The HMP155A, manufactured by Vaisala, monitors relative humidity (RH) for the range of 0 to 100% RH and temperature for the range of -80° to +60°C. It can provide reliable measurements for a wide range of applications, as part of a weather station system or as a single instrument. All Campbell Scientific dataloggers are compatible.Read More
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 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.
|Electromagnetic Compatibility||Complies with EMC standard EN61326-1 Electromagnetic|
|Filter Description||Sintered PTFE|
|Housing Body Material||PC|
|Voltage Output||0 to 1 Vdc|
|Average Current Consumption||≤ 3 mA (analog output mode)|
|Operating Voltage||7 to 28 Vdc|
|Settling Time||2 s (at power up)|
|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.)|
|Sensing Element||HUMICAP 180R|
|Measurement Range||0 to 100% RH (non-condensing)|
|Factory Calibration Uncertainty||
|Sensing Element||PT 100 RTD 1/3 class B IEC 751|
|Measurement Range||-80° to +60°C|
|Entire Temperature Range||Refer to graph in probe manual.|
Please note: The following shows notable compatibility information. It is not a comprehensive list of all compatible products.
When exposed to sunlight, the HMP155A must be housed in a 41005-5 or RAD14 14-plate naturally aspirated radiation shield. The 41005-5 and RAD14 attach to a crossarm, mast, or user-supplied pipe with a 2.5 to 5.3 cm (1.0 to 2.1 in.) outer diameter. The RAD14 uses a double-louvered design that offers improved sensor protection from driving rain, snow, and insect intrusion, It also has lower self-heating in bright sunlight combined with higher temperatures (> 24°C [~75°F])
and low wind speeds (< 2 m s-1 [~4.5 mph]), giving a better measurement.
Description: Example CR1000X programs that measure either the analog voltage or RS-485 output of the HMP155A. The analog voltage programs use either the VoltSE or VoltDiff instruction and switch power to the sensor only during measurements. One program also calculates the mean vapor pressure. The RS-485 program measures the RS-485 output with an SDM-SIO1A/SIO4A. Although these programs are written for the CR1000X, programs for other dataloggers will be similar.