9
User Manual HTP201 Humidity and Temperature Probe with Analogue Outputs
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For outdoor applications the HTP201 shall be equipped with a radiation shield (HA010502) which
provides protection from rain, snow and ice. This also causes a natural ventilation which largely
prevents overheating of the probe in the sun and thus a distortion of the measured values.
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Best accuracy is achieved with a velocity of min. 0.2 m/s of the air surrounding the probe. Depending
on the installation position, flow direction and flow velocity, the accuracy may decline. The following
table gives a concise overview. Please note that the vertical positioning with the sensing element
upside is the most sensitive one concerning accuracy. Because of possible self heating due to the
sensor electronics, it is crucial to have the indicated air flow velocity.
Flow direction of medium
> 0.2 m/s
> 0.2 m/s
This type of mounting
is not recommended
> 0.2 m/s
> 0.2 m/s
This type of mounting
is not recommended
> 0.2 m/s
> 0.2 m/s
Tab. 1
Mounting position, air velocity and accuracy
5 Maintenance and Service
HTP201 does not require any special maintenance, nevertheless for high accurate measurements
especially over wide RH and T ranges it is recommended to calibrate the probe every 12 months. If
needed, the enclosure or the sensing element may be cleaned as described below.
5.1 Cleaning
Use a damp soft cloth to remove deposits of dust or dirt from the exterior of the probe. Do not use any
solvents or abrasive cleaning agents.
In case of dusty, oily and polluted environment:
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Use a damp soft cloth to remove deposits of dust or dirt from the exterior of the probe. Do not use
any solvents or abrasive cleaning agents.
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The filter cap shall be replaced once in a while with an E+E original one (see below).
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If needed, the sensing element of the humidity probe can be cleaned by the user (see cleaning
www.epluse.com/cleaning-instructions
5.2 Filter Cap Replacement
In a dusty or polluted environment it might be necessary to replace the filter cap once in a while. In most
of the cases, a clogged filter shows visible contamination or dirt. Longer response time of the humidity
measurement also indicates a clogged filter cap. In such cases, replace the filter by a new, original one,
Procedure
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Turn the filter cap counter-clockwise for removing it.
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Install the new filter cap finger tight by turning it clockwise.
While replacing the filter cap take very good care to not touch or rub the sensing element.
