| Temperature Sensor |
| Operation range Internal sensors |
-40° to 70°C (-40° to 158°F) |
| External temperature sensor |
-40° to 70°C (-40° to 158°F) |
| External sensors |
-40° to 100°C (-40° to 212°F), with tip and cable immersion in fresh water up to 50°C (122°F) for one year |
| Accuracy |
±0.21°C from 0° to 50°C (±0.38°F from 32° to 122°F) |
| Resolution |
0.02°C at 25°C (0.04°F at 77°F) |
| Response time (typical to 90%) |
| U23-002A External temperature sensor |
5 minutes in air moving 1 m/sec |
| Stability (drift) |
< 0.1°C (0.18°F) per year |
| Relative Humidity Sensor |
| Operation range |
0-100% RH, -40° to 70°C (-40° to 158°F) Exposure to conditions below -20°C (-4°F) or above 95%
RH may temporarily increase the maximum RH sensor error by an additional 1% |
| Accuracy |
±2.5% from 10% to 90% RH (typical), to a maximum of ±3.5% including hysteresis. See Plot B for full range |
| Resolution |
0.03% |
| Response time (typical to 90%) |
| U23-002A |
5 minutes in air moving 1 m/sec with protective cap |
| Stability (drift) |
< 1% per year typical |
| Logger |
| Operation range |
-40° to 70°C (-40° to 158°F) |
| Real-time clock |
± 1 minute per month 0° to 50°C (32° to 122°F) |
| Battery |
1/2 AA, 3.6 Volt lithium, user-replaceable (part # HP-B) |
| Battery life (typical use) |
3 years with 1 minute or greater logging interval |
| Memory (non-volatile) |
64K bytes memory (approx. 21,000 temperature and RH measurements) |
| Materials All models |
ASA styrene polymer housing and mounting clamp; polypropylene protective cap; Buna-N o-ring(s) U23-001, U23-002 only: ASA styrene polymer RH sensor cap; modified hydrophobic polyethersulfone membrane |
| Cables |
| U23-002A |
One 184 cm (6 ft.) PVC cable; sensor diameter 1 cm (0.38 in.) |
| Environmental rating |
Electronics housing is NEMA 6P equivalent (tolerant of brief submergence)
Units with RH sensors are NEMA 4 equivalent (splash-resistant) |
| Launch modes |
Immediate start; delayed start |
| Logging interval |
Fixed-rate or multiple logging intervals, with up to 8 user-defined logging intervals and durations; logging intervals from 1 second to 18 hours (refer to HOBOware software manual) |
| Offload modes |
Offload while logging; stop and offload |
| Battery indication |
Battery voltage can be viewed in status screen and optionally logged in datafile. Low battery indication in datafile |
| Weight |
118 g (3.1 oz) |
| Dimensions |
Housing measures 10.2 × 3.8 cm (4.0 × 1.5 in.) |
| NIST certificate Temperature certificate available for additional charge |
| The CE Marking identifies this product as complying with the relevant directives in the European Union (EU) |