Hazardous Area Humidity Assembly
Overview Specifications
Humidity: 4 to 20 mA DC = 0% to 100% RH.
Temperature: 4 to 20 mA DC over specified range (optional) Models AH71_, AH72_, and AH73_ series are 2-wire tempera-ture compensated
humidity transmitters that are FM and CFM
approved for use in hazardous locations. Intrinsically safe mod-
els are available with an optional
temperature transmitter out-
put. The AH73 is also available with an optional digital display
for remote indication of relative humidity and temperature.The transmitters utilize a thin film capacitive humidity sensorwhich provides outstanding sensitivity and chemical robustness.
The transmitter converts the
humidity sensor’s signal into a 4 to
20 mA DC current, which changes proportionally from 4 mA at
0% RH to 20 mA at 100% RH. The optional temperature loop
produces a second 4 to 20 mA DC output where the current
changes from 4 mA at the lowest temperature of the range, to
20 mA at the top of the temperature range. The leads that supply power also carry the current signal.•Accuracy of ±2.5% RH
•Temperature compensated
•Temperature output option
•Two-point field calibration
•NIST traceable calibrations Output(s): Humidity Range: 0 – 100% RH Sensing Element: Humidity: Thin film capacitive element.
Temperature: 1000 ohm platinum RTD, 0.00385 TCR Temperature Effect: ±0.03% RH/°C ±1% from 10°C to 85°C Operating Temperature: Transmitter:-40 to 17 6 °F (-40 to 80°C), non-condensing.-4 to 17 6 °F (-20 to 80°C), non-condensing, model AH73.Sensor:-40 to 302°F (-40 to 150°C). Storage Temperature: -58 to 185°F (-50 to 85°C), non-condensing. Supply voltage: 9.5 to 28 VDC for intrinsically safe (IS) models.1 6 .5 to 28 VDC for explosionproof (XP) models. Voltage effect: ±0.001% of span/volt from 9.5 to 28 VDC. Loop resistance: The maximum allowable resistance of the signal-carrying loop, including extension wires and load resistors, is given by this formula: IS: R
Applications
Building automation systems (HVAC), hospitals, food storage,warehouses,
clean rooms, pharmaceutical,
drying equipment,
and emissions monitoring.
loopmax = (V
supply - 9.5)/0.02 AMPS. For example, if supply volt-age is 24 VDC, the loop resistance must be less than 725 Ω .XP: R
loopmax = (V
supply - 1 6 .5)/0.02 AMPS. For example, if supplyvoltage is 24 VDC, the loop resistance must be less than 375 Ω .
Specifications subject to change Page 9-10
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