Assertion: oxygen's pressure | /r/CapableOf | remain constant
Facets:
value: to provide a reliably predictable mixture
type: PURPOSE
Source sentences:
text: The mass flow through a sonic orifice is a function of the upstream pressure and the gas mixture, so the upstream pressure must remain constant for the working depth range of the rebreather to provide a reliably predictable mixture in the breathing circuit, and a modified regulator is used which is not affected by changes in ambient pressure.