Siemens Maxum II PD PA AP Service Manual page 32

Valves
4.2 Liquid Injection Valve
Functional Description
The SLIV uses a moving injection tappet attached to a
piston actuator. Sample is injected via a groove or cross
hole in the tappet. In the filling position, the sample flows
continuously through the cross hole or the ring groove
of the injection tappet. When injecting, the tappet is
pushed pneumatically into the heated vaporization area.
The liquid in the cross hole or ring groove is vaporized
and flushed by the carrier gas into the column. The tap‐
pet is then shifted pneumatically, via the piston actuator,
back into its original position. Sample then passes
through the injection hole again.
The Sample flow unit and control cylinder are located
outside the chromatograph oven. The vaporizer is loca‐
ted in the chromatograph oven. A heater assemble con‐
trols the temperature of the vaporizer. The vaporizer
temperature can be raised to vaporize high boiling point
samples.
Samples that contain salts that would cake on a dia‐
phragm valve during injection are washed off when the
valve stem is moved back to the flowing sample. Sam‐
ples that contain a lot of solids, which would clog a dia‐
phragm valve, can be measured using a Siemens Liquid
Injection Valve. With the use of a temperature control
circuit, the vaporizer temperature can be changed for
different boiling point samples to insure complete vapor‐
ization.
32
Sample Injection
Maxum II Valves and Oven Components
Service Manual, 10/2018, A5E42019844001