Emergency shutdown valve is the new product developed in recent years. In engineering applications is growing. In the installation process, we also found some problems, there are some construction problems, there are some design problems. The quality of a good product not only to better the product itself, the most important thing is to let everyone know it, know it, the rational use of it, in order to play its biggest role.
Why use the emergency shutdown valve
As we all know, has always been the fire pipe network and life management are two water supply systems, respectively by the two pump water, pump to the building from a long distance from the two water supply pipeline. Two road due to the laying of such a large workload of pipeline construction, pipeline material twice, and repair 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 and interface 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, no underground pool. This will not only save the cost of construction of the pool, while avoiding the two pollution sources. Keep the water clean, to ensure people's health is the most important one. Because of the advantages of these areas, so the products are gradually popular.
Working principle of the emergency shutdown valve
Emergency shutdown valve is a hydraulic control valve in the. It is composed of a main valve, throttle valve, pilot valve, pressure gauges and other fittings over. When the main valve inlet pressure below the set pressure valve guide, the guide valve is in the open state at this time, the main valve cover chamber pressure and the main valve outlet pressure is equal, there is import and export pressure, flow through the valve port export. When the fire pump start, or pump pressure increases, more than pilot valve set pressure, the import pass by the main valve guide valve control pipe pressure increases, the role of pressure in the spring, pressed down, drive spool down, the pilot valve closed, when the main valve inlet pressure through the throttle constantly added to the main valve cover chamber, the valve flap downward because of the pressure is greater than the upward thrust, the main valve closed. Please note that the key point is, the inlet pressure is less than set pressure of the valve has been turned on, the inlet pressure is greater than the set pressure, the valve in the closed state. There are many designers mistakenly think that if the emergency shutdown valve installed, it will pass, do not say what conditions, it would be wrong.
Engineering problems
We met many unreasonable places in the actual installation process, put forward for discussion. Located in the Shanghai Pudong feather Hill Road, a residential area. This residential area pump room on the ground floor, three buildings of twelve stories and two buildings of eight stories, the height of 2.8 meters, living pumps fire pumps are DN80, living pump head 53 meters, fire pump lift 60 meters, flow rate 10L/S, water supply five road, DN80 pipe into the roof water tank. At the same time for the five DN80 from DN80 pump water, so water pressure is not high, barely into the tank. Emergency shutdown valve to the pressure set at 0.5MPa, for five water at the same time, the pressure is not more than 0.5MPa, only the tank water. However, if there are four water tank is full, tank's liquid level control valve closed, leaving only a tank of water still dissatisfied, then the pressure will rise, more than 0.5MPa, emergency shut-off valve is closed, the rest of a water tank can not pay up. In order to make each tank can smoothly supply water, the pressure on the need to stabilize at 0.45MPa, so less than 0.5MPa, will not lead to the closure. It needs to add a pressure relief valve in the pump life. Now most of the units, life is not set pump pressure relief valve. Some units use the electric contact pressure gauge, when the water pressure exceeds 0.5MPa automatically trip, water pumps stop running, so still can not solve the water problem of single tank.
The second problem is when the fire pump start, all the emergency shutdown valve is in the open state. DN80 pump is divided into five DN80 pipe, if dissatisfied with the tank water, water pressure would not go, can not be more than 0.5MPa, until the pool filled, liquid level control valve closed, pressure can be increased. Here the designer should consider increasing the pump capacity, or reduce the pipe diameter, the two should be at least between the two files, such as water pumps to DN100, five way pipes to DN65, the pressure at this time to more than 0.5MPa, function to close, in order to get water to the building fire. For example, in a residential district road Shanghai Kongjiang DN100 fire pump, six way pipe DN80, still can not shut down, so multi-channel pumps and water pipes between the two files should be suitable.
The third question is, the drainage system pump house, pressure relief valve discharge water should be discharged into the fire pool or sewer, shall not be discharged in a small ditch. Or to cite the example described above, in the debugging five way pipe, a way to gradually shut down, pump the water out of the results from all the pressure relief valve discharge in the basement, drainage pump is far less than the fire pump, the results of underground pumping station flooded. The best solution is to pump life and fire pump frequency are used, debugging is not constant pressure flow. Quantitative pumps or pressure relief valve can also be, but the pressure relief valve is necessary to pool together with the water or sewer, sewer diameter than the inlet pipe freshman from file. Emergency shutdown valve through the user's program is better. In the fire control network and the gateway should increase an anti-fouling cut off valve to prevent backflow of water, living water pollution.
The fourth question, the choice of installation location. So far, the majority of users to the emergency shutdown valve installed on the dumb wells. There is a user to set the emergency shut off valve under the stairs, I think on a more reasonable under the stairs, easy to debug and repair. When placed in a staple should leave enough space for repair, some staple area is only 40 × 60cm2, and there are more than 1 meters deep, the space is too small repair personnel cannot debug. Valve ends and no expansion joints or soft joints, if required to remove the repair can not put up. Suggest staple area of 60 * 80cm2, the depth should not be too deep to cover after cover, do not touch the valve is appropriate. In addition, the need to add flexible connector or valve has a connection elbow.
The fifth issue, the pipeline should be clean before opening. We found that the emergency shutdown valve can not be closed in the debugging process, eliminating stress factors, suspected of having stones in the body of memory to stay, the check valve 12 most have gravel retention, including two to the lower body cavity filled. So in the installation of emergency shut down valve should be cleaned before the pipeline, to ensure the normal operation of valves all.
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