Temperature Sensor
Operation range internal sensors: -40° to 70°C (-40° to 158°F)
U23-002 external temperature sensor: -40° to 70°C (-40° to 158°F)
U23-003 and U23-004 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); see Plot A
Resolution: 0.02°C at 25°C (0.04°F at 77°F); see Plot A
Response Time (typical to 90%)
U23-001 internal sensor: 40 minutes in air moving 1 m/sec
U23-002 external temperature sensor: 5 minutes in air moving 1 m/sec
U23-003 and U23-004 external sensors: 3 minutes in air moving 1 m/sec; 30 seconds in stirred water
Stability (drift): < 0.1°C (0.18°F) per year
Relative humidity sensor (U23-001, U23-002 only): 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 Ttime (typical to 90%)
U23-001: 40 minute in air moving 1 m/sec with protective cap
U23-002: 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)