Chapter:
INJECTORS
&
GAS VALVES
Topic:
Dual Loop Injection ofTwo Separate Streams Onto One Column
10 Port
Gas
Sampling Valve in LOAD Position
10 Port Gas Sampling Valve in INJECT Position
This
gas
sampling valve configuration permits two separate
loops to
be
loaded simultaneously from two streams and
injected together onto the analytical column.
Sample
loop
2
out
Sample loop2
internal
standard
To
cohaon
"---.......- Sample
loop
2
in
Fig. I
Sample loop 1
sample
stream
Sample
loop
I
in__
oJ
Sample
loop
1 "'" - .......
-+<
The following is a
description of the 10 port gas
sampling valve plumbed to
permit the loading ofdual
loops from separate streams
for injection asa single
sample onto a single
analytical column.
In the LOAD position:
Two separate loopcircuits
exist
in
this
configuration.
Sample loop#1receives
sample through port #1, and
vents through port
#2.
Sample loop
#2
receives
sample through port #8 and
vents through port #7.
Meanwhile the carriergas is
routed into port #4 from the
injector, through the valve,
and out through port
#5
to
the analytical column and
detector.
'This
configuration is convenient forapplications where an
internal standard must
be
inserted into the sample prior to
analysis.
Both
samples are then merged and deposited
on-column for analysis when the sampling valve
is
rotated
to
the INJECT position.
Carrier
gas
in
-~--::X:::-=::.{~-
In the INJECT position:
When the valve is rotated
to
the INJECT position, both
sample loop inlets and outlets
are isolated (ports #1 and
#2,
and #7 and #8). The carrier
gas entering the valve at
port
#4 is diverted into loop #1
through port
#3.
Loop #1 is
now
in
series with loop
#2
and the contents of both
loops is swept outby the
carrier gas flow,
to
exit
through port
#5
to the
analytical column for
analysis. Atno time is the
carrier gas
flow
to
the
column interrupted,
protecting both the column
and the detector.
Sample loop 1
out
- .......
-+{
Sample
loop
1
in
Sample
loop
I
sample
stream
Fig. 2
To
column
')-1_-
Sample loop2 out
'-~-
Sample loop2
in
Sample loop2
inlenW.....wd
