Manual valve is a valve operated by handle and hand wheel, which is commonly used in equipment pipeline. Its handle and hand wheel turn clockwise to close and counter clockwise to open. However, there are separate valves opposite to the above. Therefore, attention should be paid to check the opening and closing signs before operation. The handwheel and handle on the valve are designed according to normal manual operation. Therefore, the use of the valve does not allow the operator to open or close the valve through lever and long wrench. Handwheel, handle diameter (length) 320mm, handwheel allows two people to work together, or allows one person to operate the valve with appropriate lever (generally not more than 0.5m long). Valves such as valves and stop valves, such as closing or opening the head (i.e. bottom dead center or top dead center), should be rotated 1 / 4 to 1 / 2 turn to make the thread more suitable, which is beneficial to avoid over tightening and damage. Valve parts. Some operators are used to using levers and long spanners. The greater the closing force, the better. This may lead to premature valve damage or even accidents.