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HMP80 Series User Guide
3.3 Condensation prevention functions
Condensation prevention prevents water from condensing on the sensor and interfering with
humidity measurement. Use of condensation prevention is controlled by a single setting that
can be changed with the Insight software or the Indigo80 handheld indicator.
By default, condensation prevention is off.
When condensation prevention is enabled, the probe will automatically use its available
condensation prevention functions. When warming is active, values of output parameters that
depend on temperature measurement (for example, relative humidity) are unavailable, unless
the temperature compensation setting is set to read the temperature from an external source.
Output parameters that can be measured or calculated without this external temperature
information, such as dew point temperature, are available even without the temperature input.
Sensor warming
The sensor warming feature of the condensation prevention function is intended for improving
the condensation tolerance of HMP80 probes. It warms the humidity sensor when necessary to
keep its temperature above the dew point of the measurement environment. When sensor
warming is activated, all temperature-dependent output parameters become unavailable,
unless the temperature compensation setting is set to read the temperature from an external
source. The output parameters become available again 4 minutes after the warming is
stopped.
Sensor warming is intended for improving the condensation tolerance of the
probe in measurement environments that may occasionally cause condensation
to form. It is not intended for environments where continuous warming is needed.
3.4 Environmental compensation
Environmental compensations improve the measurement accuracy of the probe. You can
configure the settings with the Insight software or the Indigo80 handheld indicator.
Pressure compensation
The pressure of the measured environment affects the accuracy of humidity calculations,
especially calculations that are dependent on pressure (for example, mixing ratio). To achieve
accurate output of all humidity parameters, you are recommended to update the value of the
pressure compensation setpoint to match the environmental pressure when installing the
probe.
For example, when you install the probe in a process with a pressure differing from normal
atmospheric pressure, update the correct pressure into the pressure compensation setpoint
parameter or register of the probe using the Insight software or the Indigo80 handheld
indicator.
The entered value is persistent and remains unchanged at device restart.
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