Campbell Scientific HMP155A-L User Manual

PRODUCT

The HMP155A provides reliable relative humidity (RH) and
temperature measurements for a wide range of applications.

It uses a HUMICAP®180R capacitive thin film polymer sensor
to measure RH over the 0 to 100% RH range. A PRT measures
temperature over the -80° to +60°C range. This rugged,
accurate temperature/RH probe is manufactured by Vaisala.

Well-suited for long-term, unattended applications
Accurate and rugged

The HMP155A uses a HUMICAP180R capacitive thin film
polymer sensor to measure RH, and a PRT to measure
temperature.

To reduce the current drain, power can be supplied to the
HMP155A only during measurement when the sensor is

Electromagnetic
Compatibility

Complies with EMC standard

EN61326-1 Electromagnetic
Filter Description Sintered PTFE
Housing Body Material PC
Housing Classification IP66

Temperature and Relative Humidity Probe

HMP155A-L

Accurate, Wide
Temp Range

Higher-end sensor where higher
accuracy is required

Overview

Benefits and Features

Detailed Description

Manufacturer's note: In changing temperature conditions
with high humidity, the probe temperature can lag behind
the temperature of surrounding air and this can cause risk of
condensation on the sensor. A wet probe cannot observe
the actual humidity in the ambient air. If the condense water
is contaminated, the life span of the probe may shorten and
the calibration may change.

Mounts to a mast, crossarm, or user-supplied pole
Compatible with most Campbell Scientific data loggers

connected to the datalogger’s switched 12 V terminal.
Dataloggers that do not have a switched 12 V terminal, such
as the CR510 or CR7, can use the SW12V switched 12 V
device to switch power to the sensor only during
measurement.

Specifications

Voltage Output 0 to 1 Vdc
Average Current

Consumption
Operating Voltage 7 to 28 Vdc
Settling Time 2 s (at power up)

For comprehensive details, visit: www.campbellsci.com.au/hmp155a

≤ 3 mA (analog output mode)

Field-Replaceable Chip or
Recalibrate

Recalibrate

Tip Diameter 1.2 cm (0.5 in.)
Length 27.9 cm (11 in.)
Head Height 4 cm (1.6 in.)
Body Height 2.4 cm (0.9 in.)
Body Width 2.0 cm (0.8 in.)

Relative Humidity

Sensing Element HUMICAP 180R
Measurement Range 0 to 100% RH (non-condensing)
Response Time 60 s (90% step change)

20 s (63% step change)
The response time for the RH
specification is for the
HUMICAP 180R at 20°C in still
air with sintered PTFE filter and
a 0 to 75% RH step change.

Factory Calibration
Uncertainty

The factory calibration
uncertainty is defined as ±2
standard deviation limits.
Uncertainty is at +20°C. Small
variations are possible; see
also the calibration certificate.
±1.0% RH 40 to 97% RH

±0.6% RH 0 to 40% RH

Accuracy ± (1.2 + 0.012 × reading) % RH

(at 40° to 60°C)
±1% RH (at 15° to 25°C, 0 to
90% RH)

-NOTE- Accuracy
specifications include non­linearity, hysteresis, and
repeatability.

±1.7% RH (at 15° to 25°C, 90 to
100% RH)
±(1.0 + 0.008 × reading) % RH
(at -20° to +40°C)
±(1.2 + 0.012 × reading) % RH
(at -40° to -20°C)
±(1.4 + 0.032 × reading) % RH
(at -60° to -40°C)

Air Temperature

Sensing Element PT 100 RTD 1/3 class B IEC 751
Measurement Range -80° to +60°C
Accuracy ±(0.226 - 0.0028 x

temperature)°C (-80° to +20°C)
±(0.055 + 0.0057 x
temperature)°C (+20° to
+60°C)

Entire Temperature Range Refer to graph in probe manual.

For comprehensive details, visit: www.campbellsci.com.au/hmp155a

© 2021 Campbell Scientific, Inc. | 01/13/2021