Ventilation in a confined space is the continuous flow of fresh air into it by a mechanical means, achieving and maintaining acceptable and safe atmospheric levels. It must be continued while employees work in the space to maintain a safe oxygen level, provide protection in case chemicals are accidentally released, to remove contaminants that are created by the work being performed, or to cool down the confined space.
Ventilation is created by displacing air and diluting it by introducing fresh, forced-air, or by continuously removing contaminants with exhaust ventilation at point sources. The points of air supply and exhaust should be separated as far as possible to ensure the most adequate ventilation. It’s important to remember that you should not use pure oxygen to ventilate a confined space. The air inside of the confined space should always be tested from outside of it prior to entry, and then throughout – side-to-side, and top to bottom.