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Confined Space EntryVentilation

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Confined Space Entry• Guiding Thought…

– If possible, develop a plan for how you will ventilate a confined space well before it is needed

– This may not always be possible

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Dow Requirements• The Global Confined Space Standard (ODMS

06.05.C.2) has specific requirements relating to Ventilation:

• The purpose of this presentation is to provide supporting guidance for personnel responsible for carrying out ventilation– If you are responsible for ensuring that a confined

space is effectively ventilated you must be trained and competent to do so

– If in doubt STOP before the confined space is entered and seek GUIDANCE

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Ventilation Overview

• Ventilation

–Ventilation Requirements

–Types of Ventilation

–Guidance on Using Ventilation

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Confined Space Entry Requirements Summary

• 02.02 Prior to any person entering a Confined Space:– C. Forced or induced ventilation shall be

provided, except in areas where it is not effective (for example: dikes, pits, trenches, open barges, confined spaces with open tops, etc).

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Confined Space Entry Requirements Summary

• 02.16: Ventilation shall be provided such that:a. The levels of airborne contaminants shall remain at or

below the levels (concentrations) determined during the initial entry permit conditions (initial hazard monitoring)

b. The oxygen level does not drop by more than 1% from the level determined during the initial entry permit conditions, and does not enter a range where different respiratory protection requirements are needed. At no time shall the oxygen level drop below 17%.

• 02.17: The exhaust from air movers powered by non-breathing air supplies (e.g., plant air) must discharge away from the Confined Space during entry

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Confined Space Entry Requirements Summary

• 02.18: Inert gas supplies (e.g., nitrogen) shall not be used to power air movers

• 02.19: Air movers must be electrically grounded by bonding them to the Confined Space. When using non-conductive Confined Spaces, the air movers will be bonded to the nearest source to ground.

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Confined Space Entry Requirements Summary

• 02.20: When work inside a confined space could introduce an airborne contaminant (welding, coating materials, painting, curing agents for a tank lining, etc.) then additional ventilation must be provided to prevent the level of introduced airborne contaminant from entering a range at which different respiratory protection is needed. If not possible, or if the introduced airborne contaminants is not known or can not be measured, then additional respiratory protection requirements must be determined.

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Ventilation Types• Positive Pressure

– Also called supply or dilution ventilation– Fan/blower used to push fresh air into space

forcing contaminants out– Effective method of ventilation for atmospheres

which are potentially oxygen-deficient– It requires less energy to push air into a space

than it does to pull it out of a space • (higher effectiveness if you push air into a space)

• Negative pressure– Also called exhaust or extraction ventilation – Fan or blower used to pull contaminants out – Effective ventilation requires contaminants to be

close to the inlet of the air mover or duct

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Ventilation Guidance

• Typical air-mover used for ventilation of a confined space– Blows air into space

• Note: This device is powered with air, NOT an inert gas such as nitrogen– In this case the

connection is specific to plant air

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Ventilation Guidance• In this example the air-

mover is positioned in the man-way of a vessel to remove air from inside the space

• Air-mover is placed to exhaust contaminated air away from confined space

• “elephant trunk” flexible ductwork can be positioned anywhere inside of vessel– useful for welding where

local exhaust ventilation may be needed

• Grounding strap

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Ventilation Guidance

1. The air moving into the confined space is not contaminated and contains the required amount of oxygen

2. The contaminated air exhausted from the confined space does not cause a build up of harmful materials in the workplace surrounding the vessel.

When using any ventilation device, it must be ensured that:

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Ventilation Summary• Adequate ventilation needs to be assessed for each

confined space entry• Below is some General Guidance that can be applied:

– Provide continuous exhaust ventilation when tasks conducted in a confined space may create an atmospheric hazard

• Welding, painting, disturbing sludge/product, curing agents, etc

– Confined spaces should have at least 2 openings• Best practice is to push air in one opening and pull air from the other

opening

– There must be good air mixing inside of the confined space to prevent the build up of stagnant air

• What will be the air path through the space? Are there dead spots?

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Ventilation Summary

• General Guidance…continued:– When possible, purge the confined space for at least

24 hours prior to entry– Position ventilation to blow contaminants away from

workers– Consider conditioning the air prior to putting it into the

space • especially for hot climate areas