LoPro™ Soft-start Bellows Vacuum Isolation Valve
Overview
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.
- NW25 - NW50
- Two-stage with adjustable conductance for variable pump down speed
- 1,000,000 cycle rating (clean environments)
- Reduces particulate contamination during early turbulent pumpdown
Products
Configuration Options
Please see the LPV2 datasheet for available product options.
Specifications
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TypeLow-profile, Two-stage, Soft-start, Bellows-sealed Isolation Valves
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Vacuum RangeAtmosphere to 1.0 x 10-9 Torr
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Port SizeNW25, NW40, NW50
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Helium Leak Rate1.0 x 10-9 std cc/sec
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Cylinder VolumeMain cylinder: 1.2 - 6.4 in3, depending on configuration
Bypass: 100 in 3 -
Cylinder Air Pressure90 psig ±30 psig
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Limit Switch Rating5A - 250 VAC
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Single Pole, Single Throw5A - 30 VDC
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Blow-By PressureMain: 80 - 45 psi, depending on configuration
Bypass: 45 psi -
Actuation TimeMain: 40 - 160 msec to open, 90 - 220 msec to close, depending on configuration
Bypass: 100 msec (both) -
Maximum Internal Spring Closing Pressure38 - 60 psia, depending on configuration
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Maximum Bakeout Temperature150°C
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Typical Life1,000,000 cycles
Features
Two-Stage Valve Components
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.
304 Stainless Steel Valve Body
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.
Resources
Literature
- LoPro™ Two-Stage Compact Vacuum Soft-Start Valves (333.8 kB, PDF)
Manuals
- MKS LoPro 2-stage Valve Manual (213 kB, PDF)
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