Pressure relief valve for emergency shut down valve and emergency valve set to open

Editor's note: The pressure relief valves, emergency shut-off valve and emergency valve is open and applications in recent years the development of valves, water supply has been building and fire circles, issues relating to its setting on the views of their own.



1 pressure relief valve



Pressure relief valve installed in the fire service pump outlet pipe, the normal shut down, the fire more than the pressure of water supply network settings automatically when turned on, water supply system in order to prevent damage due to overpressure.



Fire to the water distribution network of over-pressure was mainly due to the following reasons: ① design flow selected by the fire pump flow - lift curve is steep type, in a small flow of run-time (the initial self-test or fire) will appear overpressure; ② pumps due to a sudden it (such as power failure) stop transfer, delivery and did not take appropriate technical measures to stop pump water hammer caused by overpressure.



Pressure relief valve settings should pay attention to the location, caliber choice, pressure and the corresponding annex to configuration settings and so on.



① pressure relief valve may be located in the vicinity of the fire pump or water tank near the fire. Automatic sprinkler system design specifications "GBH84-1985 amendment to Article 10.3.3 of the支审稿requirements:" ... ... each pump control valve outlet pipe should be set up ... ... and, if necessary, pressure relief valve should be located. "Approval of the provision in the draft was changed to: "... ... when necessary, should be taken to control the pump outlet pressure for the measure." These measures which includes the pressure relief valve.



When the pressure relief valve installed in the outlet pipe when the fire pump can be located in a non-return valve before and after. Before a non-return valve located in a small flow of water running digestion caused by excess pressure, and after in a non-return valve (along the direction of flow) due to not only remove a small flow of water caused by running the overpressure, but also remove from the parked pump water hammer caused by excess pressure, even if the fire pump outlet pipe to stop the elimination of not taking other measures to pump water hammer (speed closed check valve, relief check valve closed, the buffer tank, etc.), will not cause harm and loss.



② There are two pressure relief valves caliber practice, a mains water supply with fire or with the Path 1, and the other is DN100 or DN150 using the pressure relief valve.



From the relief perspective, the greater the diameter of the pressure relief valve pressure relief sooner, the better. As shown in Figure 1, Q for the vent flow, large diameter pressure relief valve, Q value on big, RBC curve tend to the right, R and H curve curve intersection point M will be shifted to right, the pressure decreases. However, from the economic point of view, the larger caliber, higher prices, and more pressure relief valve, will inevitably increase the cost of project construction. Proceeding from reality and therefore, the current preference for a fixed diameter of pressure relief valves, pressure relief even when the actual pressure value slightly larger than large diameter of the actual relief valve pressure relief, but the effect is still feasible. Therefore, the pressure relief valve diameter can be used for the following: If the fire water mains diameter D ≤ 150mm, while the use of the pressure relief valve DN100; diameter mains water supply if the fire D> 150mm, while the use of the pressure relief valve DN150.



③ the pressure relief valve settings should be higher than the main fire pump and pressure regulator pump settings. When a regulator pump, the pump start and shut down two pressure regulator value (refer to regulator pressure pump run-time value). Regulators stopped pump pump water hammer pressure relief valve easily lead to misuse of open, so the stable high-pressure fire water supply system to eliminate a good reliable pump water hammer stop the technical measures, and should review the fire to the water distribution network in the water after the hammer residual pressure below the pressure relief valve settings to ensure that misuse does not open.



④ pressure relief valve should be provided with fire mains water supply connected to the branch pipe. Pressure relief valve to facilitate maintenance and to prevent misuse of the closure of control valves, pressure relief valve in the signal should be set up before the gate valve or butterfly valve signal. In order to maintain water pressure relief valve maintenance free, bypass pipe should be installed.



2 emergency shut down valve



Emergency shut down valve normally open, pressure in the pipe network of more than pressure settings automatically shut down to prevent the fire pump fire water run-time into the water tank, fire pump at the same time to prevent run-time in the life - the fire of life share the water supply system due to water supply accessories overpressure damage.



Recommended lives of our shared water supply and fire system. Such systems usually start life with lower pressure water pump, fire pump to start a fire when the value is much higher than the pressure pump to start when the pressure of life value, while the "architectural design code for fire protection," the first Paragraph Four of Article 8.6.3 provides that: "After the fire, fire pumps from the fire water supply should not enter the fire service water tanks." To solve this problem, should be in the pipeline to enter the fire service water tanks set up an emergency shut down valves.



At the same time to prevent the fire water pumps start living accessories overpressure should be mains water supply in the life of the emergency shut down valves.



Emergency closure of the pressure valve is set. If the pressure set too low, life starts pump will close the emergency shut down valves; if the pressure set too high, the emergency fire pump start valve does not close the closure. General, the pressure settings pump should be higher than life at the time of zero flow pressure, which is lower than the design of fire pumps at the time of the flow pressure value. At the same time, water mains must be reliable to take technical measures to prevent water hammer.



3 emergency open valve



Open the valves used in emergency fire water spray system, has not yet been implemented in engineering. Normally open valve emergency shut down, the pressure in the pipe network to reach the pressure set to open automatically when the value of water to prevent water spray fire-extinguishing system in the fire pump rated speed prior to reaching the low pressure water spray and the emergence of the phenomenon.



Fire water supply pipeline valve set to open more often, and require emergency open the valve normally closed, that is to start after a fire pump rated speed, the pressure pipeline network to meet the design requirements to open when the pressure value, which requires valves sluicegate normal and reliable. Emergency open valve and pressure relief valve is similar in nature, are open to reach the pressure values, the only difference is that the pressure relief valve opens, water discharge or returned to the pool fire to relief; emergency open valve opens, flow into the water spray fire-extinguishing system for fire fighting. Both areas belong to the hydraulic control valves are set up for the pilot of the needle, and needle and easy to plug due to impurities can not move; are used to control movement of diaphragm valve, diaphragm rubber material, easy to aging, wear and tear. These two components take the corresponding measures are: ① the needle pre-set multi-stage filter, the filter head level filters to narrow hole to retain solid particles of impurities; ② rubber separators are produced using quality products, and regularly check the diaphragm and hydraulic control valve in the case of spring.



At present, pressure relief valves, emergency shut-off valve and emergency valve to open the valve as common treatment, not included in the scope of the fire special valves, fire protection products without the adoption of Quality Supervision, Inspection and Test Center testing. I believe that this situation should be changed, pressure relief valves, emergency shut-off valve and emergency valve to open only for the fire water supply system should be incorporated into the fire as soon as possible the scope of special products. ball valve Trunnion Mounted Ball Valve Floating Ball Valve Top Entry Ball Valve Three way ball valve V Type Ball Valve
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