Confined Spaces – Part 2 An Overview of the WISHA Confined Spaces Standard.
5 Confined Spaces
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Transcript of 5 Confined Spaces
Confined Spaces
Identifying a Confined Space
What is a confined space?
is large enough to get whole body inside,
is not designed for human occupation,
has limited or restricted entrance or exit.
It must have all three characteristics to be a confined space.
A confined space is an enclosed space that:
What is limited or restricted entry or exit?
The ability to easily escape in an emergency is impeded by such obstacles as:
a manhole
a small door or opening
a ladder
a long tunnel
In most cases, a trench is not considered a confined space.
Restricted exit
Exit not restricted
Identifying a Confined Space
Examples of confined spaces
Tanks
Manholes & Sewers
Grain storage bins
Boilers
Other examples include vaults, pipelines, tank cars, and ship holds
Identifying a Confined Space
Hazards of Confined Spaces
What are the main hazards of confined spaces?
• Hazardous atmospheres
• Engulfing materials
• Entrapment
• Moving parts
• Electricity
Hazard of Confined Spaces
When is a confined space so dangerous a written entry permit system is required?
• When there is an actual or potential “hazardous atmosphere” or
• when the space contains loose material that can engulf a person, or
• when the space is configured in a way that can trap a person, or
• when there is any other recognized serious safety and health hazard.
Hazard Identification
A “hazardous atmosphere” in a confined space has one or more of the following:
Flammable gas, mist or vapor
Oxygen content below 19.5% or above 23.5%
Air contaminant concentrations that would cause death, incapacitation, or permanent
health problems
Flammable dusts
You must do air monitoring to determine if a hazardous atmosphere exists.
Hazardous Atmospheres – Flammable Gases, Vapors and Dusts
Flammable gases, vapors or dusts will ignite from a spark or flame if above a level in the air called the “lower flammable limit” (LFL).
Gas or vapor levels higher than 10% of the LFL are considered hazardous and the confined space cannot be entered until levels are reduced.
Amounts above 10% of the LFL are usually toxic as well.
LFL is sometimes called “LEL” – “lower explosive limit”
Hazard Identification
Air100%
Methane
100%
Air0%
Methane0%
Too Rich
5.3%LFL
15.0%UFL
Example of flammable gas levels - Methane
Boom!
An open flame or a spark will cause an explosion when methane
amount is between 5.3% and 15%, the upper flammable limit (UFL).
Too Lean
Hazard Identification
Hazardous Atmospheres – Oxygen Deficiency
A reduction in oxygen is caused by tank rusting, microbe activity, or replacement by another gas.
Lack of oxygen can cause a person to immediately collapse and die.
Normal air contains 21% oxygen. A space with oxygen content below 19.5 % is considered “oxygen deficient”.
21% 0%19.5%
Oxygen deficiency exists
Oxygen content
Hazard Identification
Effects of Oxygen Deficiency% Oxygen Symptoms
19.5% - 16% Fatigue, mild impaired coordination
16% - 12% Increased breathing rate and pulse; impaired coordination, perception or
judgment
12% - 10% Further increased breathing rate, blue lips, mental confusion
10% - 8% Fainting, nausea, vomiting, mental confusion within few minutes
8% - 6% Collapse, death within 8 minutes
6% - 0% Coma within 40 seconds, deathUsing an “inerting gas” like nitrogen, to counteract flammable vapors will result in an oxygen deficiency.
Hazard Identification
Hazardous Atmosphere – Toxic Chemicals
The most common toxic chemicals in confined spaces fatalities are hydrogen sulfide and carbon monoxide
Other toxic chemicals can include welding fumes, vapors from liquid residues in storage tanks, or chemical products used in the confined space.
Chemicals can quickly reach toxic levels in the air of a confined space, especially gases, solvent vapors or sprayed products.
Hazard Identification
Hazardous Atmospheres–Hydrogen Sulfide (H2S)
Hydrogen sulfide gas is commonly found in sewers.
It can be instantly fatal at higher levels in a confined space.
Disturbing sewage sludge can release more hydrogen sulfide gas.
H2S in parts per million (ppm)
30 200 2000100 1000
Death in minutesSmell
strong odor
Instant collapse
Coughing,red eyes
Loss of smell
600
Unconscious in 30 min.
Hazard Identification
Hazardous Atmospheres – Carbon Monoxide (CO)
Carbon monoxide comes from operating internal combustion engines in or near confined space.
Propane-powered engines also emit carbon monoxide.
Fatal levels of CO are quickly reached in confined spaces.
Propane-powered manlift in a large tank
The PEL for CO is 35 ppm. To see the effects of CO
Hazard Identification
The Importance of Air Monitoring
Air monitoring is required whenever there is a possibility of hazardous atmospheres.
Atmospheric conditions can change quickly in a confined space.
A portable gas monitor with an alarm should be used by the person entering the confined space and checked frequently.
Confined space gas monitor
Hazard Identification
What are the Hazards of Engulfing Material?
Engulfing materials include liquids or loose solids such as grain, sand or other granular material.
People cannot escape when caught in moving loose solids and usually suffocate.
Workers often get engulfed when in-feed or out-feed lines are inadvertently opened or activated.
Hazard Identification
What is Entrapment?
The space is configured in a way that can trap a worker, for example, sides sloping towards the center
Gravel hopper Sawdust Cyclone
Hazard Identification
Other Recognized Hazards
Electrical lines, steam lines or hydraulic lines
Mechanical hazards (moving parts)
Hazards caused by the work(welding, painting etc.)
Controlling the Space
• Prevent employee entry.
• Remove or reduce hazards in the space first, before a person enters.
• If hazard cannot be controlled, you must use a written permit system to enter safely.
The hazards of a confined space can be be controlled in the following ways:
Controlling the Space
Warning employees and controlling access
Limit employee access to confined spaces by using entry barriers or locks.
Post warning signs at the entrance of confined spaces.
Make sure that unauthorized workers do not enter the confined space.
Hazard Control
How To Control Hazardous Atmospheres
Drain or pump out liquid contents, if any.
Blank off all in-feeding lines.
Air test and ventilate.
Continue ventilating constantly.
If possible, remove any sludge from outside the confined space.
Exit space if conditions deteriorate.