ROTRONIC HP22A - Manual (Page 11)

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
© 2010-2012; Rotronic AG E-M-HP22-V2_13
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.