The valve is a device used to control the direction, pressure and flow of fluid in the fluid system, which can make the medium (liquid, gas, powder) in the piping and equipment flow or stop and control its flow. The valve is an important control part in the fluid transportation system.

Preparation before operation

Before operating the valve, read the operating instructions carefully. Before operation, be sure to know the flow direction of the gas, and pay attention to check the opening and closing signs of the valve. Check the appearance of the valve to see whether it is damped. If it is damped, dry it; if it is found that there are other problems, handle them in time and do not operate with faults. If the electric valve has been out of service for more than 3 months, check the clutch before starting. After confirming that the handle is in the manual position, check the insulation, steering and electrical circuit of the motor.

Correct operation of manual valve

Manual valve is the most widely used valve. Its handwheel or handle is designed according to common manpower, considering the strength of sealing surface and necessary closing force. Therefore, it is not allowed to move with long lever or long wrench. Some people are used to using the wrench, so they should pay strict attention to it. When opening the valve, they should use steady force to avoid excessive force, which will cause the opening and closing of the valve. The force should be stable and not be impacted. Some parts of high-pressure valves with impact opening and closing have considered the impact force and general valve can not be equal to each other.

When the valve is fully opened, turn the hand wheel back a little, so that the threads are tight to avoid looseness and damage. For open stem valves, remember the valve stem position when fully open and fully closed to avoid hitting the top dead center when fully open. It is convenient to check whether it is normal when it is fully closed. If the valve office falls off, or a large sundry is embedded between the valve core seals, the valve stem position will change when the valve is fully closed. Damage to valve sealing surface or valve handwheel.

Valve opening mark: when the groove on the top surface of the valve rod of ball valve, butterfly valve and plug valve is parallel to the channel, it indicates that the valve is in the full open position; when the valve rod rotates 90 to the left or right. When, the groove is perpendicular to the channel, indicating that the valve is in the fully closed position. Some ball valves, butterfly valves and plug valves open when the wrench is parallel to the channel, and close when the wrench is vertical. The three-way and four-way valves shall be operated according to the marks of opening, closing and reversing. Remove the movable handle after operation.