In the context of breathing apparatus, "demand type" refers specifically to the mechanism by which air is supplied to the user. In this system, air is delivered only when the user inhales. The inhalation creates a negative pressure that triggers the supply of air, thus allowing the user to breathe in oxygen-rich air as needed. This demand-based operation is efficient because it conserves air, ensuring that it is only released during inhalation, reducing the likelihood of waste.
This design is particularly beneficial in scenarios where the wearer may need to extend their air supply, as it limits unnecessary air flow when the user is exhaling or not breathing in deeply. The demand type apparatus is generally lighter and more comfortable for the user compared to systems that provide a continuous air supply, which can be bulkier and may lead to faster depletion of air.
Understanding the mechanics of demand-type systems allows users to better appreciate their applications, advantages, and operational requirements in various environments—including confined spaces or hazardous areas where the inhalation of harmful substances must be avoided.