Calculation for knowing duration of gas cylinder

In summary, when calculating the total duration a gas cylinder will last, you need to know the flow rate, initial temperature, volume, and pressure of the gas, as well as the outlet pressure and geometry. The temperature of the gas and assumptions about the system can also affect the calculation. If the cylinder is a liquidified gas cylinder, only the mass of gas remaining can accurately predict when it will be empty.
  • #1
Rahul Das Gupta
2
0
I know the total volume of a gas cylinder, the pressure in it, and the outlet pressure that needs to be maintained. The flow rate is also known. How should I calculate the total duration the cylinder will last? Also, what should vary if the cylinder is a liquidified gas cylinder?
 
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  • #2
PV = nRT

Knowing the flow rate at some given pressure and temperature you should know the number of moles of gas leaving the cylinder per second ( or minute or hour, what ever unit of time your flow rate is in). Also, you know the number of moles of gas in the cylinder if given the initial temperature, volume, and pressure of the gas.

If stuck on a problem like this write down the equation you are likely to use and then write down what you know.
 
  • #3
The answer here depends on a few things. For starters, you need to know the geometry of the outlet and the pressure ratio of the outlet pressure to ambient pressure. You also will need to know the temperature of the gas in the bottle (and decide whether or not you want to assume it is constant or assume the system is adiabatic, etc.). Depending on the assumptions and operating parameters, this can be a very simple problem or a very complicated one.
 
  • #4
Welcome to PF.
Rahul Das Gupta said:
Also, what should vary if the cylinder is a liquidified gas cylinder?
Only the mass of gas remaining will give you a longer term prediction of empty than will gas pressure.
You will need to weigh the empty cylinder or read the tare mark to know where zero will be.
 

1. What is the formula for calculating the duration of a gas cylinder?

The formula for calculating the duration of a gas cylinder is: Duration = Cylinder Volume / (Flow Rate x Pressure)

2. How do I determine the volume of a gas cylinder?

The volume of a gas cylinder can be determined by multiplying the cylinder's height by its cross-sectional area. The height and cross-sectional area can be found on the cylinder's label.

3. What is the flow rate for different types of gas cylinders?

The flow rate for different types of gas cylinders can vary depending on the size and type of gas being stored. It is important to refer to the manufacturer's instructions or consult with a gas expert for the specific flow rate of a particular gas cylinder.

4. Can I use the same calculation for all gas cylinders?

No, the calculation for determining the duration of a gas cylinder may vary depending on the type and size of the cylinder. It is important to use the correct formula for the specific gas cylinder being used.

5. Is there a more accurate way to calculate the duration of a gas cylinder?

Yes, there are more accurate methods for calculating the duration of a gas cylinder, such as using a gas flow meter. However, the formula provided is a good estimate for determining the duration of a gas cylinder.

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