Handheld gas detectors originated from wearable, battery-operated personal monitors. Early designs were usually set up to provide an alarm, in the event that the ambient concentration had exceeded some user-settable value. These instruments relied on diffusion sensors, and were most often set up to detect a single gas. A simple display showed the current gas…
Well-known as a disinfectant and sanitizer, PAA is produced by reacting acetic acid and hydrogen peroxide with an acid catalyst. PAA is always sold in stabilized solutions containing acetic acid, hydrogen peroxide, and water. Thus, the two other compounds are always present when PAA is being used. As it happens, acetic acid and hydrogen peroxide…
An introduction to the notion of interferences (those other gases in the environment that might respond in your instrument, thus “interfering” with your measurement of the target analyte), is given here. We continue the discussion on interferences by considering what can be done when you are confronted with an interference that is “unusual,” that is,…
Generally, there are two reasons that you would install a continuous gas detection system: Personnel safety and ventilation control. Of course, these factors are not always going to be mutually exclusive. We can lay out some precepts that should help… 1. Identify all the point sources of the toxic gas. These could be areas along a…
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…
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…
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…
Have you ever heard that “The solution to pollution is dilution”? This little aphorism is usually stated as a sort of inside joke, although it is public policy for radon in residences. We saw this principle in action when home builders affected by the Chinese drywall disaster would sometimes open all windows while the homes…
In most cases, the goal is to establish some sort of ventilation control, such that a balance can be achieved between energy conservation and guarding against toxic exposure. Carbon monoxide is usually chosen as the target analyte, unless the vehicular traffic will be largely diesel. While diesel engines do emit CO, it is less than…
In most cases, gas monitoring applications focus on a single gas. There may well be interest in detecting this compound at several points, but the end-user has determined that it has one particular target analyte. Sometimes, though, there will be two gases of interest. Common examples are hydrazine and nitrogen tetroxide; and carbon monoxide and…