Definition - What does demand respirator mean?
A demand respirator is a type of negative-pressure face-piece which supplies breathable air from a source of oxygen to the wearer. This type of respirator is used in environments that are too contaminated for the wearer to breathe in the atmosphere, even with filtration. This can be due to the atmosphere either being oxygen-deficient or too contaminated for it to be purified through a respirator before inhalation.
SureHire explains demand respirator
In workplace environments where workers are exposed to contaminated air filled with toxic gases, low oxygen-concentration, or the air temperature is too high or too low, the employer is required by The National Institute for Occupational Safety and Health (NIOSH) to protect workers by supplying the correct respirator for the environment the worker is exposed to. A demand respirator works by creating a negative pressure within the face-piece on inhalation which results in the flow of oxygen though the admission valve of the oxygen source to the wearer.