Abstract: The new multi-function pump control valve installed on the outlet pipe of centrifugal pump has three functions of gate valve, check valve and water hammer eliminator at the same time. This article describes the multi-function pump control valve structure, performance parameters, working principle, installation and commissioning, precautions. First, the functional requirements Centrifugal pump is the most commonly used water supply and drainage pump, usually in order to ensure the normal operation of the pump, the pump outlet pipe according to the need to install a gate valve, check valve and water hammer eliminator three kinds of valve Pieces, these three kinds of valve parts in the operation of the pump play a different role in each: the valve is usually closed, the valve starts to slowly open the valve, the pump down, the valve slowly closed first. Pump closed and closed parking brake, can effectively prevent the pump water hammer and pump stop water hammer at the same time, reduce the motor load when the pump starts, the pump at zero flow when the shaft power minimum, generally only the design axis 30% of power. Another function of the gate valve is to provide a safe overhaul condition for valves and pumps such as check valves installed between the gate valve and the pump when the gate valve is closed to prevent water backflow from the pressurized water pipe; Electricity caused by changes in the flow of water to prevent backflow; However, the sudden closure of check valve easy to produce water hammer phenomenon. When the geometry of the pump is high, the severe water hammer instantaneous high pressure can cause the pipe to rupture and serious production accidents occur. Water hammer to prevent the destruction of the water pipeline, often in the water pump pressure pipe to install water hammer eliminator. In order to automate pump operation, simplify management, reduce labor and improve reliability, people use hydraulic valves and electric valves to replace manual valves, and carry out a number of technical improvements on single valves. Hydraulic valve opening and closing, automatic slow closing valve, two-speed valve and other new self-closing valve. The above measures have achieved a certain effect in the application practice, but still unsatisfactory, the use of pressure sensing and electrical transmission control complex faults more single valve improvements can not solve the main problems of automatic operation. Therefore, people have been committed to the development of a valve with both gate valve, check valve and water hammer eliminator three valve function, reducing the footprint at the same time meet the above comprehensive requirements. JD745X-type multi-function pump control valve is one of the better, it has a valve multi-energy, reliable operation, easy operation, easy maintenance, according to the pump operating requirements of the automatic operation of the advantages of very welcomed by users. The multi-function control valve working pressure of sub-1.0MPa and 1.6MPa, 2.5MPa three kinds of action pressure greater than or equal to O.1MPa, medium temperature 0--80 â„ƒ, slow closing time in 3 -90s within the regulation, the pipeline flow rate of 2m / s when the pressure loss is less than 0.01MPa, water hammer peak less than 1.5 times the working pressure, nominal diameter DN50-DNl0000. Second, the basic structure of the overall size of the valve with the ordinary check valve by the main valve and external accessories. Among them, the main valve includes valve body, pressure plate and diaphragm, large valve plate, slow closing valve plate, valve seat, stem assembly and other components. Slow valve plate assembly with the pressure plate and the diaphragm connected together, the diaphragm pressed between the bonnet and the diaphragm seat, the diaphragm up and down movement of slow-moving valve plate up and down. Stem through the center of the large hole in the valve plate, because of the large valve plate can slide along the stem within a certain range. Normally, the large valve plate in the deadweight and the upper pressure spring under the pressure on the valve seat, the valve is closed. Multifunctional pump control valve external accessories installed on both sides of the valve diaphragm and the valve into and out of the pipe, diaphragm and valve inlet side of the lower connection pipe is equipped with control valves, filters and a special anti-stop valve. The upper chamber of the diaphragm and the outlet side of the valve are provided with a filter and a control valve only. Main valve in the valve plate and the slow closing plate movement and the location of the valve determines the status changes and opening and closing. Valve external fittings and piping at any time before and after the valve pressure changes delivered to the valve by the diaphragm into the upper chamber and the lower chamber to control the large valve plate and slow closing valve plate movement and accessories can be adjusted by changing the large valve plate and Slow closing valve plate speed, so that the valve opening and closing time within the prescribed range. Third, the working principle of multi-function pump control valve in the pump start-off is automatic work, the following were described the working principle of the process: (1) stop the pump state, the valve plate in the outlet and the diaphragm cavity static pressure Close all. (2) When the pump is started, water pressure is transmitted from the bypass pipe to the lower chamber, and the main valve plate and the slow-closing valve plate are slowly opened under the water pressure at the inlet end and the lower chamber. (3) In the water inlet pressure, the valve plate rose to the maximum opening state, the opening height by the flow of the decision. (4) stop pump moment, the sudden drop in flow and pressure, the main valve plate under the action of gravity began to slide down Chiang. (5) When the flow is close to zero, the main valve is closed, the main valve plate to leave a leak to reduce the impact of water hammer; the main valve plate, forming a pressure difference, the valve outlet water pressure from the bypass pipe into Upper chamber to promote the diaphragm plate, so that the lower row of water into the human valve imports, slowly closing the valve plate began to slow closure. (6) slow closing valve plate completely close the drain hole, the valve back to the initial state of the pump. Fourth, the installation and commissioning In the pump multi-function control valve installation, first check the main valve is intact, the fastener should be no loose, the attachment is complete. Then, install it according to the installation plan of multi-function control valve. Pay attention to control the access of the main valve and the working position of the valve on the pipe. Check valve with a control Tube
, one end connected to the diaphragm under the cavity, the other end of the human valve inlet pipe. One end of the other control tube is connected to the upper chamber of the human membrane and one end is connected to the outlet pipe of the valve; the adjustment and control valve in FIG. 3 should be fully open. The main valve should be installed horizontally, and pay attention to the direction of the valve body should be the same direction with the flow, not anti-installed. Valve cover and diaphragm seat exhaust valve and drain valve is the first multi-purpose control valve exhaust and drainage purposes, and usually off. According to the use of the valve can be used to adjust the main valve opening and closing speed. Debugging if found that the main valve can not be opened, should be carefully controlled according to Figure 3, check the control tube is connected; control tube should open the valve has been opened, the filter is blocked. When it is found that the main valve is not closed properly, it should first check the installation position of the control pipe and the valve on the pipe. If the main valve is repeatedly turned on and off several times, the pump still has the reverse phenomenon, indicating that the valve has foreign matter or valve Plate damage; diaphragm control room lower chamber exhaust, intake also water outflow, can determine the diaphragm damage.
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