


Dwyer Instruments HHT-IU | Intrinsically safe humidity transmitter
A hazardous area humidity/temperature transmitter, the Series HHT, Model HHT-IU, measures temperatures and humidity accurately even in the most hostile conditions. For humidity only, the explosion-proof type has an output of 4 to 20 mA. The temperature and humidity outputs on the intrinsically safe version range from 4 to 20 mA, and in order to comply with hazardous area regulations, an intrinsically safe barrier is needed.

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Accuracy | +/-2% 10 to 90% RH, +/-0.9°F at 72°F (+/-0.3°C at 25°C) |
Approvals | FM, CE |
Connection | Conduit: 1/2" female NPT |
Connection | Electrical: Screw terminal block |
Display Resolution | RH: 0.1% Temperature: 0.1°F (0.1°C) |
Display | Optional 2 line alpha numeric, 8 characters/line. Temperature display is °F/°C selectable |
Drift | <1% RH/year |
Enclosure Rating | NEMA 4X (IP66). Models HHT-EX: FM Explosion-proof, Class I Div. 1 Group B, C, D, Class II Div. 1 Group E, F, G, Class III Div. 1; Models HHT-IX: FM Intrinsically Safe, Class I Div. 1 Group A, B, C, D, Class II Div. 1 Group E, F, G, Class III Div. 1 T4 |
Housing Material | Aluminum |
Hysteresis | +/-1% |
Maximum operating temperature | -40 to 140°F (-40 to 60°C) |
Output Signal | 4 to 20 mA, 2 channels for humidity/temperature models (loop power on RH) |
Power | For intrinsically safe models HHT-IX, 9.5 to 28 VDC. For explosion-proof models HHT-EX, 16.5 to 28 VDC |
Relative Humidity | Range: 0 to 100% RH |
Repeatability | +/-0.1% typical |
Response Time | 15 s |
Sensor Type | Capacitance polymer |
Storage Temperature | -40 to 176°F (-40 to 80°C) |
Temperature Range | -40 to 140°F (-40 to 60°C) |
Temperature Range | Compensated: -4 to 140°F (-20 to 60°C) |
TEMPERATURE SENSOR | Solid state band gap |
Weight | 2 lb 8 oz (1134 g) |
- Explosion-proof and fundamentally safe models with FM approval.
- LCD option integrated.
- Two-way output models for relative humidity and temperature.
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