{"success":true,"version":"v1","request":{"tool":"get_calculator_schema","calculator_id":"oxygen-tank-duration"},"result":{"entity_type":"calculator","id":"oxygen-tank-duration","calculator_id":"oxygen-tank-duration","canonical_url":"https://tttkmbb.com/medical/oxygen-tank-duration","name":"Oxygen Tank Duration Calculator","title":"Oxygen Cylinder Duration Calculator – Minutes Remaining from Gauge Pressure, Cylinder Size and Flow","category":"medical","category_name":"Medical & Clinical","tool_name":"estimate_oxygen_tank_duration","featured_mcp_tool":false,"description":"Estimates how long a compressed-gas oxygen cylinder will last from its gauge pressure, size-specific conversion factor (litres per psi), a safe residual pressure and the flow rate.","use_when":"You need to plan transport or home oxygen supply from a D, E, M, G or H/K cylinder at a continuous flow.","do_not_use_when":"The device is a liquid-oxygen reservoir or concentrator, or the flow is pulse-dose (conserving device), where duration depends on breath rate rather than continuous flow.","inputs":[{"name":"cylinder_size","label":"Cylinder size","type":"enum","required":true,"values":[{"value":"d","label":"D (0.16 L/psi, ≈ 350 L full)"},{"value":"e","label":"E (0.28 L/psi, ≈ 625 L full)"},{"value":"m","label":"M (1.56 L/psi, ≈ 3,450 L full)"},{"value":"g","label":"G (2.41 L/psi, ≈ 5,300 L full)"},{"value":"h_k","label":"H or K (3.14 L/psi, ≈ 6,900 L full)","aliases":["h","k","h/k"]}],"description":"US cylinder size letter; sets the conversion factor in litres of gas per psi.","example":"e"},{"name":"pressure_psi","label":"Gauge pressure","type":"number","unit":"psi","required":true,"min":0,"max":3000,"description":"Current cylinder gauge pressure (bar × 14.5).","example":2000},{"name":"flow_l_per_min","label":"Flow rate","type":"number","unit":"L/min","required":true,"max":60,"exclusive_min":0,"description":"Continuous oxygen flow.","example":2},{"name":"safe_residual_psi","label":"Safe residual pressure","type":"number","unit":"psi","required":false,"default":200,"min":0,"max":1000,"description":"Pressure reserved so the cylinder is never emptied (commonly 200 psi; 500 psi in some services).","example":200}],"outputs":[{"name":"cylinder_factor_l_per_psi","label":"Cylinder factor","type":"number","unit":"L/psi","decimals":2,"description":"Litres of gas released per psi for this cylinder."},{"name":"usable_oxygen_liters","label":"Usable oxygen","type":"number","unit":"L","decimals":0,"description":"(pressure − safe residual) × factor."},{"name":"duration_minutes","label":"Duration","type":"number","unit":"min","decimals":0,"description":"Usable litres / flow."},{"name":"duration_hours","label":"Duration","type":"number","unit":"h","decimals":2,"description":"Same duration in hours."},{"name":"duration_formatted","label":"Duration (h:mm)","type":"string","decimals":4,"description":"Hours and minutes."}],"input_schema":{"type":"object","properties":{"cylinder_size":{"description":"US cylinder size letter; sets the conversion factor in litres of gas per psi.","type":"string","enum":["d","e","m","g","h_k"],"examples":["e"]},"pressure_psi":{"description":"Current cylinder gauge pressure (bar × 14.5). Unit: psi.","type":"number","minimum":0,"maximum":3000,"examples":[2000],"x-unit":"psi"},"flow_l_per_min":{"description":"Continuous oxygen flow. Unit: L/min.","type":"number","maximum":60,"exclusiveMinimum":0,"examples":[2],"x-unit":"L/min"},"safe_residual_psi":{"description":"Pressure reserved so the cylinder is never emptied (commonly 200 psi; 500 psi in some services). Unit: psi.","type":"number","minimum":0,"maximum":1000,"default":200,"examples":[200],"x-unit":"psi"}},"additionalProperties":false,"required":["cylinder_size","pressure_psi","flow_l_per_min"]},"output_schema":{"type":"object","properties":{"cylinder_factor_l_per_psi":{"description":"Litres of gas released per psi for this cylinder. Unit: L/psi.","type":"number","x-unit":"L/psi"},"usable_oxygen_liters":{"description":"(pressure − safe residual) × factor. Unit: L.","type":"number","x-unit":"L"},"duration_minutes":{"description":"Usable litres / flow. Unit: min.","type":"number","x-unit":"min"},"duration_hours":{"description":"Same duration in hours. Unit: h.","type":"number","x-unit":"h"},"duration_formatted":{"description":"Hours and minutes.","type":"string"}}},"formula":"duration_minutes = (pressure_psi − safe_residual_psi) × cylinder_factor / flow_l_per_min; factors: D 0.16, E 0.28, M 1.56, G 2.41, H/K 3.14 L/psi","method":"Factors are the cylinder's full capacity divided by its service pressure (about 2,000–2,200 psi) and assume ideal-gas behaviour at room temperature; cold cylinders and regulator leaks shorten the real duration. Results are informational only and not a substitute for clinical judgement or medical advice.","sources":[{"name":"Hardavella G et al. (2019) Oxygen devices and delivery systems, Breathe 15:e108-e116","url":"https://pubmed.ncbi.nlm.nih.gov/31777573/","type":"peer_reviewed","retrieved_at":"2026-09-24"},{"name":"Respiratory Therapy Zone – Oxygen tank duration formula and cylinder factors","url":"https://www.respiratorytherapyzone.com/oxygen-tank-duration-calculator/","type":"reference","retrieved_at":"2026-09-24"}],"freshness":{"type":"static","max_age_seconds":null,"note":"Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output."},"examples":[{"name":"E cylinder, 2000 psi, 2 L/min, 200 psi reserve","inputs":{"cylinder_size":"e","pressure_psi":2000,"flow_l_per_min":2,"safe_residual_psi":200},"expected":{"usable_oxygen_liters":504,"duration_minutes":252,"duration_hours":4.2,"duration_formatted":"4 h 12 min"},"url":"https://tttkmbb.com/api/v1/calculate/oxygen-tank-duration?cylinder_size=e&pressure_psi=2000&flow_l_per_min=2&safe_residual_psi=200"},{"name":"D cylinder, 1500 psi, 4 L/min","inputs":{"cylinder_size":"d","pressure_psi":1500,"flow_l_per_min":4},"expected":{"cylinder_factor_l_per_psi":0.16,"usable_oxygen_liters":208,"duration_minutes":52},"url":"https://tttkmbb.com/api/v1/calculate/oxygen-tank-duration?cylinder_size=d&pressure_psi=1500&flow_l_per_min=4"}],"faq":[{"q":"Why subtract a safe residual?","a":"Regulators become unreliable near empty and a cylinder must never run dry during transport; 200 psi is a common reserve, some protocols use 500 psi."},{"q":"What about pulse-dose conservers?","a":"They deliver oxygen only on inspiration and typically extend duration 2–4 times; the manufacturer's conserving ratio is needed to convert."}],"tags":["oxygen tank duration","oxygen cylinder","e cylinder","psi","flow rate","oxygen supply"],"related":[{"calculator_id":"iv-drip-rate","reason":"Another time-and-flow calculation for clinical supplies."},{"calculator_id":"pressure","reason":"Convert cylinder pressure between psi and bar."}],"links":{"html":"https://tttkmbb.com/medical/oxygen-tank-duration","markdown":"https://tttkmbb.com/medical/oxygen-tank-duration.md","json":"https://tttkmbb.com/medical/oxygen-tank-duration.json","api":"https://tttkmbb.com/api/v1/calculate/oxygen-tank-duration","schema":"https://tttkmbb.com/api/v1/calculators/oxygen-tank-duration","openapi":"https://tttkmbb.com/openapi.json","mcp":"https://tttkmbb.com/mcp"},"version":"v1","updated_at":"2026-09-24"},"timestamp":"2026-09-24T01:50:26Z","next_actions":[{"tool":"run_calculator","calculator_id":"oxygen-tank-duration","reason":"Run Oxygen Tank Duration Calculator with the inputs above."}],"links":{"markdown":"https://tttkmbb.com/medical/oxygen-tank-duration.md"}}