![BAPI BA/T1K[20 TO 120F]-O-BB2-TS : 4 to 20 mA Outside Air Transmitter with Terminal Strip, 20 to 120°F, BAPI-Box 2](https://cdn11.bigcommerce.com/s-ksbdsp5vfo/images/stencil/1280x1280/products/89844/135611/BAPI-51-OutsideAirUnits__29970.1787713506.png?c=1 "BAPI BA/T1K[20 TO 120F]-O-BB2-TS : 4 to 20 mA Outside Air Transmitter with Terminal Strip, 20 to 120°F, BAPI-Box 2")
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![BAPI BA/T1K[20 TO 120F]-O-BB2-TS : 4 to 20 mA Outside Air Transmitter with Terminal Strip, 20 to 120°F, BAPI-Box 2](https://cdn11.bigcommerce.com/s-ksbdsp5vfo/images/stencil/500x659/products/89844/135611/BAPI-51-OutsideAirUnits__29970.1787713506.png?c=1 "BAPI BA/T1K[20 TO 120F]-O-BB2-TS : 4 to 20 mA Outside Air Transmitter with Terminal Strip, 20 to 120°F, BAPI-Box 2")
Output4 to 20 mA
Scaled Range20 to 120°F
Power Required12 to 40 VDC
Sensing Element2 wire Platinum, 385 curve
EnclosureBAPI-Box 2 IP66 / NEMA 4
System Accuracy±0.065% of span
BAPI BA/T1K[20 TO 120F]-O-BB2-TS is an outside air temperature transmitter. A Platinum RTD, 1K-ohm @ 0°C, 385 curve reads outdoor air temperature through a vented polycarbonate shield, and the transmitter drives a 4 to 20 mA signal scaled across 20 to 120°F (-6.7 to 48.9°C). It runs on 12 to 40 VDC over a 2 wire loop (PWR, GRD) termination and BAPI rates system accuracy at ±0.065% of span.
Specifications on this page are taken from BAPI datasheet “Outside Air Units” (B50-B51), Rev. 10/05/23, and from “Outside Air (OSA) Temperature Transmitters Installation & Operation” (20920_ins_OSA_Active), rev. 05/18/26. The part number and its scaled range are taken from the current BAPI price sheet; the ordering guide in the datasheet shows a subset of available ranges and states that additional options are available.
Best For
- Outdoor-mounted outside air temperature measurement
- Sites exposed to rain, snow and large temperature swings
- High humidity outdoor sites, rated 0 to 95% RH, non-condensing at the transmitter
- Controllers that accept a 4 to 20 mA analog input
- Applications needing a scaled analog signal rather than a raw resistance input
Key Features
4 to 20 mA OutputBAPI's ordering guide defines output code T1K as 4 to 20 mA. BAPI states the adjustable outputs are set to order when the unit is built, or default to 4 to 20 mA.
Scaled RangeOutput span of 20 to 120°F (-6.7 to 48.9°C). BAPI limits span to Min. 30°F (17°C), Max. 1000°F (555°C) and zero to Min. -148°F (-100°C), Max. 900°F (482°C).
Platinum RTD Sensing ElementPlatinum RTD, 1K-ohm @ 0°C, 385 curve. Sensitivity 3.85 ohm/°C, approximate @ 32°F (0°C). Sensor accuracy 0.12% @Ref, or ±0.55°F (±0.3°C). BAPI offers high accuracy RTD matched transmitters (M option) that match the sensor to the transmitter for improved accuracy.
Loop Powered12 to 40 VDC. 2 wire loop. PWR takes 12 to 40 VDC from the controller or supply; GRD carries the 4 to 20 mA signal to the controller analog input. Two orange leads go to the internal RTD. Drives 850 ohm @ 24 VDC. Output limits < 1 mA (short), < 22.35 mA (open).
BAPI-Box 2 EnclosureNEMA 4, IP66. UV-resistant polycarbonate, UL94V-0. Two 1/2 in. NPSM plus three 1/2 in. drillable ports. 4.91 in. (124.8 mm) H x 2.82 in. (71.6 mm) W x 2.35 in. (59.7 mm) D.
Vented Shield ProbeVented polycarbonate shield, 1/2 in. (13 mm) OD. Probe length 2.1 in. (53 mm) with 1/2 in. (13 mm) NPT threads. 22 AWG stranded, Etched Teflon, plenum rated.
Technical Specifications
| Specification | Value |
|---|---|
| Product Type | Temperature transmitter |
| Output | 4 to 20 mA |
| Outputs Available | 4 to 20 mA, 0 to 5, 1 to 5, 0 to 10 or 2 to 10 VDC |
| Scaled Range | 20 to 120°F (-6.7 to 48.9°C) |
| Power Required | 12 to 40 VDC |
| Output Wiring | 2 wire loop (PWR, GRD) |
| Load | 850 ohm @ 24 VDC |
| Output Limits | < 1 mA (short), < 22.35 mA (open) |
| System Accuracy | ±0.065% of span |
| Linearity | ±(0.125 x T-20°C)/100 |
| Span Limits | Min. 30°F (17°C), Max. 1000°F (555°C) |
| Zero Limits | Min. -148°F (-100°C), Max. 900°F (482°C) |
| Transmitter Ambient | -4 to 158°F (-20 to 70°C) |
| Transmitter Humidity | 0 to 95% RH, non-condensing |
| RTD Sensor | 2 wire Platinum, 385 curve |
| RTD Element | Platinum RTD, 1K-ohm @ 0°C, 385 curve |
| RTD Sensitivity | 3.85 ohm/°C, approximate @ 32°F (0°C) |
| RTD Accuracy (Standard) | 0.12% @Ref, or ±0.55°F (±0.3°C) |
| RTD Accuracy (High) | 0.06% @Ref, or ±0.277°F (±0.15°C), [A] option |
| RTD Stability | ±0.25°F (±0.14°C) |
| RTD Self Heating | 0.4°C/mW @ 0°C |
| Probe Range | -40 to 221°F (-40 to 105°C) |
| Probe | Vented polycarbonate shield, 1/2 in. (13 mm) OD |
| Probe Length | 2.1 in. (53 mm) with 1/2 in. (13 mm) NPT threads |
| Lead Wire | 22 AWG stranded, Etched Teflon, plenum rated |
| Termination | Terminal Strip |
| Enclosure | BAPI-Box 2 (BB2) |
| Enclosure Rating | NEMA 4, IP66 |
| Enclosure Material | UV-resistant polycarbonate, UL94V-0 |
| Enclosure Entries | Two 1/2 in. NPSM plus three 1/2 in. drillable ports |
| Enclosure Dimensions | 4.91 in. (124.8 mm) H x 2.82 in. (71.6 mm) W x 2.35 in. (59.7 mm) D |
| Vented Sensor Guard | 2.10 in. (53.3 mm) |
| Enclosure Ambient | -40 to 185°F (-40 to 85°C) |
| Enclosure Humidity | 0 to 100% RH, non-condensing |
| Wall Gasket | 0.25 in. (6.35 mm) closed cell foam, impervious to mold |
| Agency | CE EN 61326-1:2013 EMC (industrial electromagnetic environment); RoHS |
| Standards | DIN 43760, IEC Pub 751-1983, JIS C1604-1989 |
Documentation
Outside Air Units Datasheet (B50-B51)Outside_Air_temp_NoPrice-v17.pdf — Rev. 10/05/23- Outside Air Temperature Transmitters Installation & Operation20920_ins_OSA_Active.pdf — rev. 05/18/26
Related Products
BAPI BA/T1K[20 TO 120F]-O-BB2 - 4 to 20 mA Outside Air Temperature TransmitterBAPI BA/T1K[-10 TO 70F]-O-BB2 - 4 to 20 mA Outside Air Temperature TransmitterBAPI BA/T1K[-20 TO 120F]-O-BB2 - 4 to 20 mA Outside Air Temperature Transmitter
Frequently Asked Questions
What is the output and scaled range?
BAPI's ordering guide defines output code T1K as 4 to 20 mA. The range code in this part number scales that output across 20 to 120°F (-6.7 to 48.9°C).
What power does the transmitter need and how is it terminated?
12 to 40 VDC. 2 wire loop. PWR takes 12 to 40 VDC from the controller or supply; GRD carries the 4 to 20 mA signal to the controller analog input. Two orange leads go to the internal RTD. It drives 850 ohm @ 24 VDC. BAPI recommends wiring the product with power disconnected. Incorrect supply voltage, polarity or connections may damage the product and will void the warranty.
Can the output be changed in the field?
This part number is a current output. The circuit board for voltage output units carries a 3-position DIP switch that sets the output value. BAPI sets it to order when the unit is built, and it may be changed in the field. That switch is on voltage output boards; BAPI states the adjustable outputs are set to order when the unit is built, or default to 4 to 20 mA.
Where should the transmitter be mounted?
Mount in the shade, away from building windows, doors or vents. A sensor in direct sunlight can read higher than actual by as much as +30%. The ideal shaded location is the north side of the building in the northern hemisphere, and the south side in the southern hemisphere. Point the shield and probe down, at least four feet above the ground or roof and a minimum of one foot below the eave.
What are the accuracy and ambient limits?
BAPI rates system accuracy at ±0.065% of span with linearity of ±(0.125 x T-20°C)/100, over a transmitter ambient of -4 to 158°F (-20 to 70°C) at 0 to 95% RH, non-condensing. The sensing RTD itself is accurate to 0.12% @Ref, or ±0.55°F (±0.3°C).
What wiring does BAPI recommend?
Twisted pair, at least 22 AWG, with sealant-filled connectors. Do not share conduit with NEC Class 1, Class 2 or Class 3 AC power wiring, or with wiring supplying highly inductive loads such as motors, contactors and relays. BAPI testing shows fluctuating and inaccurate signal levels are possible when AC power shares the conduit. All wiring must comply with the National Electric Code (NEC) and local codes. Keep the transmitter at least five feet from any radio wave-emitting device. Closer than five feet can cause unwanted interference.
5 Year Warranty — Building Automation Products, Inc. (BAPI) covers this product for 5 years. Warranty service is handled through ZOT Supply as an authorized BAPI distributor.
- Product Type:
- Temperature Transmitter
- Output Signal:
- 4 to 20 mA
- Application:
- Outside Air
- Scaled Range:
- 20 to 120°F
- Sensing Element:
- 1K Platinum RTD 385 Curve
- Power Required:
- 12 to 40 VDC
- Enclosure:
- BAPI-Box 2
- NEMA Rating:
- NEMA 4
- IP Rating:
- IP66
- Termination:
- Terminal Strip
- Warranty:
- 5 Year
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