Image Credit: Nor-Cal Products, Inc.

Feedthroughs provide inlet and outlet tubes through the walls of a pressurized or vacuum system through a hermetic seal, while maintaining the integrity of the vacuum.  Different styles of feedthroughs are designed to transmit electrical current, fluids, optical signals, or mechanical motion through the walls of a vacuum system. 

Types of Feedthroughs

Feedthroughs can be broken down into four rough categories, each of which has a separate, more specific Search Form.

• Electrical feedthroughs transmit electrical current through the walls of a vacuum system.  This grouping includes coaxial, multi-pin (instrumentation), RF, thermocouple, and power feedthroughs.
• Fluid feedthroughs include nitrogen, air, and water devices.  Many of these feedthroughs are designed for use with cryogenic systems.
• Mechanical feedthroughs include linear, rotary, and linear / rotary feedthroughs.
• Fiber optic feedthroughs are available in unlimited cell, flange, and port designs and are ideal for a wide range of wavelengths. 

Specifications

There are many important specifications to consider when selecting a feedthrough.  These include:

• Mounting configuration
• Bearing type and position
• Shaft size
• Strength and termination features
• Residual magnetic field
• Pressure vacuum rating

For fluid feedthroughs, it is also important to consider the type of fluid to be passed through the system and the location of sealing stages to ensure system stability. Additionally, one must consider the diameter of the tubing that will be used and the diameter of the holes though which the feedthrough will be mounted.  

Mounting Configuration Options

Feedthroughs may be mounted to the housing of a chamber wall, or secured to a rotating shaft, using a number of methods.  Industry standard mounting flanges and custom configurations for the housing are available and custom lengths and designs can be provided for the shaft. Standard mounting configurations include threaded mount feedthroughs, nut mount feedthroughs, and flange mount feedthroughs. 

Standards

DSCC-DWG-87036 - CONNECTOR, RECEPTACLE, ELECTRICAL, SERIES SMA, FEEDTHROUGH, HERMETIC