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…
Sometimes it is necessary to transport sample from some distance to the analyzer. There is no inherent problem in doing this, unless the sample is subject to condensation (see “Sample Conditioning” article); the analyte is unstable; or the interconnect tubing material might exhibit chemisorption properties. Recommended tubing: Bev-A-Line IV (Polyethylene liner with ethyl vinyl acetate…
The term “sample conditioning” simply means the preparation of the gas sample containing your analyte to render it suitable for introduction into your gas analyzer. This is usually less of a consideration in ambient air monitoring applications than in source monitoring applications. When sampling from a source such as an industrial process, utility stack, or…
Back in the 1970s, many multi-point systems were being deployed, for monitoring carbon monoxide in parking garages and vehicular tunnels. Since long and otherwise exposed sample tubing runs needed to be installed, copper tubing was used. Because CO is not very reactive, and copper tubing is both flexible and robust, this was a preferred choice.…
In the field of gas detection, an “interference” is an unwanted response on your instrument, caused by some chemical other than the target analyte. Generally speaking, no analytical method—using any technology—is completely specific. Thus, it is important for instrument manufacturers to document these interferences to the best of their ability. Here at Interscan, we…
Fair question. How would you respond to such a query, if pressed by an employee? In fact, this sort of thing does come up, and here’s an example: In the early days of instrumentation-based toxic gas detection, the steel industry was a major part of the business, and carbon monoxide was the biggie. Large amounts…
