Gow-Mac 580 series, Operating Manual

Page: 37 / 68

Series 580 TCD Gas Chromatograph
September 2017, Rev. 5 37
Section 6
Valves
NOTE
)
If your instrument is not equipped with valves, go on to Section 7.
A. General
Many types of valve confi gurations are available with your Series 580 GC. The fl ow diagram of
your valve arrangement appears on the following pages. For assistance in determining the proper
valve for your application, contact GOW-MAC.
All valves must be treated with care. Foreign materials such as metal fi lings or abrasive particles
can permanently damage the sliders of the valves. GOW-MAC installs stainless steel fi lter frits on
the inlets of sampling valves to help protect against this type of damage.
The Series 580 TCD GC can be equipped with up to three (3) valves. They must be treated with
care.
CAUTION
VALVES HAVE UPPER TEMPERATURE LIMITS WHICH, IF
EXCEEDED, CAN PERMANENTLY DAMAGE SLIDERS.
UPPER TEMPERATURE LIMIT FOR VALCO VALVES IN THIS GC:
175 °C.
UPPER TEMPERATURE LIMIT FOR ACTUATORS IN THIS GC:
150 °C.
All valves may be fi tted with pneumatic actuators which are available from GOW-MAC. Air
pressure of 50 - 60 psig is required for proper operation.
B. Valves and Their Functions
Valves are used to accomplish two basic operations in GC. One is to inject a sample onto the
head of the GC column and the other, to reroute or “switch” the fl ow of the carrier gas or sample
stream.
Within the broad category of switching, there are many valve functions, such as back-fl ushing,
detector switching or column selection. (See below).
Although most valves are categorized as either sampling or switching, some valves combine both
functions and are termed “multifunction” valves.