Appendix C: Valve Orifice Selection General Information
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Appendix C: Valve Orifice Selection
General Information
The 649 controller is available in four valve orifice sizes. You should confirm that the valve
orifice in your 649 controller is the correct size for your application before you install it into your
system. The orifice is
not adjustable and is only replaceable at the factory.
This selection guide is valid with any valve plug seat material.
Checking the Valve Orifice Size
The valve orifice number is included in the model code number of your 649 controller. The
nominal flow rate range for the orifice numbers are listed in Table 10. Refer to
Appendix B:
Model Code Explanation
, page 49, for a description of the model code.
Valve Orifice Size
Orifice Size Model Code Entry (Z) Nominal Range (sccm of
N
2
with 760 Torr
[101.3 kPa] ΔP)
A A <100
1 1 200
2 2 1000
3 3 5000
Table 10: Valve Orifice Size
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