MKS Granville-Phillips 203 Series, Инструкция по эксплуатации

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Operation
Series 203 Variable Leak Valve Installation and Operating Instructions
5
5 Operation
Leak rate is increased as the counter reading is increased. Twenty-seven
turns of the driver handle, or 270 counter numbers above the sealed
position reference number, changes the Leak from full closed mass
spectrometer leak tight to full open. Never increase the counter reading
more than 270 numbers or decrease below the number at which the Leak
seals. Exceeding these limits will not change the conductance but may
shorten Leak Valve life.
The counter has been preset so that the Leak Valve is sealed mass
spectrometer leak tight at a counter reading of about 0010. The counter may
be removed and reset to establish the reference for the fully closed position
at any value desired. It is also possible that the reference may change
inadvertently when the driver is removed. However, the sealed position can
readily be re-determined with a leak detector, and a new reference
established. Damage to sealing surfaces is prevented by a preset clutch.
6 Removing the Driver
The driver must be removed for bakeout.
6.1 Remove the name plate.
6.2 Turn the driver handle until the counter reads approximately 150 digits
above the previous sealing point to relieve all thrust on the nosepiece.
6.3 Remove the 6-32 x 1 5/8" retracting screw from the center of the worm
gear.
6.4 Support the Driver Assembly and remove the four symmetrically
placed 8-32 x 1" driver mounting screws and washers located on the
tubulation side of the Leak Valve.
6.5 Place Driver Assembly in a clean polyethylene bag.
6.6 Attach the bakeout clamp to the nosepiece of the Leak Valve and
retract the nosepiece until it contacts the bakeout clamp.
6.7 The Leak Valve is now ready for bakeout.
7 Bakeout
High temperature bakeout of a system will greatly decrease the required
pump-down time for pressures below 1 x 10
–6
Torr (1.33 x 10
–6
mbar,
1.33 x 10 –4 Pa). Leak Valves are designed to withstand repeated bakeout to
450 ° C if the driver is removed and the valve is held open with the bakeout
clamp.
Do not subject the valve to high temperatures any longer than necessary.
Excessive baking will shorten the useful life of the valve. Bakeout should
only be done when the pressure on the interior of the valve is below
1 x 10
–4 Torr (1.33 x 10 –4 mbar, 1.33 x 10 –2 Pa) so that oxidation is kept to
a minimum.