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How often do I need to calibrate my gas monitor?

This is a controversial subject. OSHA would have you calibrate your gas detector before each use. In practice, our customers come up with their own intervals. If the gas monitor is used infrequently, say once a month, it should be calibrated every time to give you confidence that the unit is going to respond as it should. If your company uses its detection device a few times a week, then our customers have told us they do an occasional bump test and calibrate less often. This is consistent with information from the president of RKI Instruments, a gas detector manufacturer, who writes in an article for the National Safety Council that folks who “bump test” (subject their gas monitors to the gases they are supposed to detect in order to make sure they will register) before each use, may extend the calibration cycle to “three to six months for instruments that successfully pass the bump gas test”. To read more, click here.

How do I clean my gas monitor?

You should follow each manufacturer's directions. For BW Honeywell Gas Detectors the manufacturer recommends the use of a soft damp cloth. The only approved cleaner is ACL Staticide. You should avoid exposing the sensor screens to moisture. DO NOT use computer keyboard air dusters to clean debris from sensor filters or products such as EconoClean, WD40, etc. as these will destroy the sensors.


What is Oxygen Deficiency?

The most widely accepted definition is that air is oxygen deficient whenever concentration is less than 19.5%. This occurrence is often associated with confined spaces, unventilated cellars, sewers, wells, mines, ship holds, tanks, and enclosures containing inert atmospheres. Typical causes are displacement, microbial action, oxidation, combustion and absorption.


What is a Confined Space?

In terms of OSHA and NIOSH safety requirements, a "confined space" refers to an area whose enclosed environment and limited access make it dangerous to people working there. Anywhere access or egress is limited, or that may contain hazardous atmospheres (too low or enriched oxygen levels, toxic or flammable gases) will likely be classified as a confined space for workers. Confined spaces can be above or below ground level. Examples of confined spaces include inside airplane wings, tanks, pipes and sewers, ventilation shafts, electrical service rooms, vats, and silos.


Gas Detection Acronyms:


  • LEL - Lower Explosive Limit. The minimum concentration of a combustible gas or vapor in air which will ignite if a source of ignition is present
  • UEL - Upper Explosive Limit. Most, but not all, combustible gases have an upper explosive limit which is the maximum concentration in air which will support combustion. Concentrations which are above the U.E.L. are too "rich" to burn.
  • PPM - Parts Per Million (toxic & VOC)
  • %VOL - Percent by volume (oxygen)
  • VOC - Volatile Organic Compounds (PID)
  • PID - Photo Ionization Detection (VOC)
  • TWA - Time Weighted Average (toxic gases)
  • STEL - Short Term Exposure Limit
  • IP - Ionization Potential & Ingress Protection
  • IS Rating - Intrinsic Safety (UL, CSA)
  • T90 - Time sensor needs to reach 90% full response


What are the three basic kinds of atmospheric hazards?

  • Oxygen (deficiency and enrichment)
  • Flammable gases and vapors
  • Toxic contaminants