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HD404T / HD404ST Series – Low Pressure Transmitters
Brand: Delta OHM S.R.L.The series of HD404T transmitters is able to measure relative pressures with reference to the atmosphere or differential in the range
- From 50 to 1000 Pa (from 0.2” H2O to 4” H2O) for the versions with analog output
- 250 Pa / 1000 Pa / 100 mbar for the versions with RS485 Modbus‑RTU output.
The series uses a silicon “micro‑machined” type sensor compensated in temperature that has an excellent linearity, repeatability and stability over time.
The output signal from the sensor is amplified and converted, depending on the model, into a standard current analog output (4-20 mA) and a voltage analog output (0-10 V), or into a digital RS485 Modbus‑RTU output, which, then, can be transmitted over long distances with a high immunity to noise.
In the models with analog output it is possible to choose, via a dip switch, between two measurement ranges in order to select the optimal scale for each application.
Features- Wide variety for any application
- Great flexibility
- Highly accurate & Reliable system
- Immediate & Direct reading
- Easy to set up & Quick to install
Specifications
Brand
Sensor
- Piezoresistive
Resolution
- 1 Pa for f.s. 1000 Pa
- 0.1 mbar for HD404ST5
- 0.05 mmH₂O for f.s. up to 50 mmH₂O
- 0.1 mmH₂O for f.s. 100 mmH₂O
- 0.002” H₂O for f.s. up to 4” H₂O
- 0.01 m/s (only SR versions)
- 0.1 Pa for HD404ST2
- 0.5 Pa for f.s. up to 500 Pa (except HD404ST2)
Output
- HD404T: active analog 0 to 10 Vdc (RLmin =10 kΩ) or 4-20 mA (RLmax = 500 Ω)
- HD404ST: digital RS-485 Modbus-RTU
Response Time
- HD404T with dip-switch set to FAST: 0.125 s in pressure mode 1 s in speed mode (only SR versions)
- HD404T with dip-switch set to LOW: configurable 1, 2 or 4 s (default 2 s)
- HD404ST configurable 0.125, 1, 2 or 4 s (default 2 s)
Overpressure Limit
- 50 kPa
Connection to PC
- HD404T: RS-232 serial port can be connected to a USB port by using the optional CP27 adapter
- HD404ST: can be connected to a USB port by using the optional RS48 adapter
Zero Calibration
- Automatic for the versions with AZ option
Compatible Media
- Only air and non-aggressive dry gases
Power Supply
- HD404T: 24 Vac ± 10 % or 18…40 Vdc
- HD404ST: 12 to 30 Vdc
Absorption
- HD404T: < 1 W @ 24 Vdc
- HD404ST: < 100 mW @ 12 Vdc
Pressure Connection
- Nickel-plated brass, Ø 6 mm
Electrical Connections
- Screw terminal block, max. 1.5 mm2 , PG9 cable gland
Operating Conditions
- -10° C to 60° C (-5° C to 50° C for the models with AZ option), 0 to 95 % RH
Protection Degree
- IP65
Storage Temperature
- -20° to +70° C
- Clean Room Monitoring
- Filter Control
- Flow Measuring
- Air Conditioning Control
- Ventilation Control
