The Firesafe Cannula Valve and Firesafe Nozzle have been carefully designed to minimise resistance to the flow of oxygen.
Considering the worst case – an oxygen concentrator with a non-backpressure compensated flowmeter calibrated at atmospheric pressure. If two Firesafe valves were installed in series, at an oxygen flow of 5 l/min, the actual oxygen flow would be around 5.05 l/min when the flow indicator reads 5.00 l/min.