BAPI BA/H320-O-WP Overview
The BAPI BA/H320-O-WP is an outside air humidity transmitter with a ±3% RH capacitive polymer sensor, a 4 to 20 mA humidity output, housed in a cast aluminum Weatherproof (WP) enclosure rated NEMA 3R.
BAPI calibrates its humidity transmitters at 10 points from 10 to 90% RH, eliminating field calibration. The humidity sensor sits in a 1 in. diameter probe below the enclosure, protected by a replaceable 80 micron sintered stainless steel filter.
The 4 to 20 mA humidity output is loop powered from 10 to 35 VDC and spans 0 to 100% RH.
The weatherproof (WP) enclosure is cast aluminum and rated NEMA 3R, protecting against falling dirt, rain, sleet and snow.
Specifications verified against BAPI Outside Air Units datasheet Rev. 10/06/25, BAPI installation instructions 49483 rev. 10/06/25 and BAPI enclosure styles application note Rev. 05/02/23. Last reviewed by ZOT Supply on November 3, 2026.
Best For
- Controllers with 4 to 20 mA analog inputs for outdoor humidity
- Outdoor humidity measurement where outdoor air temperature is already sensed separately
- DC-powered 4 to 20 mA current loops (10 to 35 VDC)
- Outdoor locations needing NEMA 3R protection against rain, sleet and snow
Warranty
BAPI warrants its products to be free from defects in materials and workmanship for five years from the date of sale.
Key Features
10-Point Calibration
Calibrated at 10 points from 10 to 90% RH, eliminating field calibration.
4 to 20 mA Humidity Output
Loop-powered 4 to 20 mA humidity output for 0 to 100% RH on a 10 to 35 VDC supply.
Cast Aluminum NEMA 3R Enclosure
Weatherproof (WP) cast aluminum enclosure rated NEMA 3R, IP24.
Replaceable Sintered Filter
80 micron sintered stainless steel filter unscrews for cleaning; replacement part BA/HDOFS3.
Reverse Polarity Protected
The humidity transmitter is polarity sensitive and reverse polarity protected.
ZOT Supply is an authorized distributor of BAPI products.
Technical Specifications
| Humidity | |
|---|---|
| Sensor | Capacitive polymer |
| Accuracy | ±3% RH (10 to 90% RH @ 25°C), non-condensing |
| Calibration | 10 points from 10 to 90% RH |
| Drift | 0.5% per year |
| Response Time | < 5 seconds in moving air |
| RH Linearity | Negligible, factory corrected linear from 10 to 80% RH |
| RH Hysteresis | Factory corrected to <1% |
| Output | 4 to 20 mA at 0 to 100% RH |
| Low RH Behavior | Output goes to its maximum value if humidity drops to 5% RH or below |
| Output Load | 700 Ω @ 24 VDC; max load impedance = (supply VDC - 10 VDC) / 0.02 A |
| Wiring | Red: power; Black: 4 to 20 mA humidity output to controller analog input; White: not used |
| Power | |
| Supply | 10 to 35 VDC, 22 mA max (loop powered) |
| Physical | |
| Probe | 2.4 in. below enclosure, 1 in. diameter |
| Filter | 80 micron sintered stainless steel, replaceable (BA/HDOFS3) |
| Enclosure | Weatherproof (WP) |
| Enclosure Material | Cast aluminum |
| Enclosure Rating | NEMA 3R, IP24 |
| Enclosure Dimensions | 2.75 x 4.5 x 2.2 in. (70 x 114 x 55 mm), W x H x D |
| Mounting Seal | Foam on the back of the unit |
| Termination | Open wire; 18 to 26 AWG with sealant filled crimp connector (BA/SFC1000-x00) or 26 to 16 AWG with sealant filled wire nut (BA/SFC2000-x00) |
| Wiring Practice | Twisted pair, 22 AWG minimum; do not run in the same conduit as AC power wiring |
| Environment and Compliance | |
| Operating Range | -40 to 158°F (-40 to 70°C), 0 to 100% RH |
| Compensation | Fully temperature compensated |
| Agency | CE EN 61326-1:2013 EMC (Industrial Electromagnetic Environment), RoHS |
| Warranty | 5 years from date of sale |
Documentation
Frequently Asked Questions
What is the BAPI BA/H320-O-WP?
The BAPI BA/H320-O-WP is an outside air humidity transmitter with a ±3% RH capacitive polymer sensor, a 4 to 20 mA humidity output, housed in a cast aluminum Weatherproof (WP) enclosure rated NEMA 3R.
What power supply does the BAPI BA/H320-O-WP need?
The BAPI BA/H320-O-WP runs on 10 to 35 VDC with 22 mA max current draw, loop powered through the 4 to 20 mA humidity output.
How accurate is the BAPI BA/H320-O-WP?
Humidity accuracy is ±3% RH (10 to 90% RH @ 25°C), non-condensing.
How do I convert the 4 to 20 mA output to percent RH?
Use %RH = (mA - 4) / 0.16. The output spans 0 to 100% RH.
Is the weatherproof (WP) enclosure watertight?
No. The cast aluminum Weatherproof (WP) enclosure is rated NEMA 3R: protected against falling dirt, rain, sleet and snow, and undamaged by external ice formation. Where it is exposed to driving rain, sprinkler systems or jets of water, it may need a 3/16 in. weep hole drilled in the lowest horizontal face.
Does an outdoor sensor need a weather shade?
Radiant heat from building surfaces and parking lots affects outdoor temperature and humidity sensors. The BAPI Weather Shade blocks that radiant heat, improving sensor accuracy.
Where should an outside air humidity sensor be mounted?
Mount it in a permanently shaded area away from windows and doors, out of direct sunlight, with the sensor probe pointed down. Seal the wiring hole with caulk after wiring, and terminate with sealant filled connectors.
- Sensor Type:
- Outside Air
- Humidity Element:
- 3%
- Output Signal:
- 4-20mA
- Temperature Element:
- None
- CO2 Element:
- None
- Display:
- No Display
- VOC Element:
- None
- Probe Length:
- 2.4
- Enclosure:
- NEMA 3R Enclosure
- Supported Protocols:
- None
