Oxygen Deficiency: The Silent Killer
By Ardem Antabian, Product Line Manager
Injury or death due to oxygen deficiency is a common hazard in many chemical, refinery and other industries. Toxic gas is often to blame when workers die unnecessarily due to asphyxiation in environments where the oxygen is actually depleted by gases such as nitrogen. To prevent these accidents, OSHA, NIOSH and other federal/state agencies have implemented numerous regulations, required procedures, permit processes -- as well as providing extensive preventative educational literature and announcing major enforcement actions.
OSHA investigations into worker deaths caused by oxygen deficiency or toxic gas almost always reveal a failure to install safety systems or utilize personal protective equipment and to follow the proper safety procedures -- especially in confined spaces. Today’s fixed oxygen-deficiency and toxic gas monitoring systems are highly reliable, relatively easy to install and operate, and offer simple maintenance. They provide excellent protection for employees and plant equipment.
Failing to provide a safe work environment can be costly -- in more than dollars and cents terms. First, there is a tragic loss of life that includes employees who are the primary victims as well as would-be rescuers, which often includes management. Then there is the cost of the investigation, corrective action, regulatory fines as well as major liability lawsuits that can completely drain a company -- both financially and in terms of staff business focus.
Human beings normally breathe air that is 20.9 percent oxygen by volume under normal atmospheric pressure conditions. When the concentration of oxygen decreases even slightly by a little more than 1-2 percent, people immediately begin to feel the effects. Healthy individuals are unable to work strenuously and their coordination may be affected in oxygen environments of 15-19 percent; those with coronary, pulmonary, or circulatory disease may feel symptoms.
With the depletion of oxygen to a mix of only 10 to 12 percent, respiration increases, lips turn blue and judgment is impaired. Fainting and unconsciousness begin to occur at 8 to 10 percent oxygen. Death occurs in 8 minutes at 6 to 8 percent oxygen; recovery is possible after 4 to 5 minutes if oxygen is restored. These values are approximate and may vary greatly depending on an individual’s health, physical activity and the specific working environment that they encounter.
There are a variety of causes that lead to oxygen deficiency. Leaking materials from storage tanks, natural gas lines, process valves and more release gas that displaces oxygen in poorly ventilated areas or confined spaces. Decomposing organic matter, such as animal, human or plant waste, produces methane, carbon monoxide, carbon dioxide, and hydrogen sulfide that displace or consume oxygen. Even corrosion, such as rust, or fermentation or other forms of oxidation will consume oxygen and pose a hazard.
Oxygen deficiency often occurs in confined spaces, which are defined as being large enough and configured so that a person can bodily enter and perform assigned work. Confined spaces have restricted means for entry or exit, and they are not designed for continuous employee occupancy.
Some confined spaces are designated as “permit-required” areas. These areas have material with the potential for engulfment, are configured so an individual could be trapped or asphyxiated by inwardly converging walls. They have a floor that slopes or tapers to a smaller cross-section, or they may have any other recognized serious safety or health hazard.
Many confined spaces are easy to recognize, such as manholes, sewers, boilers, silos, vessels, vats, pipelines, tunnels, storage tanks, ship compartments and underground vaults. Other confined spaces are less obvious, including open-topped water and degreaser tanks, open pits and enclosures with bottom access. These confined spaces prohibit natural ventilation, are potential sources of gas generation and can prevent gases from escaping to cause a hazardous atmosphere.
Let’s face it: If a work area isn’t properly ventilated or hazardous materials are in use, then there is the serious potential for oxygen-deficient or toxic gas conditions that could harm your facility’s workers. Explosive and toxic gases, including hydrogen sulfide and carbon monoxide, combined with a lack of oxygen are the cause of most confined space accidents.
Heroic efforts by would-be rescuers who are overcome by oxygen deficiency or other toxic gases actually result in 60 percent of all fatalities. When an accident occurs, sound the alarm, get help and call the professionals. One accident victim is more than enough. Do not attempt a rescue without knowing the hazard, understanding the required response and using the proper safety equipment.
When working in confined spaces that may have oxygen deficient or toxic gas environments, there are specific government regulations that apply to protect workers. These include, but are not limited to, the following:
29 CFR 1910.146 - "Permit-required Confined Spaces": This section of the Code of Federal Regulations contains requirements for practices and procedures to protect employees in general industry from the hazards of entry into permit-required confined spaces.
CPL 2.100 - "Application of the Permit-Required Confined Spaces (PRCS) Standards, 29 CFR 1910.146": This Compliance Directive provides additional information and instruction for OSHA personnel for use in answering questions and to ensure uniform enforcement of 1910.146.
Part 1915 Subpart B - "Confined and Enclosed Spaces and Other Dangerous Atmospheres in Shipyard Employment": This Subpart of the Code of Federal Regulations applies to work in confined and enclosed spaces and other dangerous atmospheres in shipyard employment.
Simple Prevention Steps
You can prevent oxygen-deficiency, toxic or combustible gas and confined space accidents. There are many companies that specialize in assessing hazardous working environments -- even your insurance company is often willing to help. Suppliers of fixed safety monitoring systems and personal protective devices will generally share their years of experience with many companies just like your own.
TS4000 Oxygen Deficiency Detector
Our TS4000 Intelligent Toxic Gas Detector continuously monitors toxic gases in the ppm range or oxygen deficiency, delivering highly accurate detection and protection. The unit features one person calibration and can virtually self-calibrate by simply activating a magnetic switch and applying gas. It provides status indication and alarm outputs. The TS4000’s advanced communications allow its sensors to be remote mounted up to 2000 feet away for greater installation flexibility.
TS4000 Oxygen Deficiency Detector specifications.TS420 Oxygen Deficiency Detector
Designed to monitor hazardous environments, the TS420 Oxygen Deficiency detector continuously monitors for dangerous conditions. The TS420’s rugged electrochemical sensor detects oxygen deficiency in percent by volume. It features an LCD indicator that displays status, fault and calibration cues. Its 4-20mA analog output circuitry supports remote alarm and fault indication requirements.
TS420 Oxygen Deficiency Detector specifications...
TS400 Toxic Gas Detector
The TS400 Toxic Gas Detector Series is a compact, fixed toxic gas detector with electrochemical cell sensors that detect a wide range of gases. Two-wire loop power eliminates the need and cost of a separate power supply. A built-in LCD indicator provides for status, fault and calibration cues. The TS400 detects CO, NO, NO2, SO2, ClO2, H2S, HCl, O3 and HCN.
TS400 Toxic Gas Detector specifications...
Oxygen Deficiency Monitoring System
Our MC600 Multi-Channel Controller is designed to provide an advanced gas monitoring system that sounds the alarm when oxygen deficiency or toxic and combustible gases are a problem. One MC600 Controller can be hardwired to up to six of our gas detectors (including our TS-Series gas detectors) installed at strategic plant locations. It delivers a total solution -- high performance, reliability and safety at a low cost per point.
Learn more information on the MC600 Controller...
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