Vaisala DM500 - Manual (Page 40)

User's Guide ______________________________________________________________________
38 __________________________________________________________________ M210205EN-D
6 mm fitting with the ¼" adapter fitting (provided), if needed. If
you use the adapter fitting, see that the 6 mm side is connected
to the Gas In -connection.
2. Attach the gas tubes (diameter of 6 mm or ¼") to the Swagelok
fittings.
3. Replace the Swagelok fitting (with the tubing) into the GI
connector (connect the Gas Out tubing similarly, if necessary).
NOTE
When measuring high dewpoint temperatures with heated lines, the
connection fitting shall be insulated carefully to prevent
condensation.
4. Let the sample gas flow with a flow rate of 0.5...1.5 slpm
(recommended 1.0 slpm)
5. If needed, adjust the sample flow rate by turning the Allen screw
(in the sensor cup, see Figure 2 on page 16, item 2) with a key
(provided).
WARNING
Do not connect flammable, highly reactive or toxic gases to the
instrument. Ensure adequate ventilation when using other gases than
air.
Selecting the Cooling Method
Use either air or water in sensor cooling.
- water cooling: generally required when measuring dewpoint below
-50 ºC (-58 ºF) and recommended when measuring dewpoints
higher than +40 ºC (+104 ºF)
Use of subzero water/glycol or ethanol mixture, as the cooler liquid is
not recommended, as there is a risk of substantial ice formation inside
the sensing unit. However, subzero cooling liquid can be used for
short periods. To ensure sufficient cooling capacity, please follow the
instructions below. The temperature of the cooling air/water and flow
rate of the sample gas has an effect on the cooling capacity.
When using air cooling, the fan inside the device is cooling the
system. When using water cooling, connect the water as instructed in
the following chapter.