Changing the filter - DMT152

DMT152 User Guide

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User guide

If the filter is contaminated, it should be replaced. New filters can be ordered from Vaisala (order code 220957). Be careful when changing the filter, since it is easy to break the sensor when the filter is removed.


If the transmitter is installed in a pressurized chamber, always make sure that the pressure of the chamber is equalized with the ambient pressure prior to removing the transmitter. When the transmitter is removed for maintenance, cap the hole with a capped nut. This way, the process can be running although the transmitter is not in place.

Plugs are available from Vaisala for ISO threaded connections (Vaisala order code 218773) and NPT threaded connections (Vaisala order code 222507).

Figure 1. Filter structure
Vaisala DRYCAP sensor
Spring washer
Stainless steel mesh filter (do not touch)
Top of the filter

When replacing the filter, note the following:

  • The pores of the steel mesh may become blocked if touched. Do not touch the filtering surface with your hands or any tools. Always handle the filter from the top of the filter body.
  • Touching the filter with your fingers will also deposit oil and dirt on the filter, which may affect the measurement. Always handle the filter with gloved hands.
  • 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.