User's Guide _______________________________________________________________________
CHAPTER 4
MAINTENANCE
This chapter provides information that is needed in basic maintenance of
HMDW80 series.
Cleaning
NOTE
The body of the transmitter can be cleaned by wiping with a moistened lint-free cloth. Do not use cleaning agents or solvents, or blow pressurized air into the transmitter housing or on the filter.
Do not attempt to clean contaminated INTERCAP ® sensors or filters.
Instead, replace them with new parts. Filters and sensors can be
purchased from Vaisala. For order codes, see section Spare Parts and
Accessories on page 46.
Calibration
You can verify the performance of your HMDW80 series transmitter by comparing its reading with the reading from a portable reference instrument such as the HM70 Hand-Held Humidity and Temperature
Meter. For operating instructions, refer to the documentation of your reference instrument.
If the comparison indicates that the reading from the transmitter is not within specification, the transmitter may need to have its filter and sensor replaced.
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Chapter 4 _______________________________________________________________ Maintenance
Replacing the INTERCAP
®
Humidity Sensor
HMDW80 series transmitters use the Vaisala INTERCAP ® humidity measurement. The INTERCAP ®
sensor for
sensor is designed to be replaced when necessary, and does not require adjustment by the user.
Replacing the INTERCAP
®
Sensor on
Models HMD82/83 and HMW88/89
REQUIRED
TOOLS
- New INTERCAP ® humidity sensor.
- New filter (always recommended when replacing the sensor).
- Duct models only: medium size crosshead screwdriver (Pozidriv).
1. Power down the transmitter.
2. Duct models only: loosen the tightening screw on the fastening flange, and pull the probe out of the duct.
3.
Remove the filter to access the sensors. See Figure 20 below.
4. Pull out the old INTERCAP ® sensor, and insert the new one.
5. Insert the new filter.
6. Duct models only: push the probe back into the duct, to the same depth where it was before. Tighten the tightening screw on the fastening flange.
7. Power up the transmitter.
8. Verify that the transmitter now provides a valid humidity reading.
1
2
3
4
1305-024
Figure 20 Sensors on HMD82/83 and HMW88/89 Models
1 = Vaisala INTERCAP® sensor. Handle by the plastic frame.
2 = Temperature sensor. Do not touch or attempt to remove.
3 = Sensor socket.
4 = Transmitter probe.
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User's Guide _______________________________________________________________________
REQUIRED
TOOLS
Replacing the INTERCAP
®
Wall Models HMW82/83
Sensor on
- New INTERCAP ® humidity sensor.
- Small flat head screwdriver.
1. Use the screwdriver to push down on the tab on the top of the transmitter and open the transmitter cover.
2.
Remove the old sensor, and insert the new one. See Figure 21 below.
3. Reconnect the cover to the mounting base.
4. Verify that the transmitter now provides a valid humidity reading.
1
1305-018
Figure 21 INTERCAP ® Sensor on HMW82/83 Models
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Chapter 4 _______________________________________________________________ Maintenance
REQUIRED
TOOLS
NOTE
Replacing the INTERCAP
®
Outdoor Models HMS82/83
Sensor on
- New INTERCAP ® humidity sensor.
- New filter (always recommended when replacing the sensor).
- Medium size crosshead screwdriver (Pozidriv)
- Flat head screwdriver
- 3 mm hex key (Allen key) for opening the radiation shield screws.
- If transmitter mounted on pole: 2.5 mm hex key for opening and tightening the set screw.
You will need to remove the radiation shield to access the sensor, and this is difficult to do while the transmitter remains mounted on a pole or wall. The procedure below takes advantage of the detachable screw terminal to allow the cable to remain in place during the operation.
1. Power down the transmitter.
2. Open the transmitter cover and unplug the screw terminal. This allows you to leave the cable and cover at the installation site.
1305-019
Figure 22 Unplugging the Screw Terminal
3. Remove the transmitter from its installation point.
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User's Guide _______________________________________________________________________
4. Open the two long screws that hold the radiation shield, and pull them out.
1305-020
Figure 23 Opening the Radiation Shield Screws
1305-021
Figure 24 Removing the Radiation Shield Screws
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Chapter 4 _______________________________________________________________ Maintenance
5. Use a flat head screwdriver to push on the visible plastic tab below the radiation shield.
Figure 25 Location of Locking Tab
1305-022
6. Tilt the radiation shield away from the opened tab. This opens the second tab on the other side, allowing you to remove the radiation shield.
1305-023
Figure 26 Removing the Radiation Shield
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User's Guide _______________________________________________________________________
7. Open the filter to expose the sensors.
1305-017
Figure 27 Filter Removed
8. Pull out the old INTERCAP ® sensor, and insert the new one.
1
2
3
4
1305-024
Figure 28 Sensors on HMS82/83 Models
1 = Vaisala INTERCAP® humidity sensor.
Handle by the plastic frame.
2 = Temperature sensor. Do not touch or attempt to remove.
3 = Sensor socket.
4 = Transmitter probe.
9. Insert the new filter.
10. Reassemble, remount, and reconnect the transmitter.
11. Power up the transmitter.
12. Verify that the transmitter now provides a valid humidity reading.
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