This is the 11th in a series of articles in our Vacuum Heat-Treatment Series. This part discusses vacuum valves, penetrations and flanges found on most vacuum vessels; where they are used, how they operate and a little about how they should be maintained.
Valves intended for vacuum service are subjected to a variety of special conditions (Fig. 1), ranging from high and ultrahigh vacuum levels to low, high and ultrahigh pressures, differentials in pressure and differentials in temperature as well as variable frequencies of mechanical operation. They can be supplied in a number of configurations: ball valves, gate valves, butterfly valves, needle valves, isolation valves, pressure-relief valves and control valves just to name a few. The type of valve in use is typically identified by its design or function, and each type can be actuated in a variety of ways (manually, electro-magnetically, pneumatically, electro-pneumatically or via electric motor). Position indicators and limit switches located on the valves are common. By Dan Herring
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Vacuum Heat Treatment is a comprehensive introduction and technical resource for vacuum processes and equipment, focusing on subjects that engineers, heat treaters, quality assurance personnel and metallurgists need to know. This book also serves as a practical guide by offering numerous tips and techniques on vacuum operation, vacuum controls, vacuum component operation and vacuum maintenance/repair. Each topic is covered in sufficient depth so that the reader understands why the subject is important and how to use this information in determining equipment choices, how furnaces should be run, how process recipes are designed, and what troubleshooting steps are needed.
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Dan Herring is president of THE HERRING GROUP Inc., which specializes in consulting services (heat treatment and metallurgy) and technical services (industrial education/training and process/equipment assistance. He is also a research associate professor at the Illinois Institute of Technology/Thermal Processing Technology Center.