Principle and construction of hydraulic control valve
The hydraulic control valve is a valve that is opened, closed and regulated by the pressure of the pipeline medium. It consists of a main valve and attached conduits, needle valves, ball valves and pressure gauges. It can be evolved into a remote control float valve, pressure reducing valve, slow-closing check valve, flow controller depending on the purpose of use and functional location. , pressure relief valve, hydraulic electric control valve, emergency shut-off valve, etc. The pilot valve operates with the change of the liquid level and pressure of the medium. Due to the variety of pilot valves, it can be used alone or in combination, so that the main valve can be separately and comprehensively adjusted for water level, water pressure and flow rate. . However, the main valve body is similar to the stop valve. When the valve is fully open, the pressure loss is much larger than that of other valves, and the loss coefficient of each opening is close to the fully closed state, and the more the valve is larger, the larger the valve diameter is. Significant.
The valve with the above characteristics accelerates in the action close to the valve flap, and is prone to the impact of the water hammer. When the valve is nearly fully closed, the valve moves as slowly as possible, so that a throttle device can be arranged on the valve flap. In addition, the throttling and action parts of the pilot valve should be avoided as much as possible to avoid the clogging. If necessary, add a filter, regularly check and set the bypass line. The hydraulic control valve is divided into two types: diaphragm type and piston type. The working principle is the same. The pressure difference between the above and the downstream is the power. The pilot valve is controlled to make the diaphragm (piston) hydraulic differential operation, which is completely adjusted by hydraulic power, thus making the main The valve flap is fully open or fully closed or in a regulated state.
When the pressure water entering the control chamber above the diaphragm (piston) is discharged to the atmosphere or the downstream low pressure zone, the pressure acting on the lower part of the valve flap and below the diaphragm is greater than the pressure value above, thereby pushing the main valve flap to the full Open position: When the pressure in the control chamber above the diaphragm (piston) is between the inlet pressure and the outlet, the main valve flap is in an adjusted state, and its adjustment position depends on the combination of the needle valve and the pilot valve in the conduit system. Control role.
The pilot valve can open or close its own small valve port by the change of the downstream pressure, thereby changing the pressure value of the control chamber above the diaphragm (piston) and controlling the adjustment position of the main valve flap. Can be used in domestic water supply, fire protection systems and industrial water supply systems.
Classification and characteristics of hydraulic control valves:
According to the structure, the hydraulic control valve can be divided into two types: diaphragm type and piston type. The working principle is the same. Both the above-mentioned downstream pressure difference ΔP is the power, which is controlled by the pilot valve to make the diaphragm (piston) hydraulic differential operation, completely hydraulic. Automatic adjustment so that the main valve disc is fully open or fully closed or in a regulated state.
When the pressure water entering the control chamber above the diaphragm (piston) is discharged to the atmosphere or the downstream low pressure zone, the pressure acting on the bottom of the valve disc and below the diaphragm is greater than the pressure value above, so push the main valve disc to fully open When the pressure water in the control chamber above the diaphragm (piston) cannot be discharged to the atmosphere or the downstream low pressure zone, the pressure acting above the diaphragm (piston) is greater than the pressure below, so the main valve disc will be used. Pressed to the fully closed position; when the pressure in the control chamber above the diaphragm (piston) is between the inlet pressure and the outlet pressure, the main valve disc is in an adjusted state, the adjustment position depends on the needle valve in the catheter system and is adjustable The joint control of the pilot valve. The adjustable pilot valve can open or close its own small valve port by the downstream outlet pressure and change with it, thereby changing the pressure value of the control chamber above the diaphragm (piston) and controlling the adjustment position of the square valve disc.
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