Pressure switches
Pressure switches can be used to supervise and control systems that use pressurised fluids. They close an electrical contact when a certain media pressure has been reached.
The switch can be designed to make contact on pressure rise and pressure fall. This pressure can be set; for example, a pressure switch can be set to open at 1.6 Bar and to close at 1.8 Bar.
In a normally open variant of a pressure switch, the incoming pressure will pass through the connection port and act on the diaphragm.
If the incoming pressure is greater than the set pressure value, then the plunger will move the diaphragm and close the circuit between the contacts. When the pressure falls below the set pressure, the diaphragm will move away and the switch will open again.
A normally closed configuration works in reverse so, the diaphragm would be opened by the incoming pressure, if it meets the set pressure point, and closed by a fall in pressure.
Examples of the different uses of a pneumatic pressure switch:
- Switch a household well water pump automatically when water is drawn from the pressure tank.
- Switching off an electrically driven gas compressor when a set pressure is achieved in the reservoir.
- Switching off a gas compressor, whenever there is no feed in the suction stage.
- In-cell charge control in a battery.
- Switching On/Off an alarm light in the cockpit off an aircraft, if cabin pressure (based on altitude) is critically low.
- Air filled hoses that activate switches when vehicles drive over them. Common for counting traffic and at petrol stations.
There are other types of pressure switches: Mechanical,
electric, hydraulic and differential pressure switches are all available.
Mechanical pressure switches detect mechanical force.
A
pressure sensitive mat will provide a contact signal when force is applied to
it.
The signal that is sent from the mat can vary, depending on the type of
mat, some mats will provide a single signal that will notify you that there is
pressure being applied where as some other mats would be able to tell you the
exact location that the pressure is being applied to on the mat.
An example of a use
of a mechanical pressure switch would involve a pressure sensitive mat that
could be used to automatically open doors on commercial buildings.
Sensors like
this are also used in alarm applications such as pressure sensitive floors.
Another use for
pressure sensitive mats would be as part of an interlock system to ensure
machine operations are clear of dangerous areas of a process before it
operates.
An electronic pressure switch incorporates some variety of pressure
transducer, and will also contain an internal circuit to compare the measured
pressure to a set point.
An electronic pressure switch could potentially offer
the benefits of improved repeatability, accuracy and precision over a
mechanical switch.
Hydraulic pressure switches are used throughout vehicles.
They are generally used to warn if an engines oil pressure falls below a safe
level, or can be used to control automatic transmission torque converter lock
up.
Modern
cars will use a pressure switch to activate the brake lights directly from the
brake pedal.
V-Flow solutions offer a wide range of high quality - high spec pressure switches.
V-Flow Solutions also offer a wide range of Ashcroft switches, ranging from electric, temperature and differential pressure switches. Available for a wide range of applications and ATEX certified.
You can view our range of ATEX Pressure and temperature switches here:
You can read the rest of V-Flows blogs here.
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V-Flow solutions offer a wide range of high quality - high spec pressure switches which can be found here, on our website:
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