What is a Confined Space? Is large enough and so configured that an employee can enter bodily and perform work; Has limited or restricted means of entry or exit; Is not designed for continuous human occupancy. Examples of Confined Spaces: Tanks Manholes Boilers Furnaces Sewers Silos Hoppers Vaults Pipes Trenches Tunnels Ducts Bins Pits Potential Hazards in Confined Spaces Oxygen Deficiency 23.5% oxygen concentration Combustibles Methane Hydrogen Acetylene Propane Gasoline fumes Toxic Materials Carbon Monoxide Hydrogen Sulfide Welding fumes Corrosives Electricity Mechanical Hazards Mixers Crushers Hazards of Confined Spaces Oxygen Deficient Atmospheres Oxygen Enriched Atmospheres Flammable Atmospheres Toxic Atmospheres Temperature Extremes Engulfment Hazards Noise, Slick/Wet Surfaces, Falling Objects Oxygen Deficient Atmospheres 19.5 % Minimum acceptable oxygen level. 15 - 19% Decreased ability to work strenuously. Impair coordination. Early symptoms. 12-14% Respiration increases. Poor judgment. 10-12% Respiration increases. Lips blue. 8-10% Mental failure. Fainting. Nausea Unconsciousness. Vomiting. 6-8% 8 minutes - fatal, 6 minutes - 50% fatal 4-5 minutes - possible recovery. 4-6% Coma in 40 seconds. Death Oxygen Enriched Atmospheres Oxygen level above 21%. Causes flammable and combustible materials to burn violently when ignited. Hair, clothing, materials, etc. Oil soaked clothing and materials. Never use pure oxygen to ventilate. Never store or place compressed tanks in a confined space. Flammable Atmospheres 2 Critical Factors: Oxygen content in the air. Presence of a flammable gas, or vapor Presence of dust (visibility of 5’ or less) Proper air/gas mixture can lead to explosion Typical Ignition Sources: Sparking or electric tool. Welding / cutting operations. Smoking Toxic Atmospheres Product stored in a confined space: Gases released when cleaning. Materials absorbed into walls of confined space. Decomposition of materials in the confined space. Work performed in a confined space: Welding, cutting, brazing, soldering. Painting, scraping, sanding, degreasing. Sealing, bonding, melting. Areas adjacent to a confined space. Hydrogen Sulfide Decomposition of materials. Human waste. Rotten egg odor at low concentrations. Possibly no warning at high concentrations. PPM Effect Time 10 ppm Permissible Exposure Level 8 Hours 50 - 100 Mild Irritation - eyes, throat 1 Hour 200 - 300 Significant Irritation 1 Hour 500 -700 Unconsciousness, Death 1/2 - 1 Hour >1000 Unconsciousness, Death Minutes Temperature Extremes Extremely hot or cold temperatures. Steam cleaning of confined spaces. Humidity factors. Extremely cold liquids. Work processes inside the confined space can increase temperature extremes. Personal protective equipment. Engulfment Hazards Loose, granular materials stored in bins and hoppers - grain, sand, coal, etc. Crusting and bridging below a worker. Flooding of confined space. Water or sewage flow. Other Hazards Noise Amplified due to acoustics within the space. Damaged hearing, affect communication. Slick / Wet Surfaces Slips and falls. Increased chance of electric shock. Falling Objects Topside openings expose workers inside confined space to falling objects. Testing The Atmosphere Verify presence of safe work atmosphere. Test all areas of a confined space. Top, Middle, Bottom Methane is lighter than air. Carbon Monoxide is the same as air. Hydrogen Sulfide is heavier than air. Oxygen Deficiency. Test the Atmosphere Check for Oxygen Content: At least 19.5% and less than 23.5% Check for Combustibles: Less than 10% of the LEL Check for Toxic Gasses: Most commonly carbon monoxide (PEL
Posted on: Fri, 12 Sep 2014 17:28:06 +0000
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