Pressure switch or pressure sensor - which one when?
A pressure switch gives a switching signal (on/off) at a set point with hysteresis. A pressure sensor or transmitter gives a continuous signal proportional to pressure - analog as 4-20 mA or 0-10 V, or digital via IO-Link. The choice depends on whether one switch point is enough or the pressure has to be measured.
View pressure switches & sensorsWhat is the difference between a pressure switch and a pressure sensor?
A pressure switch monitors a pressure and gives a switching output (on/off) as soon as a set point is reached - mechanically via a diaphragm and spring, or electronically. A pressure sensor or transmitter measures the pressure continuously and gives a continuous signal proportional to pressure. The switch answers "pressure reached - yes or no?", the sensor answers "exactly how high is the pressure?".
| Feature | Pressure switch | Pressure sensor / transmitter |
|---|---|---|
| Output | switching signal on/off | continuous 4-20 mA, 0-10 V, IO-Link |
| Use | monitor a limit, switch | measure, display, control |
| Accuracy | switch point with hysteresis | measured value across the range |
How do set point and hysteresis work?
The set point (switch point) is the pressure at which the switch operates. The hysteresis is the difference between the switch-on and switch-back point: it stops the output chattering around the set point on small pressure fluctuations. On electronic switches both are usually freely adjustable.
Pressure at which the output switches - choose to match the application.
ViewWhen a switch, when a sensor - which one when?
A pressure switch is enough when only a limit is monitored - pump on/off, enable only above a minimum pressure, or signal a clogged filter. A pressure sensor is needed when the pressure has to be displayed, logged or controlled, or when a controller needs the measured value.
| Task | Recommendation | Signal |
|---|---|---|
| monitor a limit, switch | pressure switch | on/off |
| display and control pressure | pressure sensor | 4-20 mA / 0-10 V |
| values to controller / PLC | sensor with IO-Link | digital IO-Link |
On accuracy: a pressure switch is only as accurate as its switch point plus hysteresis - it does not measure the value. A pressure sensor outputs the measured value across the whole range; its accuracy depends on the sensor. Clean, prepared air protects both - see Air preparation.
Frequently asked questions
What is the difference between a pressure switch and a pressure sensor?
A pressure switch gives a switching signal on/off at a set point. A pressure sensor measures the pressure continuously and gives a continuous signal, for example 4‑20 mA, 0‑10 V or IO-Link.
What does hysteresis mean on a pressure switch?
Hysteresis is the difference between the switch-on and switch-back point. It prevents the output from switching on and off repeatedly on small pressure fluctuations around the set point.
When is a pressure switch enough and when do I need a sensor?
A pressure switch is enough when only a limit is switched. A pressure sensor is needed when the pressure has to be measured, displayed, logged or controlled.
The right pressure switch or pressure sensor
Pressure switch with a switching output or pressure sensor with analog and IO-Link signal - matched to your application.
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