ROTRONIC MBW 373 - Manual (Page 13)

9
Gas Inlet Connection
While the previous example did not rely on any external gas connections, the 373 is equipped
with fittings for connection of gas inlet and outlet tubing. This allows the 373 to measure the dew
or frost point of chambers and other devices that can be connected to it via tubing. If you have a
gas source you wish to measure, such as a humidity generator or chamber, connect a tube
between it and the 373 gas inlet on the back of the unit.
The input and output connectors are clearly labeled on the
Sample Gas section of the back panel. Depending on the
specific model and ordered options, the stainless steel gas
input and output connections may be 6 mm Swagelok, ¼
inch Swagelok, or ¼ inch Cajon VCR.
Note that unless your system is properly equipped to do so,
you should never attempt to measure any gas with a dew
point temperature that is at or above the temperature of the
room. If you do, condensation will form inside the tubing.
For these high dew point measurements, heated internal
components and heated hoses are required. If your 373 is
so equipped, there are electrical connections near the gas
input and output connectors for control of the hose heaters.
For further information on use of the 373 with heated hoses, see Heater Controls on page 17,
and Heating Requirements on page 29.
Range Limitations
Each 373 has a specific range of operation. To cover the entire range of -95°C frost point to
+95°C dew point requires two or more separate instruments with some limited amount of overlap
between them. While your instrument may be slightly different, the information discussed in the
section titled Determine the Measuring Range on page 26 should give some guidelines as to the
useable working range of your instrument. The specific measuring range of your instrument
should be indicated on the back panel label.