Gow-Mac 400 Series, Руководство по эксплуатации

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35 Series 400 / 402 Gas Chromatograph Operating Manual GOW-MAC Instrument Co.
May 2017, Rev. 7
Chapter 6 - Valves
6.1 Valves
If your GC is not equipped with Gas Sample Valves, proceed to the next chapter.
A. 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
recommends 2-micron particle fi ltration of gases connected to the gas sample valves.
WARNING
!
VALVES HAVE UPPER TEMPERATURE LIMITS WHICH,
IF EXCEEDED, CAN PERMANENTLY DAMAGE SLIDERS.
GOW-MAC USES VALCO VALVES IN ALL OUR GCs. THESE
VALVES USE SLIDERS OF FILLED TEFLON
®
AND HAVE
AN UPPER TEMPERATURE OF 175 °C OR 300 °C. DO NOT
EXCEED THESE TEMPERATURES.
UPPER TEMPERATURE LIMITS:
VALCO LOW TEMPERATURE VALVES: 175° C
VALCO HIGH TEMPERATURE VALVES: 300 °C
6.2 Valves and Their Functions
Valves are used to accomplish two basic operations in gas chromatography. One is 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 or switching there are many valve functions, i.e., back-fl ushing,
detector switching or column selection.
Although most valves are categorized as either sampling or switching, some valves combine
both functions and are termed "multifunction" valves.
6.3 Sampling Corrosive Materials
When dealing with harsh samples, such as chlorine and wet acid gases, valves made of
Hastelloy C-276 are recommended.