At the time of publication of this method, mercury barometers and non-tilting mercury McLeod gauges were the only primary standards available for pressure measurement. Since that time, non-mercury containing primary standard pressure devices have been developed, such as high precision dead-weight testers, etc. Additionally, electronic pressure measurement devices have been in use for a number of years and have shown to be reliable and accurate when used in these applications. Due to the strong push within ASTM to remove or provide alternatives to mercury in the standard test methods, we believe that rewording of specific sections referring to the mercury containing primary standards is in order to allow for the use of other, non-mercury containing devices as primary standards for purposes of pressure measurement and calibration of secondary gages/sensors.
Keywordsatmospheric equivalent temperature (AET); boiling range; distillation; vacuum distillation;