MKS 640A/641A - Table 14: Valve Type; Table 15: Seal Material Selection

Appendix D: Model Code Explanation Model Code Descri
p
tion
69
Valve Type (Z)
The 640 Series controller has a normally closed valve, designated by a single number.
Valve Type
Valve Order Code
Normally Closed 1
Table 14: Valve Type
Seal Material (Q)
The control valve can use either one of a variety of elastomer seal materials, or an all-metal seal.
Seal Material Selection
Seal Material Order Code
Kalrez K
Metal M
Viton V
Table 15: Seal Material Selection