Two-stage Series
Soft Start Bellows-sealed Isolation Valves

photo - MKS Two-stage Soft Start Bellows-sealed Isolation Valve

MKS Two-Stage valves achieve a soft pumpdown and vacuum system isolation in one common housing. A small bypass valve is integrated into the main isolation valve, simplifying setup and reducing costs. With the integrated soft pumpdown feature, turbulent flow is diminished preventing contamination buildup and damage. The bypass valve can be user adjustable by selecting a micrometer or thumb screw adjustment option. Additionally, a fixed flow orifice can be sized for the application that is housed internal to the valve to prevent unwanted adjustment. These legacy valves are supported by MKS for configurations not supported by the LoPro product line. For increased cycle life and reduced size, please see the MKS LoPro Two-Stage products.

Features & Benefits:

  • Two valves integrated into one common housing
  • Optional adjustable conductance for variable pumpdown speed
  • Eliminates the need for small bypass lines
  • Reduced turbulence and contamination during pumpdown


MKS Two-Stage Valves are best suited for high vacuum applications, specifically semiconductor or optical processing for which a cleaner environment is necessary. With the integrated slow pumpdown feature, turbulent flow is diminished, reducing particle contamination.


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Two-stage ValvesQuote Only

Documents & Downloads:

2-stage Valve data sheet

Need help?

Contact an Application Specialist by sending an email to MKS Instruments or call 303-449-9861.