Multifunctional pump control valve structure and working principle

Multifunctional pump control valve structure and working principle

I. Multifunctional pump control valve introduction

　　Multifunctional water pump control valve is a new type of hydraulic control valve. A valve can replace the electric butterfly valve, check valve and water hammer eliminator. It can automatically realize the slow opening when the pump starts, and the fast closing and slow closing when the pump stops, without any electric control, other power and manpower, and without hydraulic device.

　　The main advantages of multi-function water pump control valve are:

　　(1) no need for operation control. The water pressure difference before and after the valve when the pump starts and stops is used as the control power, and it has the function of automatic opening and closing with the pump starting and stopping.

　　(2) Valve opening and closing process can effectively prevent accidents caused by the surge pressure wave rise. According to the field investigation and actual measurement, the peak value of pump stopping surge pressure is within 1.3 times of the working pressure.

　　(3) No need for on-site commissioning, applicable to a wide range of working conditions.

　　(4) Basic maintenance is not required. As a valve instead of more than three valves, the maintenance workload is greatly reduced.

　　(5) Small resistance loss. Streamlined wide valve body design, resistance loss than similar foreign products to reduce more than 50%. For example, DN200 products in V = 2m / s economic flow, multi-functional water pump control valve loss of 0.7m, while similar foreign products loss of 1.5m!

　　Second, the structure and working principle of multifunctional pump control valve

　　2.1 Structure

　　Multifunctional water pump control valve structure is shown in Figure 1, composed of the main valve and external accessories. The main valve includes the valve body, the main valve plate, slow closing valve plate, valve stem, valve seat and diaphragm controller (including the valve cover, diaphragm seat, diaphragm and diaphragm pressure plate); external attachments include control valves, filters, evacuation valves and miniature check valves. Among them, the miniature check valve is a special accessory with a flow restriction hole in its check direction. The installation form is shown in Figure 2.

　　2.2 Working principle

　　Before the pump starts, the pressure of the valve outlet acts on the main valve plate and the valve is in the closed position. At the same time, the upper chamber of the diaphragm controller is connected with the pressure water, and the lower chamber is connected with the low pressure at the valve inlet.

　　After the pump starts, the valve inlet pressure gradually increases, while the pressure water slowly enters the lower chamber of the diaphragm controller through the connecting pipe at the valve inlet end, realizing the slow opening of the main valve plate, and the opening speed can be adjusted by the control valve.

　　When the pump stops, the valve inlet pressure drops, when the flow rate is close to zero, the main valve plate closes quickly under its own gravity. As the pressure at the inlet end of the valve decreases, the pressure water at the outlet end of the valve enters the upper chamber of the diaphragm controller through the connecting pipe, and the water in the lower chamber is pressurized back to the inlet end of the valve through the connecting pipe at the inlet end of the valve, and the slow-closing valve plate closes slowly, and the slow-closing time can be adjusted by the control valve. The fast closing of the main valve plate and the slow closing of the slow closing valve plate conforms to the two-stage closing law, which can effectively eliminate water hammer.

　　Third, several technical issues

　　3.1 Connection pipe component design

　　The role of the miniature check valve is to ensure that the valve opening time is longer than the motor start-up time, so that the motor can be started under light load; at the same time, to avoid starting the pump water hammer due to the valve opening speed is too fast. Valve opening time can be set by the control valve according to the site working pressure. The control valve can regulate the speed of water flow in and out of the upper and lower chambers of the diaphragm controller, thus regulating the slow closing time; when the diaphragm controller is closed, it can be repaired; the valve can also be operated manually to open and close the valve during the normal operation of the pump.

　　The filter ensures the cleanliness of the water in the upper and lower chambers of the diaphragm controller. As the valve's water flow is reciprocating in and out of the opening process, itself has the function of backwashing, so it can also be used in poor media conditions.

　　3.2 Water hammer elimination characteristics of the valve

　　According to the principle of destructive water hammer, to reduce the water hammer pressure rise of the main factors are two: (1) in the upcoming cut off before the water velocity V as small as possible (close to zero), close the main valve plate; (2) the valve closure time t for the water hammer phase u = 2l / (- pressure wave propagation speed, m / s; l - pipeline length, m) of the 5-10 times, the actual wheeze pressure H can be limited to within the safe range, thus Eliminate destructive water hammer hazards.