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| Gas safety in confined spaces. | | | DR.MANZOOR AHMAD YETOO | 1/23/2014 9:48:04 PM |
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Gas Safety is an important aspect of staying safe at home, workplace, travelling etc.It becomes very important to know about safety precautions of gases especially confined spaces.We experience many causalities by gas Hazards in Jammu and Kashmir especially during winters where we fail to follow safety precautions in confined spaces. Fatalities in confined spaces happen quickly in seemingly innocuous situations. Inhaling an atmosphere that contains no oxygen causes loss of consciousness in a matter of seconds because such an atmosphere not only fails to provide fresh oxygen but also removes oxygen already present in the bloodstream.
When an oxygen-free atmosphere is breathed, the breathing process is reversed and instead of carbon dioxide, it is oxygen which diffuses from the blood in the lungs to the inhaled air.
My purpose of this article is to aware the masses about the risks and precautions in confined spaces so that precious lives are not lost by ignorance and due to lack of safety culture at home as well as at work places. A Confined Space is any space large enough for someone to enter and perform assigned work, which has limited means of entry or exit, and which is not designed for continuous worker occupancy. There are many industry sectors that carry out work involving confined spaces. The US Occupational Safety and Health Authority (OSHA) estimates that 2 million workers annually enter confined spaces in some 225,000 workplaces. If we translate this statistic globally, it is clear that tens of millions of workers enter confined spaces every year. The implications are clear – confined spaces are a universal problem for industry as well as for house holds. This covers just about every industry, including utilities, construction, hydrocarbon exploration and processing, petrochemicals, marine, agriculture, food processing and brewing, airlines, houses, as well as the emergency services. In residential dwellings, improvements to home insulation and the push to make older homes more energy efficient have resulted in many homes becoming more airtight. The reduced fresh air exchange has made the dangers of CO more prevalent. In recent years, there have been provincial requirements to install CO detection in dwellings that have wood burning appliances, such as a fireplace Gas burners ,LPG burners etc. Today, increased public awareness of the dangers of CO has resulted in a legal push in many municipalities and other regulating bodies, towards the required installation of detectors in all homes, regardless of the appliances they may have. In a home there may be low amounts of CO generated by the furnace, water heater, stove, etc. on a constant basis. The levels should not rise to dangerous levels under normal operating conditions. As such, the purpose of a detector is to alert of a dangerous situation, which requires evacuation and further human intervention to alleviate the problem source. In the ventilation market however, a different rationale and approach applies. Carbon Monoxide in parking structures, loading bays, and service facilities can become a serious issue if not controlled through adequate ventilation. In these places, the concern is not whether CO may reach unsafe levels but rather how to control and ventilate the CO when it does rise above safe levels. In these cases, high levels of CO are generated from vehicles on a regular basis by the nature and use of the facility. Since the general public and workers use these facilities, a new set of rules applies. The Ontario Ministry of Labour provides guidelines of exposure to hazards when workplace safety is considered. Typically, allowable exposures to CO are adopted from the ACGIH (American Conference of Governmental Industrial Hygienists). These are updated annually by the ACGIH and routinely updated within the regulating bodies of Ontario.. The new guideline may consider adopting 25 ppm CO on a time-weighted average over the course of a normal 40-hour workweek. Previously this was set at 35 ppm CO. Employers must assess the risks these workplaces pose to their employees and Endeavour to prevent them so should be the approach of general public at their respective homes In most cases, both the assessment and the safe working system will require testing of the atmosphere with gas detection equipment.
Confined space gas risks can be divided into three broad categories: combustible gas, toxic gas, and oxygen depletion or enrichment.
Combustible gas risks
For combustion to occur the air must contain a minimum concentration of combustible gas or vapour. This quantity is called the lower explosive limit (LEL). Different compounds have different LELs so it’s vital that detectors are capable of detecting at the correct levels.
Typically, storage vessels which have contained hydrocarbon fuels and oils present a danger. Other dangers come from fuel leaks: burst fuel containers; pipelines on and off site, gas cylinders and engine-driven plant. For workers in pits, sewers and other sub-surface locations, methane formed by decaying organic matter is an almost universal danger.
Toxic gases and vapours
Confined-space workers may be exposed to many toxic compounds, depending on the nature of the work. A risk assessment should be made of which toxic substances a worker may be exposed to in any given work situation.
When looking at toxic gases related to specific applications, the water industry for example uses many toxic compounds for cleaning and processing both waste and clean water. Hazards such as chlorine, ozone, sulphur dioxide and chlorine dioxide then pose additional risks both in storage and treatment areas.
Oxygen – too high or too low?
The normal concentration of oxygen in fresh air is 20.9%. An atmosphere is hazardous if the concentration drops below 19.5% or goes above 23.5%.
Precautions
Without adequate ventilation, the simple act of breathing will cause oxygen levels to fall surprisingly quickly. Combustion also uses up oxygen, so engine-driven plant and naked flames such as welding torches are potential hazards. Oxygen can also be displaced. Nitrogen, for example, when used to purge hydrocarbon storage vessels prior to re-use, drives oxygen out of the container and leaves it highly dangerous until thoroughly ventilated.
High oxygen levels are also dangerous. As with too little, too much will impair the victim’s ability to think clearly and act sensibly. Moreover, oxygen-enriched atmospheres represent a severe fire hazard. Best remedy includes monitoring of gas levels at regular intervals.
Both portable and fixed gas detectors can be used for confined space monitoring. Fixed systems typically comprise one or more detector “heads” connected to a separate control panel. If a detector reads a dangerous gas level, the panel raises the alarm by triggering external sirens and beacons. This sort of installation is suited to larger spaces like plant rooms, which have sufficient room for the hardware or remote stations that are usually unmanned.
However, much confined space work takes place in more restricted areas, making compact portable units more suitable. Ease of use, with one button operation, means minimal training is required while increased safety is ensured. Combining one or more sensors with powerful audible and visual signals to warn when pre-set gas levels are reached, portable detectors can be carried or worn wherever they are needed. In addition, a compact instrument is easily carried in a confined space, ensuring that pockets of high gas concentration are not missed.
Certain features should be expected in every portable gas detector. Clearly, life-saving tools for demanding environments must be as tough as possible, with reliable electronics housed in impact-resistant casings. While the need to leave gas sensors exposed to the atmosphere means that no instrument can be fully sealed, a high degree of protection against dust and water ingress is essential. Toughness notwithstanding, a well-designed detector will also be light and compact enough to wear for an entire shift.
Because of the difficulties of working in a cramped space, perhaps under poor lighting, instruments should be easy to use. No matter how advanced a detector’s internal architecture or data management options, personnel in the field should be faced with nothing more daunting than a clear display, simple, one-button operation and loud/bright alarms. Finally a traditional approach of burning fuels that can generate carbon monoxide, carbon dioxide and other toxic gases should be avoided at the first place or reduced to safe limits by using safe practices.
[The author is an expert&auditor in occupational safety,Food safety,biomedical, environment and carbon trading, climate change certified i from USA and UK AND IRCA(international register for certified auditors)}
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