How to calculate the time for using an oxygen tank

Outside the cylinder in the air is 1 atmosphere of pressure, when we talk about pressure in oxygen cylinders we use the scale of psi.
1 atmosphere of pressure converted to psi (pressure pr. square inch) is 14.7 psi
Therefore, at a pressure of 14.7 psi, we have oxygen in the pipe equal to the volume V (behind the V on the neck of the oxygen cylinder). The tank is expressed in liters.
The amount of gas in the tank containing = (pressure gauge readings in psi multiplied by volume V Specified with the tank) / 14.7
For example, read the pressure on the gauge to 1,500 psi. The V value specified on the tank is 3.3 (0.5Q).
Amount of gas in the tank = (1500 x 3.3) / 14.7 = 336.7
Available time = Amount of gas in the tank that has / the rate prescribed by the doctor
For example, a doctor prescribes 3 liters per minute.
Available time = 336.7 / 3 = 112.2 minutes or 1 hour 52 minutes.

In conclusion

formula

1. The amount of gas in the tank with = (pressure gauge readings in psi x volume V specified with the tank) / 14.7
2. The remaining oxygen in the tank will be used for = the amount of gas in the tank that has / the rate prescribed by the doctor

example

1. V value specified on the tank = 3.3 (is the volume of water loaded in the tank)
2. Read the pressure on the gauge = 1,500 psi
3. Doctors prescribe oxygen for 3 liters per minute.

How to calculate the amount of gas in the tank with = (1,500 x 3.3) / 14.7 = 336.7
The remaining oxygen in the tank will be used for a long time = 336.7 / 3 = 112.2 minutes or 1 hour 52 minutes.