Page 12 - Confined Space Training - Student Manual 2021

This is not a comprehensive list of contributing factors. One must recognize that workers,
regardless of position, constantly make decisions on how a job will be done. These decisions, if
flawed, could result injury or death.

The message: Make the right decisions, those that could save your life or the lives of
others.

Therefore, consider that the most unfavorable situation exists in every entry process and that the
danger of explosion, toxic exposure, and asphyxiation could be present, until proven otherwise.

Hazards Specific to Confined Spaces Could Result From:

1. The material stored or used in the confined space: As an example, damp activated
carbon in a filtration tank will absorb oxygen, thus creating an oxygen deficient atmosphere.

2. The activity carried out: Such as the fermentation of molasses which creates ethyl
alcohol vapors and decreases the oxygen content of the atmosphere.

3. The external environment: As in the case of sewer systems which may be affected by
high tides, heavier than air gases, or flash floods.

4. Decomposing organic material inside the confined space: Organic material that has
decomposed tends to produce decomposition products that could be dangerous to
humans. Decomposition products could include methane, carbon monoxide and hydrogen
sulfide gas.

5. Rusting metal parts located in the confined space: Rusting is an oxidation process
that consumes oxygen. Consequently, heavy rust within a confined space could signal
that an oxygen deficient atmosphere exists with the space.

6. Welding and cutting operations: Hot work can quickly reduce oxygen concentrations to
unhealthful levels because the hot work uses up oxygen in the space.

Storyline: The dangers of not evaluating all the internal confined space hazards.

A laborer drowned in a bin being overcome by toxic vapors. He was attempting to clean the
sealant, glue, and adhesive residues from the bin walls with a high-pressure steam hose.
Trichloroethane was a major component of the residue mixture. He apparently was overcome by
the released solvent vapors and fell into the accumulated water at the bin bottom. The bin
eventually overflowed before he was discovered.

All the hazards of open top and limited access confined spaces may be present together with the
additional hazard of moving parts. Digester and boilers usually contain power-driven equipment
that, unless properly isolate, may be inadvertently activated after entry. Such equipment may also
contain physical hazards that further complicate the work environment spaces can be divided into
four distinct categories:
FLAMMABLE TOXIC
IRRITANT/CORROSIVE ASPHYXIATING

Confined Space Training for Entrants, Attendants & Supervisors 12