5 Confined Spaces

21
Confined Spaces

Transcript of 5 Confined Spaces

Page 1: 5 Confined Spaces

Confined Spaces

Page 2: 5 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:

Page 3: 5 Confined Spaces

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

Page 4: 5 Confined Spaces

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

Page 5: 5 Confined Spaces

Hazards of Confined Spaces

What are the main hazards of confined spaces?

• Hazardous atmospheres

• Engulfing materials

• Entrapment

• Moving parts

• Electricity

Page 6: 5 Confined Spaces

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.

Page 7: 5 Confined Spaces

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.

Page 8: 5 Confined Spaces

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

Page 9: 5 Confined Spaces

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

Page 10: 5 Confined Spaces

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

Page 11: 5 Confined Spaces

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

Page 12: 5 Confined Spaces

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

Page 13: 5 Confined Spaces

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

Page 14: 5 Confined Spaces

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

Page 15: 5 Confined Spaces

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

Page 16: 5 Confined Spaces

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.

Page 17: 5 Confined Spaces

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

Page 18: 5 Confined Spaces

Hazard Identification

Other Recognized Hazards

Electrical lines, steam lines or hydraulic lines

Mechanical hazards (moving parts)

Hazards caused by the work(welding, painting etc.)

Page 19: 5 Confined Spaces

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:

Page 20: 5 Confined Spaces

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.

Page 21: 5 Confined Spaces

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.