ROTRONIC MBW 373 - Manual (Page 29)

25
Gas Input and Output
The gas input and output fittings are used for connection of the 373 to the sample gas. Based
on the original configuration of your system, it will generally contain ¼” or 6 mm Swagelok
®
tube
fittings, or ¼” Swagelok
®
VCR
®
metal gasket face seal fittings.
While a connection to the gas input is most likely required, the gas output connection is often left
unconnected. If the fittings are capped, you’ll need to remove those caps for operation or
connection of sample lines.
Hose Heaters
If your system is equipped with controls for external heated hoses, you’ll see electrical
connectors next to the gas input and output fittings. The connectors mate with those on the
heated hose.
Control of the both the input and output heated hoses is based on temperature measurement of
the input hose only. Therefore, if a heated hose is connected to the gas output, you must also
connect a heated hose to the gas input in order to allow the system to control the hose
temperature. For control of the heated hoses, see Heater Controls on page 17.
Barometric Pressure Input
Some systems are equipped with a relative pressure sensor for measurement of the head
pressure. On those systems, it is also necessary to accurately measure the barometric pressure
so that the absolute pressure of the head may be determined. Systems with a barometric
pressure sensor have the pneumatic fitting of that sensor brought to the back panel. This fitting
must remain open for operation.
Cooling Water
If your system is so equipped, there are fittings (generally ¼” or 6 mm brass Swagelok
®
) on the
back panel for connection of auxiliary cooling water. When using these fittings, please note that
the water is controlled (on/off) by a solenoid valve which operates at a selectable dew point
temperature. It must be allowable for the cooling water to be shut off by the 373’s internal
solenoid valve. Therefore, cooling water should never be connected in series among multiple
systems. Rather, connection of cooling water to multiple systems should be in parallel. To
enable use of cooling water and set the temperature at which it turns on, see Water Cooling on
page 18.