How to Use Pressure Gauges, Pressure Switches, and Pressure Transmitters by Application

In pump systems, control panels, hydraulic units, compressed air systems, water treatment, and industrial process control, pressure gauges, pressure switches, and pressure transmitters have different functions.

The basic rule is:

Pressure Gauge

A pressure gauge is used for local indication.
It helps operators see the actual pressure on site and compare it with HMI or PLC values.

Typical applications:

• pump discharge pressure indication;

• suction pressure inspection;

• hydraulic pressure display;

• compressed air pressure display;

• filter inlet/outlet local reading;

• commissioning verification.

It does not provide continuous feedback to PLC or VFD unless it is a digital gauge with output.

Pressure Switch

A pressure switch is used for switching, alarm, interlock, and protection.

Typical applications:

• low pressure alarm;

• high pressure trip;

• dry-run protection;

• pump start / stop;

• hydraulic pressure ready signal;

• filter clogging alarm.

It provides an ON / OFF signal, not a continuous pressure value.
Therefore, it should not be used as VFD PID feedback.

Pressure Transmitter

A pressure transmitter converts pressure into a continuous electrical signal, such as 4–20mA, 0–10V, Modbus, or HART.

Typical applications:

• PLC analog input;

• VFD PID feedback;

• HMI pressure trend;

• remote monitoring;

• SCADA integration;

• process pressure control.

For constant pressure water supply, the pressure transmitter is normally the main feedback source for VFD speed control.

Typical Combination

For pump control panels and VFD constant pressure systems, the most reliable configuration is:

pressure transmitter + pressure switch + pressure gauge

NOIKE-AH Application

For pump control panels, constant pressure water supply, booster pump systems, hydraulic units, cooling water systems, water treatment, and industrial process control, NOIKE-AH can provide pressure transmitters, pressure switches, pressure gauges, digital pressure gauges, flow switches, flow meters, temperature sensors, and level sensors.

A practical structure is:

Conclusion

Use:

• pressure gauge for local pressure indication;

• pressure switch for alarm, protection, and interlock;

• pressure transmitter for continuous PLC / VFD feedback;

• differential pressure transmitter / switch for filter clogging, closed tank level, flow, and pressure drop measurement.

The correct selection sequence is:

application → function → indication / protection / control → pressure type → range → output signal → control cabinet input → installation point → commissioning test