User guide

E-M-HP22-V2_13

Rotronic AG

Bassersdorf, Switzerland

Document code Unit

HygroPalm HP22-A hand-held indicator:

User Guide

Instruction Manual

Document Type

Page

11 of 16

Document title

o SensorTest: Off means that the humidity sensor has not been tested due to the configuration settings of

the test. For a description of the automatic humidity sensor test and drift compensation (SQ-tuning) see

documents E-T-AC3000-DF-V1 and E-M-HW4v3-F2-006

4.10 Practical advice for measuring humidity

The most common source of error when measuring relative humidity is a difference between the

temperature of the probe and the temperature of the environment. At a humidity condition of 50 %RH, a

temperature difference of 1°C (1.8 °F) typically results in an error of 3 %RH on relative humidity.

When using the HP22 hand-held indicator, it is good practice to monitor the display for temperature

stability. The probe should be given sufficient time to equilibrate with the environment to be measured. The

larger the initial temperature difference between the probe and the environment to be measured, the more

time temperature equilibration requires. This time can be shortened, and errors avoided, by using the probe

configuration that fits best for your application.

In extreme situations, condensation may occur on the sensors when the probe is colder than the

environment. As long as the humidity / temperature limits of the humidity sensor are not exceeded,

condensation does not alter the calibration of the sensor. However, the sensor has to dry out before it can

provide a valid measurement.

Non-moving air is an excellent insulator. When there is no air movement, surprising differences in temperature

and humidity can noted over short distances. Air movement at the probe generally results in measurements

that are both faster and more accurate.

5 Maintenance

5.1 Replacing the battery

To replace the battery, turn the latching button counter-clockwise and pull out the battery holder.

5.2 Service cable

• Cable AC3006 converts UART (service connector) to USB and is used to connect the HP22 to a USB port

of a PC running the ROTRONIC HW4 software. Prior to using this cable, the ROTRONIC USB driver must

be installed on the PC. Both the driver and the installation instructions (document E-M-HW4v3-Main) are

located on the HW4 CD.