Calculating CO2 Concentration For Pepper Spray Devices

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SUMMARY

The discussion centers on calculating CO2 concentration for pepper spray devices, specifically addressing the confusion between liquid CO2 and gaseous CO2 as propellants. Participants clarify that liquid CO2 requires low temperatures and is not typically used in spray cans. They emphasize the distinction between concentration and amount, indicating that different formulas or ratios are necessary for accurate calculations. The conversation highlights the need for precise terminology and understanding in scientific inquiries related to aerosol devices.

PREREQUISITES
  • Understanding of gas laws and phase diagrams, particularly CO2 behavior.
  • Familiarity with aerosol mechanics and propellant types.
  • Knowledge of concentration versus amount in chemical contexts.
  • Basic principles of thermodynamics related to gases and liquids.
NEXT STEPS
  • Research the CO2 phase diagram to understand its states and properties.
  • Learn about the calculations for gas concentration in aerosol applications.
  • Investigate the use of liquid nitrogen in aerosol products and its implications.
  • Explore the differences between concentration and amount in chemical formulations.
USEFUL FOR

Students, educators, and researchers interested in aerosol science, particularly those focusing on propellant chemistry and the physical properties of gases and liquids.

mzuern
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TL;DR
I have a kid who wants to do a report on aerosols.
I have a kid who wants to do a report on aerosols. As I understand, we have researched that for pepper spray devices liquid CO2 is used as a propellant, but we can't find out how they calculate the concentration. Is there a place we can find the right formulas needed?
 
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mzuern said:
Summary:: I have a kid who wants to do a report on aerosols.

I have a kid who wants to do a report on aerosols. As I understand, we have researched that for pepper spray devices liquid CO2 is used as a propellant, but we can't find out how they calculate the concentration. Is there a place we can find the right formulas needed?
Welcome to PF.

It's unlikely that they referenced liquid CO2, since that requires very low temperatures and typically dewars are used for that, not spray cans

Please post links to the reading that you've been doing. Thanks.
 
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My mistake. It isn't liquid, but still how does someone determine how much is needed. Typically I think it only sprays for a maximum of 10 seconds. Is there a formula or ratio to determine amount needed?
 
Please post links to the reading you've been doing about this. Thanks.
 
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mzuern said:
we can't find out how they calculate the concentration
mzuern said:
Is there a formula or ratio to determine amount needed?

You seem to be using concentration and amount interchangeably - these are two different things, they mean different things and they can't be used freely one in place of the other (especially in the context of a school science project).

Please elaborate on what you want to find (and about the sources you consulted). It will really help us understand what you are looking for, right now we can only guess.
 
Liquid CO2 is pretty common at room temperature (and 80'ish bar IIRC) : that's the contents of the little tanks for seltzer bottles and some pellet guns ; it's the solid state that requires a low'ish temperature.

CO2 phase diagram

Maybe liquid nitrogen, which is used in spray cream, I think.
 

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