BAPI BA/3K-H310-O-WP Overview
The BAPI BA/3K-H310-O-WP is an outside air humidity transmitter with a ±3% RH capacitive polymer sensor, a 0 to 10 VDC humidity output and a passive 3K thermistor for outdoor air temperature, 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 0 to 10 VDC humidity output spans 0 to 100% RH, powered from 15 to 35 VDC or 15 to 27 VAC. A separate passive 3K thermistor (Yellow/Black leads) gives the controller a resistance input for outdoor air temperature.
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 0 to 10 VDC analog inputs for outdoor humidity
- Controllers with 3K thermistor temperature inputs
- Panels supplying 15 to 35 VDC or 15 to 27 VAC
- 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.
0 to 10 VDC Humidity Output
0 to 10 VDC humidity output for 0 to 100% RH, powered from 15 to 35 VDC or 15 to 27 VAC.
Passive 3K Thermistor
Separate 3K thermistor for outdoor air temperature, accurate to ±0.36°F (0.2°C) from 32 to 158°F (0 to 70°C). Leads are Yellow/Black and are not polarity sensitive.
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 | 0 to 10 VDC at 0 to 100% RH |
| Low RH Behavior | Output goes to its maximum value if humidity drops to 5% RH or below |
| Output Impedance | 10 kΩ |
| Wiring | Red: power; White: humidity output to controller analog input; Black: common (ground for power and humidity output) |
| Power | |
| Supply | 15 to 35 VDC, 6 mA max; 15 to 27 VAC, 0.53 VA max |
| Temperature Sensor | |
| Element | Passive 3K thermistor |
| Accuracy | ±0.36°F (0.2°C) from 32 to 158°F (0 to 70°C) |
| Lead Wire Colors | Yellow/Black (not polarity sensitive) |
| Output | Resistance |
| 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/3K-H310-O-WP?
The BAPI BA/3K-H310-O-WP is an outside air humidity transmitter with a ±3% RH capacitive polymer sensor, a 0 to 10 VDC humidity output and a passive 3K thermistor for outdoor air temperature, housed in a cast aluminum Weatherproof (WP) enclosure rated NEMA 3R.
What power supply does the BAPI BA/3K-H310-O-WP need?
The BAPI BA/3K-H310-O-WP runs on 15 to 35 VDC (6 mA max) or 15 to 27 VAC (0.53 VA max). Power requirements depend on the humidity output type.
How accurate is the BAPI BA/3K-H310-O-WP?
Humidity accuracy is ±3% RH (10 to 90% RH @ 25°C), non-condensing. The 3K thermistor is accurate to ±0.36°F (0.2°C) from 32 to 158°F (0 to 70°C).
How do I convert the 0 to 10 VDC output to percent RH?
Use %RH = V / 0.1. 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:
- 0-10 VDC
- Temperature Element:
- 3K
- CO2 Element:
- None
- Display:
- No Display
- VOC Element:
- None
- Probe Length:
- 2.4
- Enclosure:
- NEMA 3R Enclosure
- Supported Protocols:
- None
