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 can be * a good pump to eliminate water hammer to stop the technical measures, and should review the fire water distribution network to have a water hammer in 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 (Figure 2). 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, the mains water supply must be taken to be * the 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 can be *. 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.
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