Surrogate Calibration

The term “surrogate calibration” refers to a practice in instrument calibration whereby a standard different from the entity to be measured is utilized. For example, thermal flowmeters are based on convective heat transfer effects, and can be calibrated at ambient conditions on a specific gas, and then be used at process conditions to make accurate…

Can the detector be calibrated at one concentration to cover the entire range? Since the response is linear, I think the answer is yes. Please confirm. Thanks.

The answer to your question is YES. You are correct in noting that the response of our instruments is linear. More than that, electrochemical voltametric sensors (such as we use) are inherently linear, with no electronic compensation required. However, for optimum accuracy in most applications, it is best to calibrate the instruments at a concentration…

Calibration Basics

Introduction It is quite unlikely that you will ever use an absolute method for gas detection. Rather, you will employ any one of dozens of “relative” [or “reference,” but not necessarily EPA Reference] methods—that is, methods that use a sensor to produce some electrical output that must be calibrated against a known standard. Then, its…

In Search of Zero

As discussed in the Calibration Basics Knowledge Base article, Interscan’s gas analyzers, and virtually all other direct-reading gas analyzers are not absolute methods. Rather, they employ “relative” [or “reference,” but not necessarily EPA Reference] methods. That is, methods that produce some output that must be calibrated against a known standard. Generally, these units must also…

EtO Instrumentation Calibration and Surrogate Calibration Techniques

Written in response to a particular inquiry, this article is posted since it is of general interest. Calibration is a very important issue. One of Interscan’s competitors recommends calibrating its EtO monitor with CO (Carbon Monoxide). There is nothing wrong with using CO to calibrate an analyzer, assuming it is a CO analyzer that you…