Emergency shutdown valve is in recent years developed a new product. In engineering applications are increasing. In the installation process, we also found some problems, there are some construction problems, there are some design problems. A good product not only to better the quality of the product itself, the most important is to let everyone know it, know it, and the rational use of it, in order to play its biggest role.
One, why use the emergency shut-off valve
As you know, has always been the fire pipe network and life management are two water supply systems, water supply by two pumping systems, respectively, from the pump to the building for a long distance from the Road to piped water. Road due to the laying of such a large workload of pipeline construction, pipeline materials, double, and maintenance of a pipeline when the identification is also a lot of inconvenience; second, fire pipes for many years not to use, easy to rust, wall panels and interfaces for corrosion thinning, usually do not have no pressure, while the case of fire, a sudden pressure increase inside the tubes, easy to burst, resulting in fire system can not supply. Third, the Shanghai to promote water pump pumping directly from the municipal pipe network is no longer underground pool. This will not only eliminate the cost of the construction of the pool, while avoiding secondary pollution of the water. Maintaining the cleanliness of water sources to ensure people's health is the most important one. Because of the advantages of these areas, so the products are gradually being everyone's welcome.
Second, emergency shut-off valve works emergency shutdown valve is in a hydraulic control valve. Is from the main valve, throttle, guided valves, pressure gauges and other pipe fittings formed to take over. When the main valve inlet pressure below the set pressure valve guide, the guide valve is turned on at this time, the main valve cover chamber pressure and the main valve outlet pressure equal to, import and export existing differential pressure, flow through the valve port by exports out of . When the fire pump starting, or pump-pressure increases, more than lead valve set pressure, the import pass by the main valve guide valve control pipe pressure increases, the role of the spring pressure on the downward pressed to drive spool down, so that guide valve closed, this time the main valve inlet pressure through the throttle valve continuously added to the main valve cover chamber, due to valve flap downward pressure being greater than the upward thrust, the main valve closed. Please note that the key point is that the inlet pressure is less than set pressure of the valve has been turned on, inlet pressure is greater than set pressure, the valve is turned off. There are so many designers to the misconception that as long as the emergency shutdown valve installed, it will pass, do not say what conditions, it would be wrong.
Third, engineering problems we have encountered during the actual installation and testing of many unreasonable to propose for discussion. Plume is located in Shanghai Pudong Road there is a residential pump room on the ground floor, three 12-storey layer and two eight-story, floor 2.8 meters high, life pumps fire pumps are DN80, living pump head 53 meters, fire pump head 60 meters, Flow 10L / S, the water supply sub-Wu Lu, DN80 pipe into the rooftop water tank. From DN80 pump at the same time for the Wu Lu DN80 pipe, so pressure is not high, barely into the tank. Emergency shutdown valve to the pressure set at 0.5MPa, while for the Wu Lu water, pressure, no more than 0.5MPa, could only supply water to the water tank. However, if there are four water tank is full, liquid level control valve on the tank off, leaving only a tank of water still dissatisfied with pay, at this time the pressure will rise, more than 0.5MPa, emergency shut-off valve will be closed, The remaining one can not recharge the tank. In order to smoothly supply water tanks for every one, we need to be stable at the pressure 0.45MPa, so that is less than 0.5MPa, will not lead to the closure. This requires that pumps life add a pressure relief valve. Most units now, life is not set pump pressure relief valve. Some units use the electric contact pressure gauge, when the water pressure is increased automatically when the trip exceeds 0.5MPa, water pumps stop functioning, so that a single tank is still not solve the problem of replenishment.
The second problem is when the fire pump start, all of the emergency shutdown valve is open. DN80 pump sub-Wu Lu DN80 plumbing, this time, if dissatisfied with the tank water, water pressure would not increase, unlikely to exceed 0.5MPa, until the pool filled, liquid level control valve closed, pressure can rise. Here the designer should consider increasing the pump capacity, or reduce the pipe diameter, the two should be at least a difference of two files, such as water pumps replaced DN100, Wulu pipes replaced DN65, at this time the pressure can be more than 0.5MPa, since to close the role, in order to bring the water to the building fire service delivery. Another example, in Shanghai, there is a residential district Kongjiang DN100 fire pump, six road pipe DN80, still can not shut down, so multi-channel pumps and water pipes should be a difference of two files is appropriate.
The third problem is that the drainage system pump house, pressure relief valve discharge water should be discharged into the fire pool, or sewer and should not be ranked in a narrow ditch Ming. Or to cite the example described above, in the debugging Wu Lu pipes, all the way all the way to gradually shut down, resulting pump the water out of wholly on the pressure relief valve to vent the basement, drainage pump is far less than the fire pump, underground pumping station results flooded. The best option is to pump life and fire safety have adopted variable frequency pump, when debugging is not a constant pressure flow. Quantitative pumps or pressure relief valve can also be added, but the pressure relief valve necessary to the pool or in conjunction with the sewer pipe, sewer diameter than the inlet freshman to second gear. After the emergency shutdown valve valve through the user's program is better. Pipe network and live in fire between the pipe network is advisable to increase an anti-fouling cut off valve to prevent the return of contaminated fire water for domestic use. Figure 3.
The fourth question, the installation location of choice. So far, most users the location of emergency shutdown valves installed on the dumb wells. There is an emergency shutdown valve users to set up the staircase, I think on a more reasonable under the stairs for easy commissioning and maintenance. If on the dumb wells should allow sufficient space for maintenance, and some dumb well an area of only 40 × 60cm2, and has more than 1 meter deep, space is too small maintenance staff simply can not debug. And valves at both ends there is no expansion joints or soft joints, if the required repairs can not be removed again Zhuangshang Qu. Proposed dumb Wells area 60 × 80cm2, the depth should not be too deep to seal covers do not touch after the valve is appropriate. In addition, the need to add flexible connector or valve with a pick elbow.
The fifth issue, piping should be washed clean before opening. Debugging process, we found that emergency shutdown valve can not be closed, eliminating stress factors, suspected to have gravel in the body of memory to stay, after checking the valve 12 the majority of Taiwan have gravel retention, including two to the next body cavity filled. Therefore, the installation of emergency shut down valve should be cleaned before the pipeline, in order to ensure that all the valves work properly.
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