MKS Mass-Flo 1179A, Инструкция по эксплуатации

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Chapter Seven: Troubleshooting How To Adjust the Valve Preload (MFC only)
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12. Slowly turn the centershaft while monitoring the DMM: clockwise rotation increases the
current required to open the valve; counterclockwise rotation decreases it. Adjust to a
target value of 25 mA, except for 10, 20, and 50 sccm units containing Viton, Buna-N,
or Neoprene elastomers which require 20 mA preload.
Note
Always make adjustments by turning counterclockwise first and then
turning clockwise to the proper setting. This procedure ensures that the
adjustment will remain fixed when you retighten the lock nut.
Caution
Do not overturn the centershaft! Excessive turning may damage the
plug and cause poor closed conductance and flow control.
13. Holding the centershaft in place, re-tighten the jam nut. As you tighten the jam nut,
monitor the DMM to ensure that the current remains within 1 mA of the target value.
14. Change the set point input signal to 0.0 Volts.
15. Monitor the MFC output to verify that the valve closed conductance is within
specification.
Refer to Appendix A: Product Specifications, page 57, for the valve closed conductance
specification. If the valve fails to meet the closed conductance specification, return the
unit to MKS for service.
16. Change the inlet pressure to the minimum expected in use.
17. Change the set point input signal to 5.0 Volts (100% of full scale).