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

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 manholea small door or openinga laddera 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 binsBoilers

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.

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 SpacesWhat are the main hazards of confined spaces?

• Hazardous atmospheres

• Engulfing materials

• Entrapment

• Moving parts

• Electricity

Hazard of Confined SpacesWhen 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 IdentificationHazardous 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 DeficiencyA 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 Symptoms19.5% - 16% Fatigue, mild impaired coordination16% - 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 minutes6% - 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 (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 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 tankThe PEL for CO is 35 ppm. To

see the effects of CO, click 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 IdentificationWhat 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.

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 DangersIt 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.

Additional Information

More information is available on WISHA webpageThis 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:http://www.lni.wa.gov/wisha/consultation/regional_consultants.htm

http://www.lni.wa.gov/wisha/rules/confinedspace/helpfultools.htm

Confined Space Quiz

Question 1

Which of following are considered confined spaces?

a) A sewer manholeb) A sub-basement vault with only one doorc) A 20 foot deep ditchd) A 30-gallon drum

Confined Spaces Quiz

Question 2

When can a hazardous atmospheres be fatal?

a) When there is not enough airb) When there is 2% methanec) When there is 10% oxygend) When there is no ventilation

Confined Spaces Quiz

Question 3Which of the following is not a good way to

control hazardous atmospheres?

a) Ventilate for two hours before enteringb) Drain or pump out liquid contentsc) Air test and ventilate continuouslyd) Remove any sludge from outside the space