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Standard Humidity Probes
Precon offers the following products for the building control
industry. They are available in current form in small and
large volumes and can also be customized for a specific
application.

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HW Series
5% RH
Sensor/Transmitter
3% Humidity Transmitter & Optional Temperature
Transmitters |
Model H-31K 3% Air Humidity Transmitters are
specifically designed for user in HVAC/BAS applications.
These instruments measure relative humidity from 0% to 100%.
The standard two-wire, 4-20 mA output provides low cost
humidity monitoring for building control. The RH transmitter
is available with thermistor or RTD temperature sensors or a
4-20 mA rangeable temperature transmitter. H-31K
models available in room, duct, and OSA mounting styles. |
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FEATURES |
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0% to 100% RH measurement
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±3% accuracy (5% to 95% RH)
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Two-Wire, 4-20 mA output
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White plastic design
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SPECIFICATIONS |
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Sensing Element
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Capacitive Polymer
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Transmitter
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4-20mA, 675ohm @
24V (HD31K & HO31K only) |
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Accuracy |
±3% RH @ 77°F (25°C), 5%
to 95% RH |
Supply Voltage |
18 - 35 VDC |
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Temp Effect |
Temperature
compensated with 0.005% RH per
°F (0.01%
per °C) |
Ambient temp |
-20°
to 140°F (-28° to 60°C) |
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Long-term
stability |
<±1%
drift per year, typcial |
Storage temp |
-58°
to 185°F (-50° to 85°C) |
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Output humidity |
Two-wire, loop-powered,
4-20 mA = 0% to 100% RH linear |
Max load
impedance |
(Supply voltage -
12 VDC) /0.02
i.e. 600ohm@24VDC |
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Output temp |
Two-wire, loop-powered,
4-20 mA |
Connections |
Screw terminals for
loop termination |
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Temp range
limits |
-30° to 250°F (-34° to
121°C), min span of 40°F (22°C) |
Enclosure |
White plastic |
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Optional temp
Thermistor |
Type 3, 21, 22, 24, 27, 42 |
Weight |
1.2 lb (0.55 kg) |
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RTD |
Type 81, 85, 91 |
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HD
Series
3% Duct / Outside Air
RH Sensor / Transmitter |
Model
HD30K Duct and HO30K Outside Air Humidity Transmitters
have been specifically designed for use in HVAC/BAS
applications. These instruments measure relative humidity
from 0% to 100%. The standard two-wire, 4-20 mA output
provides low cost duct and outside air monitoring for
building control. Both duct and outside air RH transmitters
are available with thermistor or RTD temperature sensors or
with a 4-20 mA rangeable temperature transmitter. |
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FEATURES |
- 0% to 100% RH measurement
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±3% accuracy (5% to 95% RH)
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Two-wire, 4-20 mA output RH
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Optional temperature thermistor
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Optional temperature RTD
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Optional temperature 4-20 mA
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SPECIFICATIONS |
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Sensing Element
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Capacitive Polymer
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Operating temp
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-20°
to 185°F
(-28° to 60°C) |
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Accuracy |
±3% RH @ 77°F (25°C), 5%
to 95% RH |
Storage temp |
-58°
to 185°F
(-50° to 85°C) |
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Temp Effect |
Temperature
compensated with less than 0.005% RH per
°F (0.01%
per °C) |
Max load
impedance |
(Supply voltage -
10 VDC) /0.02
i.e. 700 ohm @ 24 VDC |
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Long-term
stability |
Less than
±1%
drift per year, typcial |
Connections |
Screw terminals for
loop termination |
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Output humidity |
Two-wire, loop-powered,
4-20 mA = 0% to 100% RH linear |
Enclosure |
Single-gang,
pressure-cast aluminum weatherproof box with gasketed cover |
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Supply Voltage |
18-35 VDC |
Weight |
1.20 lb (0.55 kg) |
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Operating range |
0% to 100% RH, 4-20 mA |
Optional temp |
Thermistor type 3, 21, 22,
24, 27, 42 RTD type 91, 81 4-20 mA, 650ohm @ 24V |
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KHR Series
3% Duct / Outside
Air RH & temperature Sensor / Transmitter |
Models KHR and KHD are low cost,
general-purpose humidity transmitters that utilize
capacitance technology. Wide range and good accuracy make
these ideal humidity transmitters for locations where
±5% RH
readings are required. The sensors are designed for indoor
applications where relatively stable temperature conditions
exist. The sensors should not be exposed to vapors, such as
acetone, that attack plastics. |
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FEATURES |
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Fast response
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Accuracy ±5%
10% to 90%
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Humidity span 0% to 100%
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4-20 mA signal
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Highly stable
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One-year warranty
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SPECIFICATIONS |
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Output range
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0% to 100% |
Operating temp
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32°
to 122°F (0° to 50°C), 0% to 100% RH, noncondensing |
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Accuracy |
±5% (10% to 90% RH) |
Transmitter
output |
4-20 mA, DC two-wire (0%
to 100%) |
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Linearity |
±3% |
Power
requirement |
18-35 VDC |
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Hysteresis |
3% (10% to 90% RH) |
Max external
load |
600ohm @ 24 VDC |
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Temp dependence |
0.2% RH per °C |
Weight |
1 lb (0.45 kg) |
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Precon’s package includes:
Low Cost OEM supplier
Six-Sigma quality testing standards
Standard and custom products
Fast response time
Volume production capability
35 years of manufacturing experience
Made in the USA
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Applications |
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Food
Processing Equipment
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Pool and
Spa Systems
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Industrial
Process Control
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Remote
System Monitoring
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Semiconductor Fabrication
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Commercial
Equipment
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Building
Automation
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