Cylinder-duration math is a resource-management problem. The relationship combines usable pressure, the cylinder factor, and flow rate. The real performance skill is recognizing the same structure when the numbers are embedded in a transport scenario.
Cylinder factors, residual-pressure policies, device characteristics, and operational practices vary. Use the values specified by your program, service, equipment, or reference.
Before you move on, ask whether the unit, direction, and magnitude make sense. A correct-looking calculator result can still come from the wrong relationship.
Why reasonableness matters →Educational example: pressure 1800 psi, residual 200 psi, factor 0.28 L/psi, flow 10 L/min. What approximate duration does that relationship produce?
Use the animation to reveal the structure progressively. The goal is not speed yet—it is a clean sequence you can retrieve later.
Educational example: pressure 1500 psi, residual 200 psi, factor 0.28 L/psi, flow 8 L/min. What approximate duration does that relationship produce?
Reset the noise. You do not have to solve the whole problem at once. Name the unit you need: minutes.
Anchor the target. Not all displayed pressure is treated as usable in this example. Subtract the specified residual first.
Generate one correct move. One correct move: 1500 psi − 200 psi = 1300 psi usable.
Execute + evaluate. 1300 × 0.28 is 364 L. At 8 L/min, a little over 45 minutes is reasonable.
RAGE is a problem-solving scaffold, not a mental-health treatment. The purpose is to reduce the number of decisions you have to hold at once and help you restart the calculation with one defensible move.
Notice: The environmental context changes the urgency, not the arithmetic relationship.
On a remote rescue, the helicopter could not land near the patient, so our team went in on foot. The patient had sustained a significant head injury after an off-road crash. Ventilation was adequate, but oxygen saturation was low, and oxygen was being delivered by nonrebreather mask at 12 L/min.
In the jump bag we had a full small D cylinder at about 2,000 psi. For that cylinder setup, the factor we used was 0.16. The trip back to the aircraft was long, hot, rough, and slow. A ground ambulance was staged in another direction.
The question was not academic: did we have enough oxygen to commit to the route back to the helicopter, or did we need to divert toward the ambulance?
I ran the calculation while we were moving:
Duration (min) = k × (PSI − 200) ÷ flow
0.16 × (2000 − 200) ÷ 12 = 24 minutes.
That number gave us a usable decision window. We continued toward the aircraft and arrived with a little under 400 psi remaining.
The formula itself was simple. The value came from being able to retrieve it, execute it, and turn the answer into a decision while moving a patient over difficult terrain. “24 minutes” was not merely a number on paper; it was a forecast of a limited resource.
This is a retrospective educational account. Cylinder factors, reserve thresholds, equipment, oxygen-delivery practices, and local protocols can vary. Use the specifications and guidance that apply to your setting.
Practice is more useful when you have to retrieve the relationship, apply it, receive feedback, and encounter it again after the surface details change. MedMathMindset uses retrieval, spacing, feedback, confidence calibration, and contextual variation as educational design tools—not as promises of instant “brain rewiring.”
Retrieval practice → · Cognitive load → · Evidence standards →
This public lab gives you the relationship, examples, one interactive attempt, a changed wrapper, and a problem-solving scaffold. An enrolled pathway adds personalization, repeated practice, spacing, provider-specific progression, performance signals, and longitudinal history.
See the learner system →