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How to use H2S Monitor at work site

I have seen them on pant pockets,  to hard hat, the proper location of a H2S Monitor for heaven’s sake is in the breath zone! AND ON THE VERY OUTSIDE OF YOUR CLOTHES!



Equipping workers with personal gas detectors is similar to equipping cars with seatbelts: they can only protect workers if they are used properly and consistently. A recent toxic gas fatality in Canada illustrates that buying gas detectors for workers does not automatically ensure worker safety. In order to protect workers, the instruments have to be used correctly. A critical part of safety programs that include use of gas detectors are the procedures used to verify that the instruments are being used properly. Failure to surveil and enforce proper use of gas detectors that had been issued to workers was one of the root causes of the Canadian accident. The accident occurred at an oil-drilling site characterized by the potential presence of hydrogen sulfide. 

Hydrogen Sulfide (HS) - A flammable, toxic, colorless and corrosive sulfur based gas recognizable by its rotten egg odor. Detection by odor is unreliable since it rapidly deadens the sense of smell.  Recognized exposure limits are:
 OSHA Acceptable Ceiling Concentration: 20 ppm

 Threshold Limit Value (TLV): 10 ppm
 Short Term Exposure Limit (STEL): 15 ppm

Hydrogen sulfide (H2S) is a colorless gas that at low concentrations famously has an odor similar to rotten eggs. At higher concentrations, H2S rapidly deadens the sense of smell. For most persons, a concentration of 150 PPM is enough to immediately deaden the sense of smell. At air concentrations of about 750 PPM, inhalation of hydrogen sulfide gas can cause immediate collapse and unconsciousness. If exposure is very brief, for example, transitory envelopment by a passing gas cloud, the victim may awaken promptly and experience no adverse effects at all. In industries where hydrogen sulfide exposure is commonplace, for example oil field work, employees often refer to this phenomenon as “knockdown”. A single breath at a concentration of 1,000 PPM results in immediate loss of consciousness, followed by cardiac arrest and death unless the unconscious individual is successfully revived. Because of the poor warning properties, extreme toxicity, and pervasiveness of this hazard, at many oil production sites and refineries every worker is required to wear a personal gas detector for H2S at all times while they are on site. Wearing an H2S “Clip” or “Badge” at these facilities is as routine as wearing a hardhat and eye protection. 


Personal Hydrogen Sulfide (HS) Monitor -

 A sensor worn within 18 inches of the nose on the outside of the clothing equipped with a visual read out and audible and vibration alarms that continuously measures HS levels in the air space around the wearer.  The initial alarm of these monitors is activated at 10 ppm and a second alarm activated at 15 ppm. OSHA  defines the breathing zone as the area “within a 10-inch radius of the worker’s nose and mouth.”   That would indicate that an instrument used primarily for personal protection from toxic hazards such as H2S should be worn on the collar, the lapel, on a breast pocket or even on the brim of a hard hat – or simply within a 10-inch radius of your nose and mouth.

Some would suggest that because gases like H2S are heavier than air that the instrument used to protect against them should be worn  lower on the body, around the knees or attached to the top of the boot.  While there may be some validity to this argument, I believe that this puts the instrument itself in danger of being damaged in the working environment or even lost without notice and may make it more difficult to recognize that the instrument is alarming in high noise areas.   

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