The first test performed is the Rated Service Time Test and Positive
Pressure Test. This test determines if the SCBA unit at a flow of 40 liters
per minute and 24 breaths per minute will meet or exceed the rated or stated
service time of the SCBA unit. The test is completed once the positive
pressure inside the facepiece goes below 0 inches of water. The positive
pressure test is performed at the same time as the service time test. This
positive pressure test measure the facepiece positive pressure over the
duration of the test. This pressure must not go below 0 inches of water at
any time during the rated service time. The gas flow test measure the
maximum flow of the SCBA unit possible at a facepiece pressure of 0 inches
of water or greater. This flow is measured at full cylinder pressure and at
500 pounds per square inch gauge PSIG. The flow must be over 200 liters per
minute for both pressures.
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