Heath Consultants EI-5 Ethane Gas Identifier - Manual (Page 6)

EI-5 Manual Rev A 3
the equilibrium condition in clean air. Any substance foreign to clean air
disturbs this balance, changing the ion flow in the conductance band of
the semi-conductor detects the low concentration and early presence of
foreign gases (methane, ethane, propane) rather than giving a quantita-
tive measure of their concentration. As the various components or hydro-
carbons elute through the separation column they react on the semi-con-
ductor and the resulting change in electrical resistance is amplified and
presented visually on the instrument display.
Flow System: The flow system is so arranged that the Ethane Identifier
cannot be used as a leak locator. It is set up as a field type gas chromato-
graph to differentiate between gases by means of a multi-port selector
valve, short sample loop and separation column.
Valve “Sample” Position: With the selector valve set to “Sample” the
sample is drawn into the instrument and fills the short sample loop. Excess
sample passes through the sample system and exits through the port on
the end of the instrument. The sample does not pass over the sensor in
this position so no meter readings occur.
Valve “Time” Position: After a gas sample has been drawn into the in-
strument, the combustible gas is present in the short sample loop. Switch-
ing the valve to the “Time” position causes the internal pump to push the
sample through the separation column (Chromatograph), over the sensor,
and then exhausts it to the outside of the instrument case at the vent port
located at the bottom of the instrument.