Reliable pressure monitoring starts with stable readings, especially in HVAC, clean air and dry gas applications where small pressure changes matter. The HD402 series measures relative pressure to atmosphere or differential pressure from 50 Pa to 200 kPa, using a high-stability silicon piezoresistive sensor with temperature compensation.
The series gives you the output format that fits your control system, including 0…10 V, active 0/4…20 mA, 2-wire 4…20 mA, RS485 Modbus-RTU and ON/OFF relay switch versions with SPDT contact. Optional 4-digit LCD indication supports local reading, while relay versions include display, front red LED and internal buzzer for alarm signalling.
Commissioning is straightforward because the instruments are factory-calibrated and ready for use. Configuration can be made by PC connection, dip switches or internal buttons on relay models. The IP65 ABS housing and orientation-independent installation support flexible wall mounting in industrial environments.
The instruments measure relative pressure with respect to atmosphere or differential pressure, depending on installation and model selection.
Analog output models allow selection of full scale and unipolar or bipolar output scaling for the required pressure range.
RS485 versions use Modbus-RTU and support configurable address, baud rate and communication parameters.
Relay switch versions provide an ON/OFF SPDT contact with configurable alarm mode, thresholds, hysteresis and delay settings.
Versions with the L option include a 4-digit LCD for measured parameter indication. Pressure relay switches always include the display.
The transmitter mounts using two Ø3 mm rear holes and can be installed in any position.
Code: HD402 [1] T [2] [3]
Example: HD402ST4L
[1] Output
Blank = voltage and active current analog output
A = 2-wire (current loop) 4…20 mA output
S = RS485 Modbus-RTU output
[2] Nominal full scale (f.s.)
1 = ± 250 Pa / 25 mmH2O / 1 inchH2O / 2,5 mbar
2 = ± 1000 Pa / 100 mmH2O / 4 inchH2O / 10 mbar
3 = ± 10 kPa / 50 mmHg / 1,5 PSI / 100 mbar
4 = ± 100 kPa / 500 mmHg / 15 PSI / 1000 mbar
5 = ± 200 kPa / 1000 mmHg / 30 PSI / 2000 mbar
[3] Display
Blank = without display
L = with LCD display
Code: HD402TR [1] [2]
Example: HD402TR2L
[1] Nominal full scale (f.s.)
1 = ± 250 Pa / 25 mmH2O / 1 inchH2O / 2,5 mbar
2 = ± 1000 Pa / 100 mmH2O / 4 inchH2O / 10 mbar
3 = ± 10 kPa / 50 mmHg / 1,5 PSI / 100 mbar
4 = ± 100 kPa / 500 mmHg / 15 PSI / 1000 mbar
5 = ± 200 kPa / 1000 mmHg / 30 PSI / 2000 mbar
[2] Display
L = with LCD display
