More on bump testing in gas detection

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…

Watch Out When Using A Zero Filter

Especially when doing low range work, it is important to make sure that your instrument is properly zeroed. Ideally, zeroing should be performed with a certified zero gas. However, mostly since it adds another step to the calibration process, this practice has somewhat fallen out of favor. The alternative to a zero gas requires that…

Calibration of hydrogen peroxide and peracetic acid gas analyzers

ASTM promulgates numerous publications under the banner “Atmospheric Analysis Standards.” One of the most widely cited is ASTM D3249, entitled “Standard Practice for General Ambient Air Analyzer Procedures.” Section 8 of this document covers calibration. You can tell that the standard was written by knowledgeable instrument people, for several reasons—not the least which is the…

Calibrating and testing direct-reading portable gas monitors

This material is presented on OSHA’s website as a Safety and Health Information Bulletin [SHIB 09-30-2013]. The content was written by the International Safety Equipment Association (ISEA). We post the article here, and offer commentary in maroon type… The information in this Safety and Health Information Bulletin (SHIB) provides workers and employers guidance on calibrating…

Perm tube tech: Rigorous discussion of “K” value and best way to calculate gas concentration

Time to get seriously techie on perm tube calibration fundamentals… This is a detailed analysis of the so-called “K” constant used with permeation devices, to enable the calculation of the emitted gas concentration.  Over the years, many of our customers—and Interscan’s own technical personnel—have been frustrated by the confusing and inconsistent documentation on this matter…

Permeation devices

How To Use Permeation Devices (courtesy of VICI Metronics, Inc.) Permeation devices provide an excellent method of producing known gas concentrations in the PPM and PPB level for calibration of analytical instrumentation. The basic requirement of any calibration system used with these devices is to maintain the permeation device at a constant temperature in a…