Alarm valve test displacement-Liu Ke

Alarm valve test displacement
Liu Ke
1. “Design Specification for Automatic Sprinkler” GB50084-2017 6.2.1 The automatic sprinkler system shall be provided with an alarm valve group. Closed systems protecting building components such as indoor steel roof trusses shall be provided with independent alarm valve groups. The water curtain system shall be provided with an independent alarm valve group or a temperature and rain alarm valve. 6.2.4 The sprinkler nozzles for the highest and lowest water supply of each alarm valve group shall not have a height difference greater than 50m. 6.2.5 The inlet of the solenoid valve of the rain alarm valve group shall be provided with a filter. In the rain system of the rain alarm valve set in parallel, the inlet of the rain alarm valve control chamber shall be provided with a check valve. 6.2.6 The alarm valve group should be located in a safe and easy-to-operate location. The height of the alarm valve from the ground is 1.2m. Drainage facilities shall be provided at the location where the alarm valve group is installed. 6.2.7 The control valve connected to the inlet and outlet of the alarm valve shall be a signal valve. When a signal valve is not used, the control valve should be provided with a lock to lock the valve position. 6.2.6 The installation height of the alarm valve specified in this section is for the convenience of construction, testing and maintenance. When the system is started and function tested, the alarm valve group will discharge a certain amount of water, so it is required to set up adequate drainage facilities during the design. Although this article stipulates that the alarm valve group will discharge a certain amount of water, it does not specify the displacement.
2. National standard GB5135.2-2003 “Automatic sprinkler system” Part 2: Wet alarm valve, retarder, hydraulic alarm bell definition of the wet alarm valve: only allow water to flow into the wet fire extinguishing system and at the specified pressure A single valve that drives the alarm of the supporting components under the flow. It can be seen that the wet alarm valve is a one-way valve that only allows water to be filled into the wet fire extinguishing system and can drive the supporting components to alarm under the specified pressure and flow rate. Function one: In the dry system, pre-action system, rain system, the alarm valve group automatically controls the normal water supply not to enter the pipe network, and to ensure that the water does not flow backward in the wet system. Function two: Automatic alarm to start the pump. Once the sprinkler sprays water, the hydraulic alarm bell sounds an alarm, and the pressure switch gives an instruction to start the fire pump. 4.4.1.1 The valve body shall be provided with a water outlet. The nominal diameter of the water outlet shall not be less than 20mm. 4.4.1.5 The nominal diameter of the water inlet of the hydraulic bell shall not be less than 20mm, and the area of ​​the drainage hole shall not be less than 50 times the area of ​​the nozzle. 4.9.1 The wet alarm valve shall be tested in accordance with the provisions of 5.7. At a flow velocity of 4.5m / S, the hydraulic friction shall not be greater than 0.04Mpa. When the hydraulic friction is greater than 0.02MPa and less than 0.04MPa, it shall be on the valve body and It is noted in the operating instructions that the hydraulic friction is less than or equal to 0.02 MPa, and no need to be marked. 4.10.1 The wet alarm valve is assembled and tested in accordance with the provisions of 5.8.2.1. When the inlet pressure is 0.14MPa and the system side water discharge is 15L / min, neither the pressure switch nor the hydraulic alarm bell should issue an alarm signal. The 15L / min here is 0.9T / h. The water supply pressure is 0.14MPa, 0.70MPa, 1.20MPa, 1.60Mpa, and the corresponding water displacement on the system side is 60L / S, 80L / min, 170L / min, 170L / min ( (Applicable to wet alarm valves with a rated working pressure greater than or equal to 1.60Mpa), pressure switches and hydraulic bell regulations shall issue alarm signals. After the water discharge on the system side is stopped, the wet alarm valve no longer flows to the pressure switch and the hydraulic alarm bell. The 170L / min here is 10.188T / h. It can be seen that the drainage pump flow rate between the alarm valves is above 10T / h. The alarm flow rate of the assembled wet alarm valve measured under the above pressure should not be lower than the alarm flow rate announced by the production unit. The delay time of the delay device, the delay device should be able to drain water automatically, and the maximum draining time should not be greater than 5min. This item is only for the test valve leakage of the alarm valve group equipment, not the actual project test leakage, which is the leakage under the test device.
3. “Code for Construction and Acceptance of Automatic Sprinkler System” GB50261-2017 5.3.1 The installation of the alarm valve group shall be performed after the pressure test and flushing of the water supply pipe network are qualified. During installation, the water source control valve and alarm valve should be installed first, and then the auxiliary valve of the alarm valve should be connected. The connection of the water source control valve, alarm valve and water distribution main pipe should make the water flow direction consistent. The installation position of the alarm valve group should meet the design requirements; when there is no design requirement, the alarm valve group should be installed in an obvious position convenient for operation, and the height from the indoor floor should be 1.2m; The distance between the front and the wall should not be less than 1.2m; the distance between the protruding parts of the alarm valve group should not be less than 0.5m. There should be drainage facilities on the indoor floor where the alarm valve group is installed. 7.2.5 The alarm valve debugging should meet the following requirements: 1 During the commissioning of the wet alarm valve, discharge water at the water test device. When the inlet pressure of the wet alarm valve is greater than O.14MPa and the discharge flow is greater than 1L / s, the alarm valve shall be activated in time. ; The hydraulic alarm bell with a delay device should emit an alarm bell within 5 to 90s, and the hydraulic alarm bell without a delay device should emit an alarm bell within 15s; the pressure switch should act in time and provide a feedback signal. Inspection quantity: all inspections. Inspection method: use pressure gauge, flow meter, stopwatch and observation inspection.
4. “Technical Specifications for Fire Water Supply and Fire Hydrant System” GB50261-2017 Article 9.3.1 Special test drainage facilities shall be provided at the test facilities of fire water supply systems, and the diameter of drainage pipes shall comply with the following requirements: The diameter of the drain riser at the end of the system water test device should be determined according to the discharge of the end test device and should not be less than DN75; 2 the drain riser at the alarm valve should be DN100; 3 the pressure test drainage at the pressure reducing valve The diameter of the pipeline should be determined according to the flow of the pressure reducing valve, but it should not be less than DN100. The ground drainage facility can be a drainage ditch or a floor drain. The corresponding drainage capacities of DN50 \ DN75 \ DN100 \ DN150 are 1.0L / S, 1.8L / S, 3.8L / S, 10.0L / S. The drainage riser at the valve should be DN100, and the nominal diameter of the pipe for draining the pressure reducing valve should not be smaller than the nominal diameter of the pressure reducing valve. Drainage at the alarm valve should be provided with a special drainage pipe for drainage. Ground drainage at the alarm valve can be shared with other domestic drainage facilities. For drainage facilities at the alarm valve group, you can refer to the method of draining water at the pressure reducing valve, and set up special drainage risers and drainage funnels. If the alarm valve group is set in the pump room, the fire drainage capacity of the fire pump should be considered at the same time. The drainage capacity is determined according to the flow of the water inlet pipe of the fire pool, because the municipal water inlet pipe entering the fire pool will be caused by the failure of the water level control float valve A large amount of water enters the fire pump room through the overflow pipe, and the v = 1.5m / s flow meter can be used to control the diameter of the pipe to determine the water intake of the fire pool. DN100, the flow is 11.775L / S = 42.39T / h; DN150, the flow is 26.49L / S = 95.36T / h. The test drainage of the fire-fighting pool should be discharged into the fire-fighting pool for recycling. The test drainage can be considered according to the operation flow of the fire pump in 5 minutes.
5. There are three places where the water leaks on the alarm valve group: 5.1 The drain port on the valve body. The national standard GB5135.2 states that the valve body should be set with a water outlet of not less than 20mm. 》 P8 and P10 provide two installation methods, one with a diameter of DN50 and the other with a diameter of DN25. 5.2 Delay (a volumetric device to reduce false alarms due to pressure fluctuations in the water source) Water at the flow plate, the diameter is DN20. 5.3 Drainage at the hydraulic alarm bell, the diameter is DN20. When debugging the wet alarm valve, drain the water at the test device. When it is greater than 1L / s, the alarm valve should be started in time; it is assumed that the water discharge valve is fully opened in the wait state. Because the height difference of the nozzles controlled by each alarm valve is not greater than 50 meters, the static pressure at the water discharge valve is 50 meters. DN50, the flow here is 6.76L / S; if the pipe diameter is DN25, the flow is 1.10L / S. At this time, it enters the second state. The alarm valve is opened due to the pressure difference. At this time, the drain valve receives the net pressure from the roof water tank. If the building is a 99.9-meter public building, the flow is 7.50L / S and 1.16L / S, plus the water leakage at the hydraulic alarm and retarder, is 9.82L / S and 3.48L / S. In the third state, the fire pump is started, and the water consumption of the sprinkler head is supplied by the fire pump. At this time, the water leakage is basically the same as the second state. It can be seen that different buildings, different systems, and different discharge pipe diameters are different. When there are multiple alarm groups between the alarm valves, the test water is generally one after the test is completed. If the total opening and drainage volume is quite large, consider an alarm valve to discharge water and the flow rate also reaches 10L / S. The drainage riser at the place should be DN100, and the maximum drainage capacity of the ventilated riser at DN100 is 4L / s. The second installation method in the map set adopted by the specification, the drain valve on the valve body is considered according to DN25> DN20, and DN100 Drainage pipe, 4L / S> 3.48L / S. In practice, the amount of water leakage for different buildings, different systems, or different discharge valve pipe diameters may be different, which should be based on actual conditions and treated differently.
References: 1. “Specifications for Automatic Water Spray Design” GB50084-2017
2. GB5135.2-2003 “Sprinkler system” Part 2: Wet alarm valve, retarder, hydraulic alarm bell
3. “Code for Construction and Acceptance of Automatic Sprinkler System” GB50261-2017
4. “Technical Specifications for Fire Water Supply and Fire Hydrant System” GB50261-2017

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