Emergency shut down valve is developed in recent years, new products. In engineering applications is increasing. In the installation and commissioning process, we also found some problems, there are some problems in construction, some design problems. A good product not only better the quality of the product itself, the most important thing is to make sure it should be familiar with it, reasonably use it to play its greatest role.
First, why should we use the emergency shut down valve
As we all know, has always been the fire control network and life are two water supply systems, water supply by the two pumps, respectively, from the pumping station to the building for a long distance from the water supply pipe Rd. Road due to the laying of this pipeline construction workload larger double pipe materials, as well as to identify the maintenance of a pipeline has a lot of inconvenience; the second, fire pipeline for many years not to use, easy to rust, wall panels and interface due to corrosion thinning, usually do not have no pressure, and in case of fire, a sudden pressure increase in tube, easy to burst, resulting in water supply systems can not fire. Third, the promotion of water directly from the Shanghai municipal pumping pipe network is no longer underground pool. This will not only save the cost of the construction of the pool, while avoiding secondary pollution of the water. To maintain the water clean, and ensure people's health this is the most important one. Because of the advantages of these areas, so the product is gradually welcomed by everyone.
Second, emergency shut down valve working principle
Emergency closure of the hydraulic control valve is a valve. By the main valve, throttle, guided valve, pressure gauge, as well as take over the other tube components. When the main valve inlet pressure below the set pressure valve guide, the guide in a valve open state at this time, the main valve cavity pressure above the main valve outlet pressure equal to the existence of import and export pressure, flow through the outflow valve port export . When the fire pump start-up or increased pump pressure, more than I. valve set pressure, the main valve by the import wizard increased pressure valve control, the role of pressure in the spring increases, pressed down, driven spool Down to guide valve closed at this time the main valve inlet pressure constantly replenished through the throttle valve to the main valve cavity covered, due to valve downward pressure by the upward thrust is greater than, the main valve to close. Please note the key point is that the inlet pressure is less than set pressure of the valve has been turned on, set the inlet pressure is greater than the pressure, the valve remained closed. Many designers now have the misconception that as long as the emergency shutdown valve installed, it will be related, do not say what conditions, it is wrong.
Third, problems in project
The actual installation and commissioning, we encountered many unreasonable, put forward for discussion. Yu Shan Road, Shanghai Pudong is located in a residential area. The pump room is located at the ground floor of a residential area, 3-storey 12-storey and two eight-storey, layer 2.8 meters high, fire pump pump life are DN80, living 53 meters lift pump, fire pump head of 60 m, flow rate 10L / S , water supply sub-Rd, DN80 pipe into the roof tank. At the same time, the water pump from DN80 Rd DN80 for water pipes, so water pressure is not high, only reluctantly entered the tank. Emergency shut down valves to the pressure set at 0.5MPa, Rd for water at the same time, the pressure no more than 0.5MPa, pay only for water tanks. However, if there are four full tanks, tanks on the surface control valve to close, leaving only a water tank still dissatisfied with pay, the pressure will increase at this time, more than 0.5MPa, emergency shut down valve will be shut down, The remaining tanks will not be able to pay the. In order to smoothly every tank pay, on the need to stabilize the pressure of 0.45MPa, so that less than 0.5MPa, it will not lead to the closure. This requires an additional pump in the life of a pressure relief valve. Most units have no life pump pressure relief valve. Some units use the electric contact pressure gauge, when the water automatically when hypertension tripping over 0.5MPa, water pumps stop running, it still will not solve the problem of a single tank of pay.
The second issue is when the fire pump start-up, all the emergency shut down valves are open. DN80 Rd DN80 pumps at the water pipes, water tank at this time if not satisfied, do not pressure on, it is impossible for more than 0.5MPa, until the pool filled, liquid level control valve closed, pressure can be increased. Here the designer should consider increasing the capacity of pumps, or water pipe diameter decreases, the difference between the two should be at least second gear, such as water pump replaced DN100, replaced water pipes Rd DN65, the pressure at this time to more than 0.5MPa, since to the closure of the role of fire in order to send water to the building. A further example, in Shanghai there are a控江讲residential quarters DN100 fire pumps, water pipes Road DN80, still can not shut down, so multi-channel pumps and water pipes should be appropriate for the difference between two files.
The third problem is that the drainage pumping systems, pressure relief valve should discharge water into the fire pond or drainage should not be prescribed in a small ditch. Or give examples on the above, when in debug Rd pipes, all the way to gradually shut down all the way, the results of pumping water out of China by the pressure relief valve on the basement, drainage pump is far less than the fire pump, the results of the underground pumping station flooded. The best option is the life of pumps and fire pump use, water pressure testing at a constant flow from the impact. Quantitative pumps or pressure relief valve can also be added, but the pressure relief valve necessary in conjunction with the pool water pipes or sewer, sewer inlet diameter than the first year to second gear. After an emergency shut down valve through the user's program is better. Network of fire and life should be to increase inter-network fouling off a valve to prevent return fire hose water pollution.
The fourth issue, the choice of installation location. So far, the majority of users to the location of emergency shut-off valve installed on the wells dumb. There is a user to set up an emergency shut down valve on the stairs, I think on a more reasonable under the stairs, easy to debug and maintenance. Wells should be as dumb on the maintenance of sufficient space, and some dumb well an area of only 40 × 60cm2, but more than 1 meter deep, space is too small maintenance staff simply can not debug. And there is no expansion joints at both ends of the valve or soft joints, if required can not be removed搭下去maintenance. Area of the proposed wells dumb 60 × 80cm2, the depth should not be too deep to stamp covers do not touch after the appropriate valves. In addition, the need to increase or soft joints bend valves have an access.
The fifth point is that before the opening of the pipeline should be in the running water. We found in the debugging process can not close the emergency shut-off valve, remove the pressure of factors, suspected of having little stones stay in the body memory, the check valve 12 the majority have little stones remaining, including two under the body cavity of filled. Therefore, the installation of emergency shut down valve should be cleaned before the pipeline, the valve in order to ensure that all work properly. valve ball valve gate valve check valve globe valve butterfly valve
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