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Home  > Valves > All-Metal Valves

All-Metal Valves
Angle & Inline Specifications

MDC bakeable all-metal angle and inline valves are designed for use in ultrahigh vacuum environments where elevated temperatures preclude the use of elastomers and low temperature gasket metals. These valves provide reliable high temperature seals from atmospheric pressures to below 10-11 Torr.

Wherever possible, bonnet gasket seals have been eliminated in an effort to minimize the number of potential leak paths. Valves fitted with bonnet seals have been so designed to facilitate gasket replacement. The size and orientation of the valve body ports on bonnet fitted valves precludes gasket removal through its ports. 

All-Metal Valves. Angle and Inline

When operated at ambient temperatures, all-metal valves provide hundreds of leak free cycles between routine poppet gasket replacements. In high temperature applications, life cycles are inversely proportional to the bakeout temperatures. 
When operated at the maximum bakeout temperature of 450°C, the poppet seal gasket life is reduced to approximately 50 open/close cycles.

Seal Design
A vacuum seal is made by pressing the poppet OFE copper gasket onto a conical stainless steel knife edge seat as depicted in the diagram at top-right. The sealing pressure deforms the copper gasket, which conforms to the conical knife-edge seat. During thermal cycling the valve’s loading mechanism counteracts component differential expansion to maintain a uniform pressure necessary for seal integrity. 

Poppet Gasket Replacement
Poppet gasket replacement for the 1-1/2" and 2-1/2" all-metal angle valves must be done by removing the valve from the system, as these two valves have welded bonnets. Once detached from the system, gasket replacement is easily accomplished by inserting a standard blade screw driver into the bottom port and unscrewing the copper gasket, which is then extracted through the side port of the valve. The 3/4" angle valve and all inline valves are fitted with bonnet seals and do not require complete removal from the system for gasket replacement. Gasket removal and replacement is performed by detaching the bonnet flange from the valve body. Once the bonnet has been opened the gasket is easily detached by unscrewing with a standard blade screw driver.

Seal Torque
The first seal or closure in an all-metal valve causes plastic deformation of a virgin copper gasket leaving a permanent impression. This first closure is made at the factory and shipped to the customer in a ready to install sealed condition. Upon breaking this seal, resealing can be accomplished by torquing the valve according to the “Poppet Sealing Torque” data found in the specifications chart. To aid in the process of subsequent seal cycles the top of each valve body is fitted with a radially graduated vernier plate. The vernier plate provides a visual cue for previous and subsequent cycle or torque positions.

Valve Compatibility
MDC offers Varian and Vacuum Generators (VG ) compatible all-metal angle and inline valves. The Varian compatible valves have been labeled as "V" in the valve type column found in each product table. Vacuum Generators compatible valves are identified by a "VG" designation in the valve type column. Compatibility is defined herein as the ability to replace or interchange Varian and/or Vacuum Generators valves with MDC all-metal valves. Compatibility is limited to valves fitted with Del-Seal™ CF port flanges and exclusively to the port to port dimensional  characteristics. In other words, the dimensions from any valves’ flanged port centerline to the opposite ports’ flange face are direct equivalents to Varian and VG valves. Other MDC all-metal valve dimensions may vary from those found on Varian and Vacuum Generators products. The "T" designation in the valve type column pertains to valves designed for either tube weld installation or custom flange attachment.  

 
Standard Features
  • UHV compatible to 1x10-11 Torr
  • Manual actuation
  • Hundreds of seal cycles per gasket
  • Replaceable OFE copper poppet gasket
  • High temperature service to 450°C
  • 300 Series stainless steel construction
  • Stainless steel bellows sealed actuator
  • High conductance design


Specifications
Material 
 Flanges 304ss
 Valve Body  304ss
 Bolts  300ss
 Gaskets, Poppet and Bonnet  OFE Copper
Port Fastening
 Bolt Type Silver plated 12-point and socket head bolts
 Nut Type Hexagonal nuts
Vacuum
 Range  1x10-11 Torr
 Leak Test 2x10-10 cc/sec of He
Poppet Sealing Torque
 3/4" Valve, First / Subsequent Seals 7-10 / 6-7 lb-ft
 1-1/2" Valve, First / Subsequent Seals  4-8 / 4-7 lb-ft
 2-1/2" Valve, First / Subsequent Seals 7-10 / 6-7 lb-ft
Temperature Range
 Closed / Open 300°C / 450°C


 All-Metal Valves - Angle
For product listing, features and specifications click on links below
 3/4 inch Angle Valve
 1-1/2 inch Angle Valve
 2-1/2 inch Angle Valve


 All-Metal Valves - Inline
For product listing, features and specifications click on links below
 1-1/2 inch Angle Valve
 2-1/2 inch Angle Valve

 

 

 


 Related Topics
 Angle and Inline Valves
 All-Metal Angle and Inline Valves
 Variable Leak Valves- Fine Leak
 Variable Leak Valves- Precision Leak

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