user25575: I'm looking for a mechanical component that enables me to do two things:

contain a gas in a bottle and if opened, the gas should smoothly flow out (with the same pressure as a child blowing out candles on his birthday cake)
a valve for the bottle that can be opened by an Arduino when powered via USB

I already figured out that there are outlets for CO2 capsules. This could work, but then I'd need to figure out a way to decrease the pressure in order to receive a gentle gas flow. 
Do you know any better approaches? Thanks in advance!

user313: If you can tolerate a decreasing flow as the pressure in the bottle drops, a simple restrictor (fluidic equivalent of a resistor) will limit the flow but of course, I = E/R; the flow will be proportional to the bottle pressure. If that is acceptable, it is probably the cheapest, simplest, and most reliable way.

25575: <p>I'm looking for a mechanical component that enables me to do two things:</p>

<ul>
<li>contain a gas in a bottle and if opened, the gas should smoothly flow out (with the same pressure as a child blowing out candles on his birthday cake)</li>
<li>a valve for the bottle that can be opened by an Arduino when powered via USB</li>
</ul>

<p>I already figured out that there are outlets for CO<sub>2</sub> capsules. This could work, but then I'd need to figure out a way to decrease the pressure in order to receive a gentle gas flow. </p>

<p>Do you know any better approaches? Thanks in advance!</p>
 313: <p>If you can tolerate a decreasing flow as the pressure in the bottle drops, a simple restrictor (fluidic equivalent of a resistor) will limit the flow but of course, I = E/R; the flow will be proportional to the bottle pressure. If that is acceptable, it is probably the cheapest, simplest, and most reliable way.</p>
