MKS 649A - Appendix C: Valve Orifice Selection; General Information; Checking the Valve Orifice Size; Table 5: Valve Orifice Size

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 5. 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 1 ATM ∆P)
A A <100
1 1 200
2 2 1000
3 3 5000
Table 5: Valve Orifice Size