Phone: 253-927-6186
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HD2903T - HD29V3T series Air speed transmitters
HD2937T - HD29V37T series Temperature, Air speed transmitters
HD29371T - HD29V371T series Temperature, Relative Humidity and Air speed transmitters
The HD29 series of transmitters are used for controlling air speed for conditioning and ventilation applications (HVAC/BEMS) in the following sectors: pharmacy, museums, clean rooms, ventilation ducts, crowded places, canteens, auditoria, gyms or high-density farms, as well as industrial and civil sectors.

Airspeed Humidity Transmitter - Indicator

Model  Description 
HD2903  Temperature, Relative Humidity and Air speed transmitters

The sensors in combination with an accurate electronics guarantee precise and reliable measurements in the course of time. The thin fi lm sensor for air speed, the AISI304 probe sheath, the 20μ metal grid filter for Relative Humidity enable their usage even for hostile applications. The probes are available in three different lengths.

There are two possible installations: in the TO version, the horizontal probe is joined to the electronics
enclosure while in the TC version the probe is connected to the electronics through a cable. In the TO
version, the duct probe is fixed to the electronics enclosure and it is available in three different lengths.

To fix the probe to the duct, you can use, for example, the HD9008.31 flange, a 3/8" universal biconical
connection or a PG16 metal cable gland (Φ 10 - 14mm). In the TC version, the probe together with the
sensors is equipped with a cable which can be 2, 5 or 10 meters long.

Air speed transmitter specifications
Air speed
Measuring range 
The measuring range can be
selected by dip-switch.
Air speed Accuracy
range 0…1m/s
range 0…2m/s
range 0…10m/s
range 0…20m/s 
±(0.04m/s+2% of measurement)
±(0.04m/s+2% of measurement)
±(0.2m/s+3% of measurement)
±(0.2m/s+3% of measurement) 
at 50%RH and 1013hPa 
Temperature Measuring range  -10…+60°C  HD2937, HD29V37, HD29371
and HD29V371 models 
Temperature Accuracy  ±0.3°C 
Relative Humidity Measuring range  5…98%RH  HD29371 and HD29V371
Relative Humidity Accuracy  ±2% (5..90%RH),
±2.5% remaining range 
Relative Humidity Output Range  0…100%RH 
Output (according to the models)  4…20mA
RL < 500Ω
RL > 10kΩ 
Power supply  16…40Vdc or 12…24Vac±10%   
Response time
(selected by jumper) 
Operating temperature

-30…+100° C 
Compensation temperature  0…+80°C   
Storage temperature  -10…+70°C   
Electronics protection class  IP67   
Sensor working conditions  Clean air, RH<90%   
Case dimensions  80x84x44  Without probe 
Model  Output  Input 
  4 - 20mA  0 - 10Vdc  Air speed  Temperature  Relative Humidity 
HD2903T...  X   X    
HD29V3T...    X X    
HD2937T...  X   X X  
HD29V37T...    X X X  
HD29371T...  X   X X X
HD29V371T...    X X X X
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Hotek Technologies, Inc
tel: 253-927-6186