Definition - What does positive pressure respirator mean?
A positive pressure respirator (PPR) is a piece of personal protective equipment (PPE) that is worn by an individual to provide them with a safe supply of air when they are working in a contaminated environment. Positive pressure respirators may be equipped with a facepiece that fits tightly against the wearer's face or a loose-fitting hood or helmet. Each type of PPR maintains positive air pressure through the delivery of supplied air to the wearer. This air supply creates positive pressure within the breathing zone of the wearer preventing ambient air from entering even in the event of a leak.
SureHire explains positive pressure respirator
Positive pressure respirators can supply a continuous flow of air at a predetermined level or a demand-controlled stream of air. Pressure-demand respirators increase or decrease the level of air supplied to the wearer depending on the individual's breathing rate. Both the continuous airflow and demand-based airflow respirators provide protection against leaks through the use of positive air pressure. This protection results from the fact that the air pressure within the respirator is greater than the air pressure of the surrounding environment. This pressure imbalance causes air to be pushed out of the wearer's breathing zone in the event of a leak.
However, exposure may still occur in the event of leakage if the worker's breathing rate is very high--outpacing the respirator's airflow rate. Temperature changes can also affect the protective capacities of positive pressure respirators.