ABSTRACT
Recognizing that there is virtually an infinite variety of spaces and correspondingly infinite ways to ventilate them, this chapter describes some basic ventilation principles and concepts that may be applied to all spaces. The goal of confined space ventilation is to provide an atmosphere in which entrants can work safely. Natural ventilation uses the forces of nature to move air in and out of the space. The energy required for this movement is provided entirely by air currents, breezes, thermal gradients, and pressure differences which exist in and around the space. Local exhaust systems are used to capture contaminants at their source. The chapter points out that since every confined space is unique, it is impossible to provide a single set of ventilation guidelines that will apply in all situations. While atmospheric testing may be used to verify the adequacy of ventilation, it should not be relied on to determine if purging or ventilation is necessary.
