Reference — Transport Respiratory Care
Transport Oxygen Cylinder Duration Reference
The numbers behind transport oxygen planning in one place: the cylinder factor for each size, the duration formula, the safe residual you never breach, and an E-cylinder duration table across common flows.
Written by Apex Respiratory Editorial Team
Educational use only. This material supports respiratory therapy education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional protocols, or physician orders. Always follow facility policies and current provider orders, and verify calculations independently before clinical use.
Overview
Cylinder duration is the time a cylinder can supply a given oxygen flow before reaching its safe residual pressure. It depends on the current gauge pressure, the cylinder size (expressed as a factor in liters per psig), and the flow. Always plan for the full round trip plus reserve, and add drive-gas consumption for pneumatically powered transport ventilators.
Cylinder Factors & Approximate Capacity
| Cylinder Size | Factor (L/psig) | Approx Full Capacity (~2,200 psig) |
|---|---|---|
| D | 0.16 | ~350 L |
| E | 0.28 | ~625 L |
| M | 1.56 | ~3,450 L |
| G | 2.41 | ~5,300 L |
| H / K | 3.14 | ~6,900 L |
Duration Formula
Duration (min) =
(gauge pressure psig − safe residual psig) × cylinder factor ÷ flow (L/min)
- Full cylinder: approximately 2,200 psig
- Safe residual: approximately 200 psig (never breach this)
- Usable pressure:2,200 − 200 = 2,000 psig
E-Cylinder Duration by Flow
Assumes a full E cylinder starting at 2,200 psig with a 200 psig safe residual, yielding 2,000 usable psig × 0.28 = 560 usable liters.
| Flow (L/min) | Approx Duration |
|---|---|
| 2 L/min | 280 min (4 h 40 min) |
| 6 L/min | 93 min (1 h 33 min) |
| 10 L/min | 56 min |
| 15 L/min | 37 min |
Clinical Notes
Safe residual. Never run a cylinder below approximately 200 psig. The residual prevents contamination and maintains a working reserve.
- Bring reserve. A common rule is roughly twice the calculated need, or a dedicated backup cylinder, to cover delays.
- Pneumatic transport ventilators.These consume O₂ as drive gas in addition to the patient’s minute ventilation; the cylinder lasts less time than flow alone predicts.
- Approximate capacities.Listed capacities are approximate (factor × ~2,200 psig) and vary slightly by manufacturer. The cylinder factor and the duration formula are what you compute with.
Related Resources
Sources
- Kacmarek RM, Stoller JK, Heuer AJ. Egan's Fundamentals of Respiratory Care. 12th ed. Elsevier; 2021. Medical gas therapy: storage and delivery.
- Cairo JM. Mosby's Respiratory Care Equipment. 11th ed. Elsevier; 2022. Medical gas cylinders and regulators.