.

2. The pressure switch is usually set on the main pipeline of the fire pump room or on the alarm valve, and the flow switch is usually set on the outlet pipe of the high-level fire water tank.

3. Automatic sprinkler system, pressure switch according to the actual installation of the number of full test its control function.

4. The water flow alarm device of deluge system and fire separation water curtain should adopt pressure switch. The deluge system and water curtain system adopt open nozzle. There is no water in the pipeline after the outlet of the alarm valve at ordinary times. In the pipeline filling stage after the system is started, the flow rate of water in the pipeline is relatively fast, which is easy to damage the water flow indicator. Therefore, the pressure switch is better.

5. The start and stop of the pressure stabilizing pump requires reliable automatic control. Therefore, the fire pressure switch is required to be used, and it is required to adjust the start and stop pressure of the pressure stabilizing pump according to the working pressure of the nozzle at the most unfavorable point.

6. The foam-water deluge system shall be equipped with deluge valve and hydraulic alarm bell, and pressure switch shall be set on the outlet pipeline of each deluge valve, but the single-zone system with less than 10 nozzles may not be equipped with deluge valve and pressure switch.

07, Knowledge Expansion-Pressure Switch

1. Classification

2. Preparation method

ZSJY1.2KY means pre-acting device, adjustable, automatic sprinkler system pressure switch model with rated working pressure of 1.2MPa.

3. Strength requirements

The hydraulic pressure strength test shall be carried out according to the specified method. The test pressure shall be 1.5 times of the working pressure and kept for 5min. The pressure switch shall be free of damage and leakage. The action test shall be carried out after the test, and the results shall meet the specified requirements.

4. Strength test

Install the pressure switch on the test equipment according to its normal working position, then slowly increase the pressure, increase the pressure to 1.5 times of the rated working pressure within 5s ~ 10s, keep it for 5min, check whether there is leakage during the pressure maintenance period, remove the pressure and check whether the mechanical structure is damaged, and the result shall meet the requirements; then carry out the action test according to the regulations, and the test result shall meet the requirements.