HP 5890 SERIES II Service Manual page 246

Any intermediate position of the rotor may result in an interrupted flow path which
could cause damage to the valve or other components in the chromatograph.
The letter of the rotor type stamped into the valve body indicates the rotor installed in the particular
body.
P Polytetrafluorethylene (Teflon rotor) may be used from 0 to 175 degrees C. (This low tempera-
ture valve may be unmarked - no" P" ).
PT High Temperature (polyimide rotor) may be used from 100 to 300 degrees C. (This " high tem-
perature"valve may be marked with " PT" , or just " T" ).
The rotor seat of the valve body is a highly polished conical surface. This finish precludes adsorption of
most GC samples. Additionally, with a properly seated rotor the polished surface will prevent leakage
around the rotor and between non- selected ports.
The rotor assembly is essentially a one- piece stainless steel part with an integral molded and ma-
chined conical hub and several parts necessary for proper seating. The sample will contact either Te-
flon (low temperature) or polyimide (high temperature) as well as the stainless steel of the valve.
The rotor fits precisely into the body and nests in the conical seat. It is held in place by a preloaded
assembly.
The grooves in the rotor determine the paths between specific ports and run in a transverse fashion
across the rotor. The index pin prevents rotation beyond either stop of the index lip. Valve ports are
connected by the grooves only when the index pin is close to or against either stop of the index lip.
Any intermediate position results in shutoff of flow through the valve and possible valve damage if left in
this position.
General Purpose Valves (GPVs)
The standard general purpose valves have 1/16- inch zero dead- volume fittings. They may be classi-
fied by the number of ports they contain and their useful temperature range. The valves with Teflon ro-
tors may be used in the range 0 to 175 degrees C; whereas, the valves with polyimide rotors function
best in the range of 100 to 300 degrees C. Both types of valves are available with 6 or 10 ports, de-
pending on the desired application.
Teflon rotors are not interchangeable with polyimide rotors in the same valve body. Because of the dif-
ference in the operating temperature ranges, do not mix these two valve types in the same system.
The life of any valve is shortened, if not used within its specified temperature range
1/16inch Teflon rotor valves...............0to 175 degrees C
1/16inch polyimide rotor valves..........100to 300 degrees C
Adjustable restrictor valves.........ambientto 175 degrees C
The HP 5890 was designed to accept valves heated in their own compartments because valves operate
best at a constant temperature. It is important to realize that, when a valve is inside a gas chromato-
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CAUTION
CAUTION
Temperature Ranges for Liquid Sample Valves
SVC 7- 10