MKS MF1 - Troubleshooting; Table 7 Troubleshooting

Chapter 8: Maintenance
103
Troubleshooting
Symptoms Possible Cause Remedy
No output or overrange at zero
(after warm-up)
Improper cable
Valve override function applied
(Mass flow controller)
Electronics malfunctioning
Check cable for type
Disconnect / disable valve
override
Return for service
Unit indicates a negative flow
Unit installed in gas stream
backwards
Reinstall unit in proper flow
direction
Controller does not track set
point.
Improper zero adjustment
Improper grounding(s)
Zero meter output
Check all ground connections.
Check signals, if possible
directly at the unit’s connector
Controller does not function
Electronics malfunctioning
Valve sticking, clogged,
contaminated, corroded.
Shutoff valve upstream or
downstream closed
No inlet pressure
Return for service
Check compatibility of the
process gas with materials
wetted (corrosion is typically
also visible inside the process
fittings)
return for service
Open shutoff valve first, then
apply again setpoint to the
unit.
Regulate inlet pressure
Oscillation Supply pressure unstable, e.g.
defective pressure regulator.
Supply pressure too high
Check manufacturers’
specifications
Reduce upstream pressure
Excessive closed conductance Inadequate valve preload
Valve seat elastomer damaged
return for service
Check compatibility of process
gas with seat material
return for service to replace or
change valve seat elastomer
Unit does not achieve full flow
Upstream pressure too low
Excessive valve preload
Valve seat disc damaged, e.g.
swollen
Increase upstream pressure
return for service
Check compatibility of process
gas with seat material
return for service to replace or
change valve seat elastomer
Table 7 Troubleshooting