Valve is a kind of pipeline accessory. It is a device used to change the section of pipeline and the flow direction of the medium, and control the pressure, flow and temperature of the conveying medium. Specifically, it has the following uses:
1. Connect or cut off the medium in each section of the pipeline, such as: gate valve, globe valve, butterfly valve, ball valve, cock, etc.
2. Adjust the flow and pressure of the pipeline, such as: regulating valve, throttle valve, pressure reducing valve, butterfly valve, ball valve, etc.
3. Change the flow direction of the medium, such as: distribution valve, three-way cock, three-way ball valve, etc.
4. Used for overpressure protection, such as: safety valve, relief valve.
5. Prevent the back flow of the medium in the pipeline, such as: check valve
6. Indicate and adjust the liquid level, such as: liquid level indicator, liquid level regulator, etc.
7. Separate air and water in pipelines, such as steam traps and air traps.
8. Temperature regulation in the pipeline, such as: temperature regulating valve, temperature and pressure reducing device.
Manual valves are valves operated by handles and handwheels, and are commonly used on equipment pipelines. Its handle and handwheel rotate clockwise to close, and counterclockwise to open. However, there are also individual valve openings that are opposite to the above openings. Therefore, pay attention to check the opening and closing signs before operation.
The hand wheel and handle on the valve are designed according to normal manpower. Therefore, in the use of the valve, the operator is not allowed to open or close the valve with the help of levers and long wrenches. Handwheels and handles with a diameter (length) of <320mm are only allowed to be operated by individuals. Handwheels with a diameter of >320mm allow two people to operate together, or allow one person to operate the valve with an appropriate lever (generally no more than 0.5m in length). However, diaphragm valves, pinch valves, and non-metallic valves are strictly prohibited to use levers or long wrenches to operate, and it is not allowed to close the valves excessively.
For valves such as gate valves and globe valves, when closed or opened to the end (that is, bottom dead center or top dead center), they must be rotated 1/4 to 1/2 turn to make the threads more tightly closed, which is advantageous for operation, so as not to be too tight. Damaged valve parts.
Some operators are accustomed to using levers and long wrenches to operate, thinking that the greater the closing force, the better, but this is not the case. This will cause premature damage to the valve and even cause an accident.