Confined Spaces – Part 1 An Overview of the Confined Spaces Issues Dr H D Wickramatillake

Confined Spaces Overview Part 1 of this overview will cover the following: How to identify a confined space, Confined space hazards, How to control or eliminate the hazards.

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:

Identifying a Confined Space 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 Confined Spaces Examples of confined spaces Tanks Manholes & Sewers Grain storage bins Boilers Other examples include vaults, pipelines, tank cars, and ship holds

Hazards of Confined Spaces Basic Principles For a description of an actual confined space fatality, click here.click here Confined spaces can be deadly. Some confined spaces are more hazardous than others. Confined space conditions can change rapidly from no hazards to life-threatening hazards. Some confined spaces are so hazardous, a written permit system is required for entry. The hazards of confined spaces can often be controlled or eliminated before entering.

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.

Hazard Identification 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 Air 100% Methane 100% Air 0% Methane 0% 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 % OxygenSymptoms 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, death Using an “inerting gas” like nitrogen, to counteract flammable vapors will result in an oxygen deficiency.

Hazard Identification A word about oxygen-enriched atmospheres A confined space with oxygen amount above 23.5% is considered “oxygen-enriched”. The source of extra oxygen is typically from leaking oxygen cylinders used for oxy-acetylene torches. Oxygen above 23.5% is a fire or explosion hazard. Green tanks contain oxygen

Hazard Identification Hazardous Atmospheres – Toxic Chemicals At very high levels, most chemicals in the air can be immediately life- threatening or cause permanent bodily harm. Most chemicals have “permissible exposure limits” (PELs) which will cause harm if exceeded. Even non-toxic or low-toxic chemicals can replace oxygen if levels are high enough. At lower levels, chemicals in the air can still cause harm.

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 (H 2 S) 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. H 2 S in parts per million (ppm) Death in minutes Smell 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, click hereclick here

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: See Part 2 for more information on a written permit system.Part 2

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.

Hazard Control Hazardous Atmospheres Dangers It is difficult to eliminate hazardous atmospheres in most sewers lines. Tank sludge or sewer sludge can release toxic gases during cleanup. Toxic or flammable gases can exist in pockets or layers.

Hazard Elimination How To Eliminate Physical Hazards Lock-out moving parts De-energize electrical parts or wiring Blank or block steam pipes and product in-feeding pipes.

If Hazards Can’t Be Eliminated If hazards cannot be completely eliminated, there are only two options: a complete written permit system, or “alternate procedures.” Both require training of employees. See Part 2 for more information on entry procedures.Part 2

Additional Information More information is available on WISHA webpage This presentation is just an overview and does not cover all requirements. For more information on how to put together a confined space program for your workplace, go to: For additional assistance, you can call one of our consultants. Click below for local L & I office locations:

Confined Space Quiz Question 1 Which of following are considered confined spaces? a)A sewer manhole b)A sub-basement vault with only one door c)A 20 foot deep ditch d)A 30-gallon drum

Confined Spaces Quiz Question 2 When can a hazardous atmospheres be fatal? a)When there is not enough air b)When there is 2% methane c)When there is 10% oxygen d)When there is no ventilation

Confined Spaces Quiz Question 3 Which of the following is not a good way to control hazardous atmospheres? a)Ventilate for two hours before entering b)Drain or pump out liquid contents c)Air test and ventilate continuously d)Remove any sludge from outside the space