PSI has nothing to do with "gas capacity" 5" latex balloons take .06 cubic feet of air, nitro, or helium. Don't use helium in 5" latex balloons, but I'm sure you know that.
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Filling balloons with air by: Margit
You mentioned a pressure of 2000 - do you know in which units the pressure is measured in your canister? Most common ones are pascal (pa), bar and atmosphere (atm).