For an adult oxygen cylinder (D size) at a gauge of 1,200 psi, what is the operating time at a flow rate of 10 L min⁻¹?

To determine the operating time of an adult oxygen cylinder with a D size at a given gauge pressure and flow rate, you need to consider the cylinder's volume and pressure.

A D size oxygen cylinder typically has a capacity of about 0.4 cubic meters, or 400 liters, of oxygen when full at standard pressure (usually defined as 690 psi for D cylinders).

Using the gauge pressure of 1,200 psi, we must first convert this to a total pressure relative to standard pressure. The operational pressure for calculations is usually taken at absolute pressure, which is the gauge pressure plus atmospheric pressure (approximately 14.7 psi). Therefore, 1,200 psi + 14.7 psi = 1,214.7 psi.

Next, we calculate the usable volume of oxygen in liters at the given pressure using the formula:

[ \text{Oxygen Volume at Gauge Pressure} = \text{Cylinder Volume} \times \left(\frac{\text{Gauge Pressure}}{\text{Standard Pressure}}\right) ]

This results in:

[ \text{Usable Oxygen Volume} = 400 \text{L} \times \left(\frac{1214.7}{690}\right) \