In the feed water pump station, in order to make the centrifugal pump start lightly, it is usually required to close the outlet valve of the pump first and then start the pump unit. When the speed reaches the rated speed, the outlet valve will be opened gradually. In order to prevent the reverse flow of medium in the system, The check valve must be installed at the outlet of the pump; as a result of the instantaneous closure of the ordinary swing check valve, water hammer accidents that threaten the pump system often occur, an effective water hammer elimination device is also to be provided. Currently used more electric butterfly (gate) valve supporting micro-resistance slow closing check valve to achieve the above purpose, but in the field of use electric butterfly (gate) valve often appears to be closed, motor burnout and gear reduction gear Damage and other failures: The slow-closing micro-resistance check valve to adapt to a narrow range, can not adapt to large changes in flow, pressure, and its regulation needle easy to block, leading to the damper can not move and other failures affect the normal safe water supply. First, the multi-functional pump control valve Description: Multi-function pump control valve: a new type of hydraulic control valve, a valve alternative electric butterfly (gate) valve, check valve and water hammer eliminator three devices. It can automatically open the pump when the slow opening, closing the pump when the closure and slow closure, without any electrical control and other power and manpower, but also without the hydraulic device. The main advantages of multi-function pump control valve: (1) no operational control. When using the pump start and stop the valve before and after the water pressure difference as a control power, with the opening and closing of the pump automatically opens and closes the function. (2) Valve opening and closing movements can effectively prevent accidents caused by water hammer pressure wave. According to field use survey and measured, stop the pump water hammer pressure peak at 1.3 times the working pressure. (3) Without on-site commissioning, a wide range of applicable conditions. (4) basically no maintenance. As a valve to replace the three valves, maintenance and repair workload greatly reduced. (5) resistance loss is small. The use of streamlined, wide body design, resistance loss than the same kind of products abroad to reduce more than 50%, such as DN200 products in the v = 2m / s economic flow conditions, multi-functional pump control valve loss of 0.7m, while foreign similar products Is 1.5m. Second, the structure and working principle of multi-function pump control valve 1, structure: Multi-function pump control valve structure consists of the main valve and external accessories. The main valve includes the valve body, the main valve plate, slow closing valve plate, valve stem, seat and diaphragm controller (including valve cover, diaphragm seat, diaphragm, diaphragm pressure plate): external accessories control valve, filter , Emptying valve, micro check valve. One micro-check valve is a special accessory, in its non-return direction with a current limiting hole. See Figure 2 for installation. 2, the working principle: 1), before the pump starts, the valve outlet pressure on the role of the main valve plate, the valve is closed, while the diaphragm controller connected to the pressure on the water chamber, the lower chamber is connected to the low pressure valve inlet. 2) When the pump is started, the inlet pressure of the valve will gradually increase. At the same time, the pressure water will slowly enter the lower chamber of the diaphragm controller through the connecting pipe at the inlet of the valve, enabling the main valve plate to slowly open. The opening speed can be adjusted through the control valve. 3), the pump downtime, the pressure of the valve to reduce the import, when approaching zero flow, the main valve plate under its own gravity quickly closed. As the pressure at the inlet of the valve is reduced, the pressure water at the outlet of the valve enters the upper chamber of the diaphragm controller through the connecting pipe, the lower chamber water is pressed back to the inlet of the valve through the connecting pipe at the inlet of the valve, the slowly closing valve plate is slowly closed, Adjust by control valve. The closure of the main valve plate and the slow closure of the slow closing plate complies with the two-phase closing rule, which can effectively eliminate the water hammer. Third, the multi-function pump control valve in the safe water supply applications: (a few technical issues) 1, connecting pipe parts design: 1), micro-check valve is to ensure that the valve opening time is greater than the motor start-up time, so that the motor Light load start; at the same time to avoid opening the valve due to excessive pressure caused by water hammer. Valve opening time by the control valve according to field conditions pressure settings. 2), the control valve can adjust the flow rate of the upper and lower chambers of the diaphragm controller so as to adjust the slow closing time; the diaphragm controller can be repaired when closed; and the valve can be manually operated when the pump is in normal operation. 3), the filter is to ensure the membrane controller on the water chamber cleanliness. As the valve in a process of opening and closing the water is reciprocating access, itself has the role of backwash, it can also be used for poor medium conditions. 2, the valve to eliminate water hammer characteristics: 1), from the principle of destructive water hammer shows that there are two main factors to reduce the water hammer boost: (1) in the water flow just before cutting v as small as possible Close to zero) to close the main valve plate; (2) to make the valve closing time t is the hammer phase u = 2L / α (α - pressure wave transmission speed, m / s; -10 times, you can limit the actual water hammer pressure h within the safe range, thus eliminating the damaging water hammer damage. 2), multi-function pump control valve opening of the main valve plate is determined by the size of the impact of water flow in the pipeline, the main valve plate opening at high flow rate is large: when the flow rate decreases valve plate opening is small: the flow rate close to zero The main valve plate is closed. The whole process is consistent with the elimination of the principle of water hammer close fast, so the elimination of water hammer works well. 3), multi-function pump control valve slow closing valve plate must be formed in the diaphragm controller pressure difference before and after the cavity can be achieved that the main valve plate is closed, the slow closing valve plate can only be closed, it is impossible to produce Slow closing and closing the phenomenon of synchronization. 3, the valve resistance characteristics: In order to reduce water flow resistance, the design reduces the weight of the main valve plate, while using streamlined spacious body design. The Hunan Hydraulic Machinery Quality Supervision authorized station test, DN200 multi-function pump control valve resistance coefficient of about 3.8, while the same specifications of the pipe swing check valve resistance coefficient of 5.5. 4, the diaphragm design The diaphragm quality is a direct impact on valve performance and service life of the key components, after a variety of screening, the selection of neoprene as raw materials, the middle nylon mesh to strengthen; by the Hunan Rubber Quality Supervision Authorized station testing, 650,000 fatigue fatigue without rupture, can be used for more than 10 years. 5, no other external maintenance of hydraulic or electric components, the basic without repairs, and the use of wide bonnet, valve components can be removed completely, easy maintenance. Third, the conclusion: After the on-site use proved that multi-function pump control valve can effectively eliminate destructive water hammer, water supply system to improve the safety and reliability of significant features and ease of commissioning and installation, ease of operation and management, less maintenance, Meet the "2000 City Water Supply Technology Development Plan" in the water supply equipment automation, mechanization and modernization requirements, is the replacement of pumping station new valve products.