Tuning the Backflush Time 3
Natural Gas Analyzers 26
Tuning the Backflush Time on a HayeSep A
For each new HayeSep A channel, with a backflush option, it is
necessary to tune the backflush time properly. The tuning
procedure of the HayeSep A channel is different than the tuning
procedure of a CP-Molsieve 5A, PoraPLOT U, or 4 meter CP-Sil 5
CB channel.
This section describes how to tune the backflush time for the
HayeSep A channel. The goal for tuning the HayeSep A channel
is get all peaks of interest, components up to propane, on the
HayeSep A column while all unwanted peaks that elute after
propane are backflushed.
Tuning procedure for HayeSep A channel
1 Set the backflush time of the HayeSep A channel to 0 seconds.
2 Set an appropriate run time for the first analysis (for
example 300 seconds or longer).
3 Analyze the NGA Gas Calibration standard and identify all
components in the calibration standard.
4 When all peaks of interest are identified, select a proper
backflush time after propane peak.
Figure 27 shows an example of the tuning procedure of
HayeSep A channel. In this example the propane peak elutes
around 90 seconds, proper backflush time for the HayeSep A
here is around 120 seconds.
Consider that the total run time must be sufficient to backflush
all unwanted components from the column. The ideal total run
time is approximately twice the backflush time or higher. So in
this example, a total run time of 240 seconds is sufficient to
backflush all unwanted components from the HayeSep A channel.
Figure 27 Selecting backflush time for a HayeSep A channel
Seconds
10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170
mVolt
20
40
60
80
100
Carbon Dioxide
Ethane
Propane
i--Butane
Nitrogen
Methane
Peaks of Interest
Appropriate
Backflush Time
Unwanted Peak
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