Page 21 - Confined Space Training - Student Manual 2021

Tips and Techniques

when a space is ventilated by positive pressure, air is blown into the space by a blower. The
increased air pressure from the blower forces the contaminated atmosphere out and allows
uncontaminated atmosphere to enter.

Positively pressurizing a confined space by blowing clean air into the space is an effective
means of providing a healthful atmosphere. Mechanical ventilation is much more effective
than natural ventilation where air movement is created by breezes and temperature differences.

• Locating the duct of the mechanical blower in the confined space is important to effective
contaminant removal.
• Locate the duct low in the confined space. The objective is to create turbulence and mixing
to force contaminated air to move toward and out of the opening.
• Be alert for dead ends, machinery, or areas where it is difficult to create air movement.
• Open all possible openings to the space to assist with ventilation.
• Ventilation should be run for a period of time sufficient to have several air changes.
Different organizations may require air changes of from 6 to 10 before entry. Always
measure for contaminant levels before entry is attempted.
• Exercise care when setting up a forced-air system so that short-circuiting does not occur
(contaminated air coming out of the space is captured by the fan and forced to reenter the
space). Likewise, other contaminants in the vicinity, such as automobile exhaust could be
forced into the space.
• If possible, using push/pull ventilation is an effective and efficient method of ventilating a
confined space. In this method, two openings (remote from each other) are utilized for
ventilation. Place a blower in one opening to blow clean air into the space. Locate a second
blower at the second opening to suck air out of the space. The objective is to create a
curtain of fresh air moving from the inlet opening toward the discharge opening.

Cannot be used in a flammable area unless using a CLASS I or CLASS II blower.

• A permit required confined space cannot be changed to non-permit confined space due
to ventilation removing the hazard only.

CARBON MONOXIDE CAN BUILD UP IN OUR SYSTEM TO CREATE CHRONIC EXPOSURE
SYMPTOMS. ADDING TO THE LEVELS IN OUR WORK LIFE CAN CAUSE HEADACHE,
FATIGUE AND OTHER ISSUES.

Do you have a carbon monoxide detector in your home? Do you have a fireplace or natural gas
heater?

If yes, the importance to you is clear. Should it be so at work?

If no, is this something you would consider for the safety and health of yourself and/or your family?

Confined Space Training for Entrants, Attendants & Supervisors 21