Aerosol Volume required for a Specific Pressure

[Denis]

Hi

I'm looking for some help in determining the volume of nitrogen required to produce a given pressure.

I've got an aerosol can with 160ml of head space that needs to be filled with nitrogen to produce an internal pressure of 10.5 bar.

How can I work out how much nitrogen will be required to produce the 10.5 bar?

Any help appreciated.

 

[CertifiedDataJunkie]

Help in determining the volume of nitrogen required to produce a given pressure?

Recalling some thermodynamics and general chemistry ...

Assuming the head space is incompressible and constant (unsure whether this is a good assumption) and ...

assuming the ideal gas law holds, PV= nRT ... so you are wanting to know the number of moles n in this equation

n = PV/RT = [(10.5 bar x atm/1.01325 bar) x (160 ml x 1 L/1,000 ml)/(0.0821 L*atm/K*mol x T (in Kelvin))

However, from thermodynamics, you need two properties to fix the state ... so you must also specify the temperature in the headspace. Also, heat will be generated by the process of compressing the gas unless it occurs very slowly or the heat of compression is removed.

once you know the number of moles n, you can calculate the volume of nitrogen from a source at a specified pressure and temperature using the molar volume ...

The molar volume of an ideal gas at 1 atmosphere of pressure is

22.414 L/mol at 0 °C
24.465 L/mol at 25 °C



So, there is an "answer" depending on the ability to further define the problem.

Anyone see any problems or something to add?

 

[Denis]

Thanks for the help / formula

I can't determine the temperature in the headspace, but nitrogen is being feed into the headspace - the cleanroom ambient temp is 19C. The liquid, which is 70/30 alcohol would be at about 14C.

The discharge from the small vessel (holding the nitrogen) into the aerosol can takes place in about 2 seconds.

Thanks for your help, but I still can't work this out - is it possible you could help me out here?