Confined Spaces Flashcards
Definition
Any space by design has limited openings for entry and exit.
unfavorable natural ventilation
can contain or produce dangerous air contaminants and one which is not intended for continuous occupancy
Examples
tanks, vaults or manholes
Permit required confined space
- has the potention to contain a hazardous atmosphere
- material that has the material for engulphing someone entering the space.
- has an internal configuration such that anyone entering could be trapped or asphyxited by walls that converge inwardly or a floor that slopes downward and tapers to a smaller cross section
noise radiation electrictiy
Examples
storage tanks pits vats electrical manholes vaults boilers pipelines trenches or excavations
entering a confined space
A review of the specific guidelines is vital only allow entry after - training and equipment appropriate ppe osha;s procedures put into effect - proper permit issues
OSHA
Procedures - OSHA CFR 29 1910.146
designed to make the space safe elimate hazards and to train in safe work practices
Preliminary Evaluation
performed prior to site entry
secondary is more detailed to further identify existing hazards to aidd in the selection of appropriate engineering controls and personal PPE for future site eactivities. The evaluation mus tinclude all suspected conditions that are immediately dangerous to life or health - (IDLH) or that may cause serious harm to employees (confined space entry, potentially explosive or flammabvle situation s, visible vapor clouds, etc.).
Permit Required Confined Space Entry
Storage tanks, process vessels, silos, vaults, storage bins, hoppers, ship compartments, exhaust ducts , sewers, tunnels, and boilers. A space does not have to be enclosed to be considered a permit-requiored confimed space. Pits, trenches and open topped vats also fit the OSHA description since they may have limited means of entry ane exit, and are not intended for habitation and could possess hazardous atmospheres.
OSHA has determined that individuals who enter permit-required condined spaces are at a significant risk of death or injusry. Therefore, all permit-required confined spaces are to be considered dangerous until proven otherwise.
Permit System
The permit system
The permit is a mandatory checklist
Employer must implement a afunctional permit program if a permit- confined space is on the premises. Before entry is authorized, the employer muyst document:
- Measures that have beenb implemented to prevent unauthorized entry.
Hazards that have been identified and evaluated before employee entry.
The means, procedures, and practices necessary for safe permit space entry operations and show these have been developed and jmplemented.
Entry Permit OSHA Guidelines
Municipality will develop entry permit
- permit space to be entered
q. the purpose of the entry - The date and the authorized duration of the entry permit
- The authorized entrants by name, or a means that will allow the attendant to determine quickly and accurately which authorized attendants are within the space
- The personnel, by name, servicng as attendants
- The individual, by name, sercing as entry supervisor, with a space for the signature or initials of the entry super visor who originally authorized entry.
Addl
the individual who authorizes the entry must sign the permit. This identifies the party responsible shyloyule any problem arise during entry. It is assumed that the affixing of ones signature to the permit will insure that hte permit process has bben taken seriously and that all protective measures are actually in place. Permits have a definite dureation of effect and are canceled when the entry is over. This will assure that tall entrants and their equipment have exited the space before the space is returned to its normal state. TS permit is also canceled with an emergency develops and/or an evacuation of the space is necessitated.
Entry permit time
kept for 1 year. Annual review showing how many entries for a 12 month period. If no entries during the year then no entries or report is required.
Personnel Responsibilities in a confined space work area
must be aware of the hazards 1. planning entry and exit procedures 2. rescue and training drills at intervals as determined necessary by the employer use of testing equipment for atmospheric monitoring lockout procedures ventilation duties of attendant and entrant safety equipment use
Testing and monitoring
Atmospheric monitoring.
The results of this testing will govern every phase of entry.
- oxygen depletion
- flammability
- toxicity
Monituring practices and instruments should gear toward these three central hazards
Hazards
3 major - oxygen deficiency less than - flammable is where oxygen is in the air - potentially explosive -
Toxic atmospheres
Substances
- product stored in the space
- work performed in the space
- toxic materials stored in areas adjacent to the space
Labeling and Posting
All warning signs shall be printed in english and language of others not able to read in english
- entrances must be posted
- emergency procedures
- phone numbers for response and rescuse teams must be posted in the immediate areas of the confined space.
Work Practices
EEs shall review the specific guidelines or standards for appropriate safe entry and emergency exit. These guidelines or standards must be compiled by the qualified person and be definitive on all the prossible hazards in tareas covered by such guidelines.
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Ventilation
one of the greatest hazards is the atmosphere. ventilation is needed when an idlh or nearly idlh atmosphere exists in confined psaces. IFLH means toxis gas levels are above osha;s permissable exposure level , a flammable gas’ concentration is greater than 10% of its lower explosice limit (LEL) or oygen concentration is less than 19.5 % or greater than 23.5 %
Ventilation is not limited to those situation . Very hot environments can be ventilated with cooler air. Atmospheres that contain toxic gases can be ventilated even though the conventratio nis still below PEL. Some sources say that ventilation is adequate when it exchanges the atmosphere in the space 30 times per hour with 12 changes made piror to entry.
Atmosphere
Can be altered in many ways
flammable vapors can be absorbed by using activated carbon
The most frequently used method of altering or replacing eh atomosphere is through ventilation . Specific techniques vary according to: - size and orientation of the space size of the exhaust opening - types of vapors to be removed - source of the replacement air
Regardless of the ventilation technique used , it replaces a contaminated atmosphere with one that is uncontaminated.
Ventilation
Typed used
- the effect of the contaminants vapor density
- Application of positive or negative pressure
Example
Vertical Tank with methane gas.
The greater the difference in vapor density, the faster natural ventilation witll take place. Natuarally, the reverse flow would occur if the atmosphere in teh container had a vapor density greater than one, the vapor density of air. Many of the gases that need to be ventilated are either present in faily low voncentrations or have vapor densities lose to one.
Forced Ventilation
Means that hte natural ventilation is not very effective. It involves a fan, air complressor or other maching.
There are 2 types of forced ventilation:
- Positive pressure ventilation
- Negative-pressure ventilation