All valves have some type of control mechanism. For valves that turn the flow of the media on and off based on the needs of the system operator, valves have an external control. This external control may be a lever, push button, knob, or handle. There is also the option to consider a toggle valve, which is an ideal option for a pneumatic system where air flow has to be either on or off.
The Toggle Valve
The pneumatic toggle valve is only used to either allow air flow through the valve or to shut it off. This is not a flow control valve, and it has no ability to regulate the flow of the air through the valve body.
It is not uncommon for a pneumatic toggle valve to be used to start the flow of air through the system, and for another valve, such as a needle valve, to be used to fine tune the flow of air. This is commonly seen on the suction and vacuum types of systems in dental offices. It can also be used on compressor lines and systems to initiate air flow. In these instances, a check valve can be used in tandem with the toggle valve to prevent any backflow if the upstream pressure drops during use.
NO or NC
One of the important choices in finding the correct pneumatic toggle valve, other than the correct sizing of the valve for the lines, is the choice of a normally open (NO) or normally closed (NC) design. The normally open valve allows air flow when the toggle is in the “on” position, while the normally closed valve prevents air flow until the toggle is switched to the opposite position.
Other factors to consider include the style of the ports. These can range from threaded to barbed, with the type of hose or component connected to the valve a key factor in this decision.