The Principle of Emergency Shutdown Valve
Emergency shutdown valve is a new high tech product, which has advantages of energy conservation, environmental protection and convenient and fast operation. Nowadays, fire protection is applied more frequently in building. In use, there are some problems with construction or design. A good product not only with high quality, but also has characters of convenience, simple operation and convenient maintenance.
The working principle of emergency shutdown valve
Emergency shutdown valve is one of the hydraulic control valve, which consists of the main valve, throttle valve, pilot valve, pressure gauge, joint and other pipe fittings. When the main valve inlet pressure is lower than the pilot valve set pressure, the pilot valve is in open state. When the main valve cavity pressure on the cover is equal to its outlet pressure, there is a pressure gap between inlet and outlet. The water flow through the valve mouth to outlet. When the fire pump starts up or variable frequency pump pressure increases, and more than the set pressure of pilot valve, the control valve pressure from the main valve inlet to pilot valve will increase, then, the pressure on the spring will increase, pushing down and compressing will drive the valve core move down, making the pilot valve closed. At this time, the main valve inlet pressure through the throttle valve is added to the valve cover cavity, for the downward pressure of disc is greater than the thrust upward, leading to the main valve closed. Please pay attention to the key point is that if the inlet pressure is less than the set pressure, the valve has been in an open position, if inlet pressure is greater than the set pressure, the valve is closed. There are many designers think that as long as the emergency shut-off valve is installed, it will pass without condition. It would be wrong.
Why use emergency shutdown valve
Fire control pipe network and pipe for life always are two different water supply system, and they supply water respectively. The water of a long distance from the pump house to building is supplied by the second pipe line. Firstly, his second pipeline construction needs larger workload; piping material cost twice as much; and it is inconvenient to identify a particular pipe for maintenance; Second, if the fire pipeline is not used for years, it will be easy to rust, pipe wall and interface will be thinner due to corrosion. Because of no pressure usually, once there is a fire, the pipe pressure will increase suddenly, easy to burst, rendering to the fire protection system can’t supply water. Third, Shanghai has promoted that they pump water directly from Shanghai municipal pipeline pump and no longer set the underground pool. This pattern not only has saved the cost of the pool building, but also has avoided the secondary pollution of water, which can keep the water clean and healthful. This is the most important item.
The problems existing in the project
1. When the fire pump start up, all the emergency shutdown valve is fully open.
The third problem is the drainage system of the water pump room, the water discharged from pressure relief valve should drain into fire pool or sewer, instead of going into narrow open trench.
2. Install location. So far, the majority of users install the emergency shutdown valve inside the staple. There's a user set the emergency shutdown valve under the stairs, which is a reasonable choice, for it is convenient to debug and repair.
3. The line should be rinsed clean before enabled. When finding emergency shut off valve cannot be closed, ruling out stress factors, people should take small stones reserved in the valve body into consideration. Some inspection show that small stones have been found in many valves, and even the lower part of valve cavity stuffed with small stones. So before installing the emergency shutdown valve, pipeline should be clean, to ensure that all the valves can work properly.
The working principle of emergency shutdown valve
Emergency shutdown valve is one of the hydraulic control valve, which consists of the main valve, throttle valve, pilot valve, pressure gauge, joint and other pipe fittings. When the main valve inlet pressure is lower than the pilot valve set pressure, the pilot valve is in open state. When the main valve cavity pressure on the cover is equal to its outlet pressure, there is a pressure gap between inlet and outlet. The water flow through the valve mouth to outlet. When the fire pump starts up or variable frequency pump pressure increases, and more than the set pressure of pilot valve, the control valve pressure from the main valve inlet to pilot valve will increase, then, the pressure on the spring will increase, pushing down and compressing will drive the valve core move down, making the pilot valve closed. At this time, the main valve inlet pressure through the throttle valve is added to the valve cover cavity, for the downward pressure of disc is greater than the thrust upward, leading to the main valve closed. Please pay attention to the key point is that if the inlet pressure is less than the set pressure, the valve has been in an open position, if inlet pressure is greater than the set pressure, the valve is closed. There are many designers think that as long as the emergency shut-off valve is installed, it will pass without condition. It would be wrong.
Why use emergency shutdown valve
Fire control pipe network and pipe for life always are two different water supply system, and they supply water respectively. The water of a long distance from the pump house to building is supplied by the second pipe line. Firstly, his second pipeline construction needs larger workload; piping material cost twice as much; and it is inconvenient to identify a particular pipe for maintenance; Second, if the fire pipeline is not used for years, it will be easy to rust, pipe wall and interface will be thinner due to corrosion. Because of no pressure usually, once there is a fire, the pipe pressure will increase suddenly, easy to burst, rendering to the fire protection system can’t supply water. Third, Shanghai has promoted that they pump water directly from Shanghai municipal pipeline pump and no longer set the underground pool. This pattern not only has saved the cost of the pool building, but also has avoided the secondary pollution of water, which can keep the water clean and healthful. This is the most important item.
The problems existing in the project
1. When the fire pump start up, all the emergency shutdown valve is fully open.
The third problem is the drainage system of the water pump room, the water discharged from pressure relief valve should drain into fire pool or sewer, instead of going into narrow open trench.
2. Install location. So far, the majority of users install the emergency shutdown valve inside the staple. There's a user set the emergency shutdown valve under the stairs, which is a reasonable choice, for it is convenient to debug and repair.
3. The line should be rinsed clean before enabled. When finding emergency shut off valve cannot be closed, ruling out stress factors, people should take small stones reserved in the valve body into consideration. Some inspection show that small stones have been found in many valves, and even the lower part of valve cavity stuffed with small stones. So before installing the emergency shutdown valve, pipeline should be clean, to ensure that all the valves can work properly.
