LoPro™ two-stage valves soft start the system in two easy steps without the use of secondary bypass lines, which clog easily and are expensive to maintain. In the first stage, the bypass valve pumps down slowly from atmospheric pressure to a vacuum pressure specified by the end-user. In the second stage, the main valve opens, allowing use of full pumping speed. The main valve is smaller, lighter, and lower in cost than similar competitive valves while offering improved reliability and increased uptime. The square cap design is easy to assemble and maintain.
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.