When is a part-per-billion (ppb) NOT a part-per-billion (ppb)?

As if it weren’t bad enough that clueless environmental authorities try to impose their ignorance on the field by using so-called “metric” units of gas concentration, another trap may be lurking for you. Everyone around the world agrees that a part-per-million (ppm) equals 10–6. Unfortunately, since everyone around the world does not agree with what a…

Minimum Detectability

Minimum Detectability” is one of those instrumentation terms that is used frequently, but is seldom defined. Indeed, even though you will encounter this term on many data sheets, its definition does not appear in any of the usual learned references, including Process Instrumentation Terminology, ANSI/ISA—51.1—1979(R1993) and Standard Terminology Relating to Sampling and Analysis of Atmospheres,…