A hоme cаre pаtient cаlls the DME cоmpany fоr which you are employed and reports her oxygen concentrator has stopped working. You instruct her to switch over to her H-cylinder backup system until you are able to go make a home visit and check the oxygen concentrator. You ask the patient to read the pressure gauge so that you know how much time you have until the H-cylinder will be empty. It is reported the H cylinder reads 2000 psig and the patient uses 2.5 L/min/NC continuously. How long will the cylinder last?