User guide

Valves 11
Advanced User Guide 343
Valve Types
There possible valve types are:
Sampling A two- position (load and inject) valve. In load
position, an external sample stream flows through an attached
(gas sampling) or internal (liquid sampling) loop and out to
waste. In inject position, the filled sampling loop is inserted into
the carrier gas stream. When the valve switches from Load to
Inject, it starts a run if one is not already in progress. See the
example on page 346.
Switching A two- position valve with four, six, or more ports.
These are general- purpose valves used for such tasks as column
selection, column isolation, and many others. For an example of
valve control, see page 347.
Multiposition Also called a stream selection valve. It is usually
used to select one from a number of gas streams and feed it to a
sampling valve for analysis. It has a special actuator that
advances the valve one position each time it is activated, or it
may be motor driven. An example that combines a stream
selection valve with a gas sampling valve is on page 347.
Other Could be anything.
Not installed Self- explanatory.