Rotronic HygroPalm HP21

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Rotronic HygroPalm HP21

The HP21 is the ideal instrument for humidity and temperature measurements in simple applications. The integrated HC2 probe guarantees measuring results of the highest accuracy.


The HP21 is a highly accurate handheld indicator that displays relative humidity, temperature and dew or frost point temperature. The HP21 is perfect for spot checking HVAC installations, manufacturing or storage areas and any ambient air measurement within the temperature range of -10 to 60°C (14 to 140 °F). The HP21 is designed to meet a wide range of user requirements from the most basic applications to the most demanding applications.

The HP21 indicator offers an extensive set of settings and functions that can be configured and enabled by the user with the ROTRONIC HW4 software. In spite of its high end design, the HP21 is ideal even as a simple humidity and temperature indicator.

Mobile inspection and random tests in HVAC, the pharmaceutical industry and building management systems


  • Range of application -10…60 °C / 0…100 %rh
  • Accuracy at 23°C ±5 K: 1 %rh, 0.2 K
  • Adjusted at 23 °C and 10, 35, 80 %rh
  • Service interface (UART)
  • Calculation of dew and frost point


Dimensions 268 x 72 x 30 mm
Operating range -10…60 °C / 0…100 %rh
Accuracy at 23 ±5 °C ±1.0 %rh / ±0.2 K
Accuracy w. adjustment profile “standard” at 23 °C / 10, 35, 80 %rh ± 1.0 %rh / ± 0.2 K
Measuring range with integrated probe -10…60 °C / 0…100 %rh
Power supply / Power consumption 9 V battery, power supply
4 mA consumption without lighting
Long-term stability <1 %rh / year
Humidity sensor Hygromer IN-1
Temperature sensor PT100 1/3 DIN Class B
Probe protection Polycarbonate plastic cage, black
Response time t 63 <3 sec.
Allowed wind speed 40 m/s, with filter
Psychrometric calculations Dew or frost point
Calibration / adjustment with keypad
Reproducibility Airchip <0.02 %rh / 0.01 K
Initialisation time Typically
Measurement interval 2 seconds
Display type Graphic display. Display freely configurable.
Backlight with Backlight
Alarm indicators Yes
Battery indicator Low Batt. Display
Exploitation software ROTRONIC HW4
Menu guidance Yes
Trend indicator Yes
Probe adjustment by software Yes, with service cable
Firmware update With internet and HW4 software
User information from Software HW4 (devicemanager)
Data processing via HW4 Graphics, statistics, analysis, qualification, etc.
Device Protection by password Yes
Service Interface Mini USB (UART)
Max. cable length Up to 5 m with passive cable. Up to 100 m with active cable.
Enclosure material ABS
IP protection rating IP40
Fire protection class Complies UL94-HB
FDA/GAMP compatibility FDA 21 CFR Part 11 and GAMP compatible


Datasheet (PDF)


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