Friday, September 5, 2014

Difficulties In Using Toxic Gas Detector

By Kerri Stout


Any gas that is harmful to our health is a toxic gas and we should avoid exposure to such gases. Use of toxic gas detector can aid in the detection since most of these gases are colorless and odorless. Early detection of these gases can save lives of many because precautionary measures are taken immediately and those affected given the medical attention before any serious damage is done to their bodies.

Industries install ducts for gases to move from one point to another. Sometimes chemical reactions in the ducts can cause them to start leaking releasing the dangerous gases in the atmosphere. Homes also have ducts installed for gas and sometimes harmful gases will be found in the ducts. Poor ventilation can also lead to carbon (II) oxide commonly known as carbon monoxide which is a killer gas in homes when using a fire place. It is necessary to have a detector that will warn of the impeding danger of a toxic gas presence.

The effectiveness of the detectors however may be subject to several factors and they may not warn you in advance at all times. This means that the systems set up to prevent high prevalence of the gases may not respond positively leading to diffusion of the gases to the areas with human presence. The failure to automatically shut down the ducts may lead to loss of lives and thus gaining an understanding as to why the systems may fail will help avert future recurrence of loss of lives.

Atmospheric air mixes with gases in the ducts reducing their concentration levels. If it dilutes the gas too much then the detectors will not be able to detect it. Highly diluted fluids will just show traces of a substance even if it is more than should be when not diluted. The level of the toxics could be high but only traces of it sensed due to high dilution

To solve the dilution effect problem, the sensitivity of the detectors should be increased such that even the lowest level of the gases is detected. The system should then have different alarm systems for different levels of the harmful substances. This prevents being caught unaware by catastrophes.

Duct stratification poses yet another challenge in detection. The ducts have bends, expansions and contractions. In an area of expansion the speed is low and build up of air increases, in that of contraction speed is very high and no build up of air. Taking levels from the two parts will give different results for that same gas flow.

The air velocity in ducts sometimes is too high moving up to 68 mph. In that speed air cannot be moving in a streamlined manner but a very turbulent one. A sensor that is not made to withstand these harsh conditions can fail to send an alarm. The detectors should be made in such a way that they must control the optimum reaction temperatures under strong air currents to prevent the sensors being hit directly.

Plant safety professionals recommend installation of the toxic gas detectors in the main supply duct. The detector will be able to shut off supply fans when installed next to the filters. Installation in this part solves the three challenges mentioned earlier.




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