This is the sixth in a series of articles in our Vacuum Heat Treatment series. Here we continue our discussion of the types and characteristics of vacuum gauges and offers insights into which gauge should be used when working in a specific vacuum range.
Counting molecules is a job for vacuum gauges and it’s now time to understand the differences between these devices and when to use them. Recall first that the vacuum level in a vessel is determined by the pressure differential between the evacuated volume and the surrounding atmosphere (Table 1). The two basic reference points in all these measurements are standard atmospheric pressure (760 torr) and perfect vacuum (0 torr), so calculating changes in volume in vacuum systems requires conversions to negative pressure (psig) or absolute pressure (psia). By Dan Herring
A New Book by Dan Herring, The Heat Treat Doctor TM
NOW AVAILABLE! CLICK HERE
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.
Table of Contents
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.