MKS Granville-Phillips 203 Series, Инструкция по эксплуатации

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Installation
4
Series 203 Variable Leak Valve Installation and Operating Instructions
3.6 Temperature
The conductance of the Variable Leak is slightly temperature dependent
and will vary if the ambient temperature varies. Bakeout temperatures up to
450°C may be used, provided the driver is removed and the leak is held
open by the bakeout clamp. Do not bake the leak with the driver attached
to a temperature higher than 70°C.
3.7 Vacuum Connections
A wide variety of connections are available to make any Variable Leak
adaptable to existing or new systems. Metal tubulation or flanged
connections may be ordered.
Metal tubulation is of Type 304 Stainless Steel in V4 inch 00 x 0.035 inch
wall. The Stainless Steel tubes may be welded to any other 300 Series
except the free machining grades.
Rotatable flanges made of Type 304 Stainless Steel, heliarc welded to Type
304 tubulation, are available. Both the 2¾ inch CuSeal
®
and 115/16 inch
Mini-CuSeal ® flanges are manufactured to geometries licensed by Varian
Associates, Inc. Each of the Flange styles use a different replaceable OFHC
copper gasket between two mating flanges, and type 18-8 bolts, nuts, and
washers, Also available are versions using Cajon
® VCR and VCA fittings.
4 Installation
Use every precaution to prevent contamination from entering the Leak.
Keep plastic caps or rubber stoppers on the valve ports until the valve is
ready to be connected to the system. Do not use cork or adhesive tape.
When the unit is not installed, the valve should be left slightly open and
placed in a clean polyethylene bag as protection against contamination.
For inlet pressures less than one atmosphere either port may be connected
to the gas source. For pressures greater than one atmosphere the gas source
must be connected to the center port, Port S, to prevent damage to the valve
diaphragm.
All welding operations must be done with an inert atmosphere inside the
valve to prevent the formation of oxide contamination which could enter
the valve and cause failure. Heliarc welding with better than 99% pure
argon inside and a 3 to 4 minute purge is satisfactory.
When flange connections are supplied on the Leak Valve, mating flanges of
the same diameter and style must be provided on the system. Each design
uses a specific OFHC copper gasket. Insert a new, clean gasket between
mating flanges using care not to mar the gasket surfaces. Uniformly tighten
Type 18-8 bolts and nuts with washers until the outer flange surfaces are in
contact. Intimate contact is important for good mechanical strength.