How can you differentiate a pressure switch from a vacuum switch?
The pressure the vacuum switches are so identical that you can sometimes fail to identify them. But the system in which they are used is quite different.
Differentiating a pressure switch and a vacuum switch is not as complex as it might seem. The Presair switch is one of its kind as it can sense the presence of pressure and yet detect the presence of a vacuum. In other words, it can be used to detect one of the two. Inside the Presair switch, there is a rubber diaphragm as well as two air ports. These air ports are on both sides of the diaphragm where one is on top while the other is below. For the switch to open or close, the diaphragm must be forced against the mechanism of the switch.
In the pressure switch, the air is forced against the diaphragm until it moves to make contact thus completing the electric circuit. This triggers the switch to take action as required.
When it comes to a vacuum switch, the mechanism is just the same. The only difference is that instead of air pushing the diaphragm, instead, it pulls it from the opposite air port. The same amount of force is needed to trigger the switch as it does not matter whether it is pressure or vacuum.
So the mechanism works by either pulling or pushing the diaphragm. The air pressure pushes the diaphragm up while the vacuum sucks the diaphragm down. This what differentiates a vacuum switch from a pressure switch.
An example of a pressure application
A good example of pressure application can be the process of monitoring the amount of liquid within the reservoir as the reservoir is filled with water, there is less space for air in the tank, as a result, it increases pressure. when the amount of pressure needed is reached it will push the diaphragm then the switch is triggered to take the intended action.
An example of a vacuum application
Lifting a sheet of glass using suction mechanism can be an idle example for a vacuum application. To move a sheet of glass an air suction is used to raise and lower the sheet. The vacuum switch is responsible for monitoring the amount of suction force that is needed in every movement then alert the controller as the sheet is raised or lowered.