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Humidity and temperature sensing for hazardous or explosionproof locations
 Models AH71, AH72, and AH73 are 2-wire temperature compensated humidity transmitters that are FM and CFM approved for use in hazardous locations. Intrinsically safe models are available with an optional temperature transmitter output. 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 sensor which 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
- One-point field calibration
- NIST traceable calibrations
Applications: Building environmental control systems (HVAC), hospitals, food storage, warehouses, clean rooms, pharmaceutical, freezers, drying equipment, and emissions monitoring.
Specifications |
| Output(s):
Humidity: 4 to 20 mA DC = 0% to 100% RH.
Temperature: 4 to 20 mA DC over specified range (optional)
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 176°F (-40 to 80°C), non-condensing.
-4 to 176°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.
16.5 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: Rloopmax = (Vsupply - 9.5)/0.02 AMPS. For example, if supply voltage
is 24 VDC, the loop resistance must be less than 725 Ω.
XP: Rloopmax = (Vsupply - 16.5)/0.02 AMPS. For example, if supply
voltage is 24 VDC, the loop resistance must be less than 375 Ω.
Accuracy: Includes linearity, hysteresis, repeatability, and
voltage effects.
Humidity: ±2.5% from 10% to 80% RH @ 25°C, ±3.5% from
80% to 90% RH @ 25°C.
Temperature: ±0.5°F(0.27°C) @ 77°F (25°C) or +/- 0.75% of span,
whichever is greater.
Adjustments: Zero and Span field adjustments, non-interacting.
Time Constant: 50 seconds in slow moving air.
Connections: Screw terminals (22-14 AWG wire).
Weight:
AH71_ 2.84 lbs (1.29 kg).
AH72_, AH73_ 4.46 lbs (2.02 kg).
Min. output current: 3.8 mA.
Max. output current: 22 mA.
Filter: 60 micron stainless-steel sintered filter
(replacement P/N : AC103512)
Factory Mutual Approvals:
Explosionproof with intrinsically safe sensor:
Suitable for the following hazardous area locations:
Class I, Division 1, 2, Groups B, C, D
Class II, Division 1, 2, Groups E, F, G
Class III, Division 1, 2
Intrinsically safe installation:
Suitable for the following hazardous area locations:
Class I, Division 1, 2, Groups A, B, C, D
Class II, Division 1, 2, Groups E, F, G
Class III, Division 1, 2
Class I, Zone 0, AEx ia IIC T4
Transmitter entity parameters:
Vmax = 28 volts; Imax = 100 mA; Ci = 0.037 μF and Li = 0 mH.
Transmitter Ranges:
| Code |
Transmitter Range |
| NT |
No Temperature Transmitter |
| EN |
-20°F to 140°F |
| S |
0°F to 100°F |
| A |
20°F to 120°F |
| BI |
30°F to 130°F |
| N |
32°F to 122°F |
| H |
40°F to 90°F |
Accessories:
Sintered Filter Replacement - Part Number: AC103512
Slotted Filter Replacement - Part Number: AC103513
Pipe Mounting Kit for AH72/AH73 -Part Number: AC102765
Wall Mounting Kit for AH71 - Part Number: AC103168
Duct Mounting Kit for AH71 - Part Number: AC103253
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How To Order |
| AH73 |
Model number
AH71 Industrial grade humidity transmitter with
optional temperature transmitter,
CH106 connection head, display NA
AH72 Industrial grade humidity transmitter with
optional temperature transmitter,
XIHMF connection head, display NA
AH73 Industrial grade humidity transmitter with
optional temperature transmitter,
XIHMFG connection head, display available
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| 1 |
Probe Diameter:
1 = 0.375" |
| 1 |
Process Threads:
1 = 1/2" NPT
2 = G1/2 |
| P3 |
Conduit thread:
P3=1/2" NPT
P4=3/4" NPT |
| L120 |
Probe length:
L60 = 6"
L120= 12" |
| T1 |
Filter type:
T1= Sintered stainless steel
T2= Slotted stainless steel |
| HT480 |
Transmitter model number:
HT480 = Explosionproof with intrinsically safe sensor
(transmitter code NT only)
HT490 = Intrinsically safe |
| N |
Display:
C = Display, metric units (AH73_series only)
F = Display, English units (AH73_series only)
N = No display (AH71_ and AH72_ series only) |
| 1 |
Signal output:
1 = 4 to 20mA |
| N25 |
Calibration accuracy (humidity transmitter)
N25 = ±2.5% from 10% to 80% (25°C)
with NIST certificate
S25 = ±2.5% from 10% to 80% (25°C) |
| S |
Temperature transmitter range from table |
| AH7311P3L120T1HT480N1N25S = Sample part number |
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