Flow control valves are used on many mechanical, plumbing and gas dispensing apparatuses. The crank valve on a garden hose is a type of flow control valve; the flow of water is regulated by how far the valve is turned in the open direction. Flow control valve adjustments are similar on almost all applications in that opening and closing is achieved by turning in the same direction for most valves. Many specialized valve controls are locked into their set position to prevent the need for constant adjustments.
Loosen, or unlock the adjustment retaining lock on a flow control valve. Use the required key for some locking valves. Turn the locking nut on others by hand or with an adjustable wrench.
Turn flow control valves in the clockwise direction to reduce the flow going through. Turn valve controls to the full clockwise position to close valves temporarily as a reference for reopening them from their closed position. Special flow rate controlling valves on machinery and gas dispensers are not meant to work as a shut-off valve by being left in the off position.
Open a flow control valve by turning it in the counterclockwise direction. Use the recommended number of turns or fractional turn to open the valve for the desired pressure. Set the valve to the desired pressure by turning it to a specific setting, or by measuring with a pressure meter downstream.
Lock, or tighten valve controls with the adjustment retainer. Make hand and wrench adjustments tightly enough to prevent the nut from coming loose under normal use.