Calibration And Adjustment; Field Check Using Dm70 - Vaisala DRYCAP DMT152 User Manual

DMT152 User Guide
• When installing the transmitter after a filter change, always use a new sealing ring (ISO
and UNF threads only).
Replace the filter as follows:
1. Grip the old filter from the top of the filter body using an 11 mm socket wrench. Turn the
filter counterclockwise until it is loose.
2. Pull the filter straight out carefully; do not damage the sensor, and do not lose the spring
washer.
3. Take the new filter, and insert it to the filter threads. The spring washer should be under
the filter.
4. Tighten the new filter by turning it clockwise with the 11 mm socket wrench. Tighten to
5 Nm.
6.3 Calibration and Adjustment
DMT152 is fully calibrated as shipped from the factory. The recommended calibration interval is
2 years. If the transmitter is used in the wet end of the measurement range, calibration should
be done every year. Calibration should also be done if there is a reason to believe that the
device is not within its accuracy specifications.
You can perform a simple field checking operation by comparing the readings of DMT152 and
DM70 handheld dewpoint meter with a calibrated reference probe. For more information, see
Field Check Using DM70 (page
If there is need for calibration or adjustment, contact a Vaisala Service Center or your local
Vaisala representative.
6.3.1 Field Check Using DM70
To check the accuracy of DMT152 in the field, you need the following equipment:
• A fully charged MI70 indicator (the measurement display that is included in the
DM70 package).
• A calibrated reference probe that is suitable for the intended measurement
environment and dew point range. You can use a DMP74 probe from the DM70
for dew point down to −60 °C (−76 °F), or a second DMT152 for full
measurement range.
• A connection cable between the DMT152 and the MI70 indicator (Vaisala order
code 219980).
• A reference environment with a stable dew point and temperature in a suitable
range for both probes. The normal measurement environment of the
transmitter can also be used, if it meets these criteria.
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