NEW Agilent Variable Leak Valve CF 2.75 x CF 1.33, Movable Piston with Optically Flat Sapphire Assembly.

The Agilent Variable Leak Valve can be added to any vacuum system to establish an adjustable leak. It offers unprecedented control sensitivity and stability with leak rates as small as 1 x 10^-10 Torr-liters per second and provides an increasing rate of change as the size of the leak increases. This gives precise control in proportion to the size of the leak. The entire valve, including the drive mechanism, is bakeable to 450°C in either the open or closed position. This valve can operate in a vacuum range of atmosphere to below 10^-11 Torr (mbar) and has an Inlet Gas Pressure up to a maximum of 500 psi.

The valve is shipped in a closed, leak-tight position, lubricated and ready for installation. The main flange connection on which the variable leak valve is mounted mates with any 2 3/4 inch O.D. ConFlat flange. The Inlet gas connection is made through a standard 1 1/3in Mini-ConFlat flange. Leak rate adjustment is controlled with knurled knobs. To open a leak, the knurled knobs must be turned (together) counterclockwise, a minimum of two full turns. The valve is closed by turning the knobs (together) clockwise to the stop position against the handle.

The variable leak valve includes a movable piston with an optically-flat sapphire that meets a captured metal gasket. This forms a seal completely free from friction, seizing, and shear. The sapphire’s movement is controlled through a threaded shaft-and-lever mechanism having a mechanical advantage of 13,000 to 1. Spring washers keep this drive mechanism constantly loaded and eliminate the backlash usually associated with this type of device. This provides immediate response to small movements in the finger-controlled adjusting knobs. While some permanent compression takes place in the gasket each time a seal is made, the change is very slight. Return of the knob to a previous position will result in approximately the same leak rate. Both components of the seal mechanism (sapphire assembly and gasket assembly) are easily replaceable. The gasket life for unbaked systems is approximately 300 closures and only 20 to 30 closures for baked systems.

The Agilent Variable Leak Valve is perfect for applications that require an exact pressure selection to run a turbo in a specific range and maintain that pressure. The valve is designed to change the pressure selection to a specific applications' needs and then be moved to another selection easily and accurately. We offer all the necessary tools to make repairs and adjustments to this valve below in our Related Products section, including replacement parts such as the sapphire and gasket assemblies. Please refer to the Manual Section (pdf) below for more information on how to operate and maintain the Agilent Variable Leak Valve.

FEATURES

• Made for special purpose valve applications
  
• Vacuum Range from Atmosphere to below 10^-11 torr (10^-11mbar)
  
• Leak Rate that has no leak detectable on a helium mass spectrometer
  leak detector with sensitivity of 1 x 10^-10 std cc/sec
  
• Maximum Flow Conductance of 6 liters/min
  
• Bakeable to 450º C