I Is it possible to propel a spray can with gunpowder?

[GulfOnBoard]

TL;DR Summary

Is it possible to propell a spray can with gunpowder?

Is it possible to pressurize a spray can with gunpowder or something similar, in order to make a reliable spray can with high pressure?

I’m asking this question because a small amount of gunpowder generates a huge amount of propelling gasses when ignited. I need to make a compact spray can, and I don’t want to store the can pressurized but instead pressurize it at the moment when I’ll use it.

 

[Nik_2213]

Sounds like cars' airbag tech. Their 'gas generator' is far from benign. Due Care, Please ??

 

[A.T.]

I need to make a compact spray can, and I don’t want to store the can pressurized but instead pressurize it at the moment when I’ll use it.

Look at how some fire extinguishers work.

 

[jrmichler]

Have you considered a pump sprayer? Always works, never loses pressure, zero volume taken up by pressurizing substance, safer, and better for the environment.

 

[GulfOnBoard]

Have you considered a pump sprayer? Always works, never loses pressure, zero volume taken up by pressurizing substance, safer, and better for the environment.

Do you mean a water pump/electrical enginge? I haven’t seen any such device for high pressure that’s small.
If you mean this: kind of pump sprays, they are not powerful enough, I want the spray can to be equivalent to a highly pressurized fire extinguisher.

Will this design work?

If I use modern (smokeless) gunpowder the pressure will be way too high and the spray can will deliver the liquid like a shot. If I use black powder, even though it generates lower pressure than modern smokeless propellant, I still believe that it will also burn way to fast for this application.

A slower burning powder, like those used in model rocketry, may work better?

(The design above need a source of ignition and a vent hole for the burning gasses to escape through, which I did not include in the picture)

 

[Anachronist]

That's basically a cannon with a restricted muzzle. Sure, it could work, if your intent is to empty the whole can. What's the application for this? Your initial post said "reliable", and I'm not sure this will be.

I think a better approach would be to use one of those small pressurized CO2 cartridges like what's used in paintball guns. Just one of them can inflate a bicycle tire to 100 psi. That should be more than enough pressure for your spray can. Because they are threaded, they are easy to replace.

 

[berkeman]

What's the application for this?

I think that's a key question for the OP to answer. There are just too many possibilities to consider unless we know the constraints of the problem.

 

[arydberg]

Perhaps a match head or a few of them. Wrap a lamp filiment around them to ignite. It would take some experimenting... be carefull.

 

[jrmichler]

What kind of spray pattern? How far does it need to spray? Is there a flow volume requirement? Is the liquid water? If not, what is the viscosity and surface tension? What droplet size do you want? The design of your spray nozzle has a huge effect on the pressure needed to spray a certain distance. If you only need to spray a liquid with properties similar to water a distance of 20 feet, and do it with large droplets, then a pump sprayer with a properly designed nozzle will do the job.

I once made a simple nozzle with a 0.040" diameter hole for the end of a garden hose. At about 50 PSI, it would shoot a stream over the roof of the house. It was dangerous. It felt like that small diameter solid stream could puncture my skin, so I destroyed it.

I then made another nozzle. This one had a 0.040" diameter orifice aimed at a plate at about a 15 degree angle. That made a fan spray with impressive range and no danger of puncturing skin. It was a way for my daughter to play with a hose without wasting much water.

Design the nozzle first, then determine what pressure and flow rate you need to get the spray you want.

A pinhole hydraulic leak in a logging machine hit one of my uncles on a finger tip, and injected hydraulic fluid all the up to his elbow. He was lucky, the doctors were able to save his arm and hand, but that arm and hand were permanently partly crippled. Mobil hydraulic systems typically run at about 2,000 PSI. The paper mill had a high pressure water system for high pressure washing of machinery. That system ran at 1000 PSI. The safety training including cutting a wood 2 X 4 (50 by 100 mm) in half with the wash gun, followed by the announcement that any horseplay would result in immediate termination of employment.

Stay away from gunpowder. Smokeless powder regularly burns at 50,000 PSI, black powder at pressures over 5,000 PSI. Run some tests, find what pressure you really need, and think very carefully before designing anything that needs more than 100 PSI.

 

[Vanadium 50]

I keep looking at the title and think "I bet I could get the can flying a couple hundred feet..."

 

[hutchphd]

And of course the Huygens gunpowder engine:

https://en.wikipedia.org/wiki/Gunpowder_engine

 

[jrmichler]

I keep looking at the title and think "I bet I could get the can flying a couple hundred feet..."

Don't bet any money on that. Setting a can on the muzzle of a cannon pointed straight up gets the can pieces to a maximum of treetop height. It makes no difference whether it's a small pop can or a gallon can. The can gets ripped into several pieces that quickly orient into the maximum drag orientation, so they do not go far. Wood chunks from a wood cable spool go farther. And it's dangerous - those sheet metal pieces have sharp edges.

Gunpowder does not work for can rockets. Smokeless powder, if not confined, burns with a fiery WHOOSH. Black powder explodes even it it's not confined.

BTW, when my father died, I got rid of 30 lbs of smokeless gunpowder. Make a pile, added a powder train, threw in a match, and it was gone with a WHOOSH. But not an explosion. My father tried that with one pound of black powder. It was a good thing that he had a fuse long enough to get well away because anybody close would have been hospitalized.

 

[anorlunda]

You can do much better than gunpowder. See:

https://en.wikipedia.org/wiki/Aerosol_spray#Aerosol_propellants