Valves are control components in fluid transportation systems, with functions such as shutting off, regulating, diverting flow, preventing backflow, stabilizing pressure, branching, or relieving overflow.
In general, most valves close clockwise and open counterclockwise, or you could say left to open, right to close. Let’s first go over some basic valve operation knowledge: since most people are right-handed, it’s easier to turn clockwise than counterclockwise with the right hand. So, from both energy-saving and safety perspectives, opening counterclockwise and closing clockwise is relatively more reasonable.
Valves with handwheels often have direction arrows or O→S markings (O for Open, S for Shut).
Are all valves clockwise to close?
There are actually exceptions! For example, pressure-reducing valves on oxygen, hydrogen, and nitrogen cylinders open clockwise and close counterclockwise. High-pressure oxygen cylinder angle valves open clockwise and close counterclockwise; the outlet pressure-reducing valve increases pressure by turning clockwise and decreases pressure (closes) by turning counterclockwise. The back of the cylinder outlet is equipped with a safety device. When using oxygen, turn the handwheel counterclockwise to open the oxygen valve. When the handwheel rotates, the stem rotates as well, which then moves the valve through a switch plate, causing the valve to move up or down. When the valve moves up, it opens the cylinder and allows gas to flow out of the outlet. When the valve moves down and presses tightly, the valve closes completely due to the nylon valve seat inside. The valve movement range is 1.5–3mm.
Working principle: An oxygen inhalator is made up of a pressure gauge, a pressure-reducing valve and safety valve, a flow meter, a flow control valve, and a humidifier bottle. High-pressure oxygen is reduced by the pressure-reducing valve, turning from high-pressure to low-pressure oxygen. It then passes through the flow meter into the humidifier bottle. After humidification, it flows out through the low-pressure output to supply oxygen to the patient, with the flow rate adjustable by the flow controller.
Also, some special valves like slide valves and butterfly valves, due to their installation positions, may open clockwise and close counterclockwise.
Special valves are usually reversed, so you need to pay attention when operating them. Improper installation means operators must observe these details carefully. Details determine success—carelessness is not allowed. Special valves are generally marked at visible locations with operating directions, and some places even post operational procedures at the special valve sites to prevent misuse.
