Introduction
This is a 3D model of a Three-Way Transfer Valve.
3D Model Annotations
Three-Way Transfer Valve
This valve is a three-way transfer valve used for transferring a pneumatic supply from one line to another should the signal pressure decrease below a given set point.
Common Port (C)
The common port is connected to the main pneumatic supply line to the valve; it is pressurised irrespective of the three-way valve’s outlet position.
Normally Open (NO)
The term ‘normally open’ refers to the position of the valve when pressure from the signal port is no longer present. In the event of pressure reduction from the signal port, the NO port will be uncovered, and flow will go from the C port to NO port.
Normally Closed (NC)
The term ‘normally closed’ refers to the position of the valve when pressure from the signal port is present. If pressure from the signal port (C) is present, the NC port will be uncovered, and flow will go from the C port to NC port.
Spring
A spring maintains pressure upon the diaphragm installed directly below it. Pressure acting upon the diaphragm causes it to either raise or lower, depending upon if the spring pressure is exceeded by the signal port pressure, or not. Movement of the diaphragm will either allow flow to the normally open port, or to the normally closed port.
Adjusting Bolt
Tightening or loosening the adjusting bolt will increase or decrease (respectively) the lifting pressure of the diaphragm.
Locking Nut
A locking nut ensures the adjusting bolt does not become loose over time; loosening of the adjusting bolt would lead to the diaphragm lifting at a lower pressure.
Double Faced Plug
The position of the double-faced plug will vary depending upon if pressure from the signal port is present, or not. In the event of a reduction of pressure from the signal port, the spring pushes down upon the plug, closes the NC port, and opens the NO port.
Signal Port (S)
The signal port is connected to a sealed space below the diaphragm. If the signal port pressure drops below a given set-point, the spring acting upon the diaphragm will push it downwards, which causes the NO port to be uncovered, and the NC port to be covered.
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Additional Resources
https://www.industrialspec.com/about-us/blog/detail/three-way-ball-valve-t-port-l-port-flow-patterns