MKS Instruments UK Ltd
V2000-C/E Hardware Manual – SP102005.102 March 2013
32
Removing the inlet valve assembly
The UniBloc
™
inlet-
valve assembly bolts directly onto the RGA chamber inlet flange with a standard CF40 (2.75”
CFF) gasket. It is held in place by special ¼” x 28, socket head, silver-plated bolts that run through its length
from the process chamber end of the inlet valve. To access these bolts, the process chamber end of the
UniBloc
™
must be exposed.
On the RGA face of the UniBloc
™
is the ceramic coupling socket that mates with the gas inlet tube on the closed
ion source. When the UniBloc
™
inlet is removed, care must be taken pull it straight away from the RGA
chamber, not allowing it to move radially, or damage will be done to this critical component or its mounting
hardware.
To remove the UniBloc
™
inlet:
1.
Shut down the Vision 2000C/E system by following the instructions on Page 27.
2.
Remove the heater jackets and the Microvision2.
3.
Remove any connection to the process chamber side of the UniBloc
™.
4.
Remove the six
¼” x 28 bolts that are recessed into the flange of the UniBloc, taking care to
support the inlet when the last two bolts are freed.
5.
Pull the inlet straight away from the RGA chamber, taking care not to put pressure on the ion
source coupling components.
6.
If the ceramic coupling is removed, take care to note the details of its assembly (ceramic on
flange, retainer ring on ceramic, screws through springs and then through retainer ring into
flange).
Refitting the inlet valve assembly
All components must be scrupulously clean for UHV service prior to reassembly.
If you removed the ceramic coupling-socket, refit by it reversing the procedure followed during its removal. For
system with compression springs, note the following tightening procedure: tighten these screws until the top of
the screw head is flush with the top surface of the ceramic coupling (springs will be very loose). Then tighten all
screws 2 full turns more (0.8mm). The springs should now provide pressure that holds the ceramic securely, but
allows it to slide freely with slight pressure.
To re-fit the UniBloc
™
inlet, reverse the removal procedure. Take care to ensure the ceramic coupling socket
mates correctly with the gas inlet tube on the closed ion source. Tighten the special bolts carefully, gradually
tightening them in stages so that the tension is developed evenly all the way around the flange. An over-
tightened, stripped bolt is a very costly and inconvenient mistake to repair.
Once the Vision 2000C/E system is re-assembled it must be leak checked before re-fitting the heater
jacket.
Vision 2000C/E electronics
The RGA control unit (Microvision2) supplied as part of your Vision 2000C/E system is designed specifically to
operate with a closed ion source. No damage will be caused to the analyser or the electronics if a replacement
standard RGA control unit is fitted, but the performance will be dramatically reduced. This is of particular
relevance to customers who operate more than one MKS RGA.
Turbo pump maintenance
The bearings in the turbo pump need to be re-lubricated, periodically. The period will depend upon the
corrosiveness of the process gases being sampled, the flow rate (significantly higher for 4-valve systems) and
the number of hours per day spent sampling process gas. Consult the turbopump manual supplied with your
system for further details.
Mass spec maintenance
The only routine maintenance required by the quadrupole is to change the filaments. The filaments will wear out
in time and changing filaments is fully described in the Microvision2 manual.
