Perhaps the most well-known example of two point calibration involves liquid-in-glass thermometers, the most popular of which used to be mercury thermometers. That device was invented by physicist Daniel Gabriel Fahrenheit in Amsterdam (1714). Brilliant in its simplicity and accuracy, it took advantage of important physical constants: The predictable expansion of mercury as a function…
One definition of “low concentration” would put it at doing work below 1 ppm. Another would consider that any measurements below the usual regulatory values would be deemed “low concentration.” Either way, more care has to be taken in such work. Here are a few tips: 1. Be very sure of your calibration standard. While technology…
Hydrogen Peroxide Hydrogen peroxide monitoring in the SPD has been discussed in two prior Gas Detection Knowledge Base articles. The first article served as an introduction to the subject, some years ago, when hydrogen peroxide gas plasma sterilizers were new. As you may recall, these sterilizers came into the marketplace with at least the implied…
PLEASE NOTE: We are NOT the manufacturers of the swabs, and we do not perform ethylene oxide sterilization. During the great COVID-19 pandemic, millions of people are being tested to see if they are infected with the virus SARS-CoV-2. The test involves a sample being taken deep into a nasal cavity, using a medical…
In most gas detection applications, you are dealing with either the ambient open air, source effluent of a very high volume, or a confined entry location which still has no practical limit of the air sample available. In certain cases, however, an application may arise in which the available sampling volume is limited. Most of…
The subject of bump testing was introduced in this Knowledge Base article. While bump testing is primarily a coarse functional test, rather than a true calibration, it is a common practice—especially for confined entry instruments. If many units need to be screened, the time savings of bumping over calibration can be significant. However, we are…
We have long advocated that government and industry refrain from using the metric-looking units—typified by the infamous milligrams per cubic meter—when discussing gas concentrations. The obvious reason is that the volume of a gas is affected by temperature and pressure. Thus, a concentration reading in mg/cubic meter is only valid for a particular set of…
In our Gas Detection Applications Primer, we describe the notion of recommended and regulatory limits, as applied to toxic gases in the workplace. Discussed therein are the OSHA parameters of Permissible Exposure Limit, Action Level, and Ceiling Value. If this “Action Level” is detected during initial monitoring of the occupancy in question, that is the…
