The LoPro Two-Stage Valve is a normally closed, pneumatically actuated valve at both stages. Within the bypass valve, a removable, interchangeable small orifice is provided to allow for variable slow pump-down times. The standard bypass orifice diameter is 0.225”. An optional thumbscrew or micrometer head is available for the bypass valve for flow adjustment by stroke limitation. The formed 321 stainless steel bellows prevents outgassing, virtual leaks, and particle entrapment between bellows convolutions and extends the valve’s cycle life. The optimized bellows’ stroke length assures a longer cycle life while maintaining a high conductance.

The valve body is comprised of a high grade, corrosion resistant, 304 stainless steel using clean, tungsten inert gas (TIG) welding to ensure significantly fewer entrapment areas, resulting in less contaminant build-up. Select the LoPro Two-Stage Valve in a right angle or inline version and a port diameter of either 1, 1½, or 2 inches. Standard port interfaces include ISO-KF and CF flanges and weld stubs. Elastomer seal choices, for both stages of the valve, include Viton® or Chemraz®, which have a higher chemical resistance. Vacuum exposed parts are clean and free of lubricants. Options include an air solenoid for electropneumatic control and a limit switch for remote indication of the main valve’s position.