Wednesday, March 18, 2009

How do pocket H2S monitors work?


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This post will give you a brief idea about how a pocket h2s monitor works. A pocket h2s monitor is a small instrument that is meant to be used by a worker who is working in an area that may get poisoned with Hydrogen Sulfide gas (referred to as h2s). The H2S monitor is a small portable toxic gas monitor that has a clamp at the back, so that it can be easily clamped to the worker's belt or clothes. Alternatively it can be carried in a pocket. Intrinsically Safe versions are also available which means that they can be use din hazardous areas.

The pocket h2s monitor consists of a sensor (mostly electrochemical), associated electronics (including an LCD display, buzzer, light/LED) and a housing with the clamp. It has to be calibrated with a known concentration of h2s gas in air using a standard calibration gas bottle. Every time a worker enters a confined space area that may later on allow some traces of h2s inside, the worker has to carry this monitor, so that whenever h2s ingress happens, the h2s monitor will go off, sounding a loud buzzer and flashing a red LED as a warning to escape at the earliest.
Some versions can even transmit this alarm wirelessly to a remote control room or to a host unit that may be mounted in the area. This enables the workman's colleagues to rescue him, should he be unable to escape on his own.
A typical unit looks like this (shown above).