16.7.6 Troubleshooting
Auto-Zero boards should be either replaced or repaired at the factory. The following is a
list of potential sources of operator difficulty when improperly utilizing the Auto-Zero
featur
e. Each item on the checklist should be investigated during troubleshooting:
16.7.7 Checklist
1. Was the MFC warmed up for 60 minutes prior to zeroing?
2. Is the MFC being operated in the position for which it was calibrated?
3. Was the Auto-Zero allowed the 90 second delay for stabilization?
4. Is the setpoint above 1% of full scale (for units with Auto Shut-off(A))?
5. Was the Auto-Zero board installed correctly?
6. Is there gas flowing when the MFC is off?
7. Is the MFC meter zero beyond the ±4-5% range of automatic zero and in need of repair
or recalibration?
8. Has the Auto-Zero MFC been off-cycled regularly to ensure best performance?
9. Is the Auto-Zero allowed to operate for a minimum of 3 minutes to re-establish zero?
16.7.8 Disabling Auto-Zero to Establish True Zero
1. Apply a setpoint of 2% or more.
2. Turn on the MFC (pin J open circuited or 5VDC applied)
3. Isolate gas flow or evacuate the MFC.
4. Unplug the MFC
5. Replug the MFC and allow 10 min. warm-up (assuming previous 60 min. warm-up)
6. Establish the normal operating temperature and attitude of the MFC.
The true zero should now appear on the flow readout. If the true zero is beyond the
operating limits (±4-5%), then the following re-zero procedure can be used. (Re-zeroing is
advised if true zero is more than ±1% out.)
32
©2005 Celerity
, Inc.
#199-001-0006 REV
.F 4/05
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
To Next Page
Loading...
Need help?
General
