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

EI-5 Manual Rev A 2
When the presence of a combustible gas or vapor has been established
with a C.G.I., use the Ethane Identifier with the internal pump to draw a
sample into the instrument. The valve should be in the “Sample” position.
No display indication will occur as the sample is being drawn into the in-
strument. As the sample is drawn into the instrument, a portion of the sam-
ple is trapped inside the instrument in the short sample loop. Switching the
valve to “Time” position sends this trapped sample through the separation
column where the various components in the sample are separated by
their molecular size. The internal pump is used to push the sample through
the instrument.
If more than one type of combustible component is present in the sample
the lightest one (smallest molecule) will be released first followed by the
next heavier (larger molecule).
These components pass over the sensor in the instrument and are ob-
served visually on a display. If a record of the chromatographic analy-
sis is required the data logger records the date and time and a value at
one second intervals. Normally, a full-scale graphical peak will occur for
each component but not always, particularly, when low concentrations are
being analyzed. The instrument can provide reliable results with sample
concentrations measured on a C.G.I. of 800 ppm to 100 LEL natural gas.
However, for optimum results attempt to analyze samples in a concentra-
tion of about 10 LEL to 75 LEL. To again emphasize the design of the
instrument, there is no indication on the display when the valve switch is in
the “Sample” position. It is mandatory to use a C.G.I. to determine sample
concentration before using the Ethane Identifier. Zeroing the meter exactly
at “O” is not critical as the graph may drift during the test. This normally
presents little problem to the end result.
Electronic Principle: The electrical schematic is based on the semi-con-
ductor type sensor (metallic oxide bead). The Hetek Ethane Identifier uses
a semi-conductor type sensor that is pre-determined to be ultra sensitive
to the light hydrocarbons. The tough bead of metallic oxide, semi-con-
ductor material, coats itself with oxygen molecules, which is considered
PRINCIPLE OF OPERATION