How To Adjust the Valve Preload (MFC only)
Chapter Seven: Troubleshooting
50
How To Adjust the Valve Preload (MFC only)
Warning
Before performing MFC valve adjustments, you MUST purge
your process equipment and the MFC with an inert gas, such
as argon or nitrogen, and isolate the MFC from toxic and
hazardous gases. Use an inert surrogate gas while adjusting
the valve preload as a safeguard against inadvertent
exposure to any toxic or hazardous gas. A release of
hazardous or toxic gas could cause serious injury. If
necessary, remove the MFC from the process equipment to
adjust the valve.
Questions concerning the safe handling of toxic or hazardous
gases may be answered by consulting your corporate policy,
a government agency such as OSHA or NIOSH, or experts
familiar with your process gas.
MKS assumes no liability for safe handling of toxic or
hazardous gases.
Caution
All valves are adjusted at the factory for proper leak integrity and
flow control response. Adjust the valve only if the Troubleshooting
Chart, page 49, recommends that you do so.
This procedure requires the following equipment:
•
Any special safety equipment necessary to handle the gas in use
•
3
/
32
” allen wrench for retaining screws (4-40 socket head cap screws)
•
3
/
16
” allen wrench for the centershaft
•
9
/
16
” wrench for the lock nut
•
Digital Multi Meter (DMM)
