Humidity is a tough measurement. It’s very hard to get a repeatable measurement with low uncertainty. This post discusses seven best practices that will help you make a more accurate, repeatable, and reliable humidity measurement. The recommendations are primarily based on the NPL document, “A Guide to the Measurement of Humidity.” 

“Please tell me how to map this chamber!” This is a plea we hear at every Vaisala current Good Manufacturing Practice (cGMP) seminar. The question deals with environmentally controlled chambers, everything from small refrigerators or freezers, to walk-in chambers or even large warehouses regulated under cGMP rules and guidelines. Attendees who ask the question are usually more interested in how to map a chamber for maximum reliability or effectiveness as opposed to meeting the U.S.