Gate valve installation and maintenance should note the following: Hand wheel, handle and transmission are not allowed to lift, and no collision. Double gate valve should be installed vertically (ie stem in a vertical position, the hand wheel at the top). The gate valve with bypass valve should open the bypass valve before opening (to balance the pressure difference between inlet and outlet and reduce the opening force). Gate valve with transmission, according to the instructions of the product installation instructions. If the valve often switch the use, at least once a month lubrication. Gate valve is used as a cut-off medium, the whole flow through the full open, then the pressure loss of medium operation minimum. Gate valve is usually applied to do not often need to open and close, and keep the gate fully open or fully closed conditions. Not suitable for use as a regulator or throttling. For high-speed flow media, the gate may cause gate vibration when the gate is open partially, and the vibration may damage the sealing surface of the gate and valve seat, which can cause the gate to suffer erosion of the medium. The main difference from the structural form is the form of the sealing element used. According to the form of the sealing element, the gate valve is often divided into several different types, such as wedge gate valve, parallel gate valve, parallel double gate gate valve, wedge double gate gate and the like. The most common forms are wedge gate valves and parallel gate valves. The purpose of this type of valve is to allow only the medium to flow in one direction and to prevent the flow in the direction. Usually this kind of valve is automatic working, the valve flap opens under the pressure of the fluid flowing in one direction; when the fluid flows in the opposite direction, the valve flap is acted upon by the fluid pressure and the self-weight of the valve flap to cut off the flow. Which check valve belongs to this type of valve, which includes the swing check valve and lift check valve. Swing check valves have a hinged hinge mechanism and a flap-like flap freely rests against the slanted seat surface. To ensure that the valve flap reaches the proper seating surface every time, the valve flap is designed on the hinge mechanism so that the valve flap has enough swivel-open space for true and complete valve flap contact. The valve flap can be made entirely of metal, or it can be fitted with a leather, rubber or synthetic cover over the metal, depending on the performance requirements. Swing check valve in the fully open condition, the fluid pressure is almost unimpeded, so the pressure drop through the valve is relatively small. Lift check valve seat is located on the valve seat sealing surface. In addition to the valve flap valve can be free to rise and fall, the rest of the same as the cut-off valve, the fluid pressure so that the valve flap from the valve seat lifting surface, the media back to cause the valve flap down to the seat, and cut off the flow. Depending on the conditions of use, the valve disc can be of all-metal construction or it can be in the form of a rubber gasket or rubber ring inlaid on the valve disc holder. Like the stop valve, the passage of fluid through the lift check valve is also narrow, so the pressure drop through the lift check valve is larger than the swing check valve and the flow through the swing check valve is limited Few. In the production process, in order to make the medium pressure, flow and other parameters in line with the process requirements, the need to install the adjustment mechanism to adjust the above parameters. The main working principle of the adjusting mechanism is to change the valve disc and the flow area between the valve disc and valve seat to achieve the purpose of adjusting the above parameters. Belong to this type of valve collectively referred to as the control valve, which is divided into rely on the media itself driven by self-driven control valves such as pressure relief valves, pressure regulators, etc., where the leading power-driven (such as electricity, compressed air and liquid Power) called his drive control valves, such as electric control valve, pneumatic control valve and hydraulic control valve.
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