BP Fuel Drying Time

[nater]

How long does BP fuel granulated with water / alcohol usually take to dry out in open air? Just an hour or two in the sun, overnight? I'm planning on making around 8 oz for my first rockets at a shoot next weekend.

[dagabu]

It depends since relative humidity, air movement and temperature all play rolls in drying time. If I make a kilo of BP, I simply weigh it after 24 hours and see how close I am to the 1k. Usually, 2% residual water is no big issue, in fact it can actually speed up the burn rate.

 

If I dry it in the dehydrator, it only takes over night to dry, if i leave it out to dry, it may take several day to weeks in humid conditions.

[nater]

Thanks, it has been fairly dry out here, so I'll see how quick they dry. Our shoot is a week away, so I might have just enough time. I probably have some desiccant bags if I need to speed things up.

[Mumbles]

With nothing more than good airflow, my BP dries in 2-3 days usually. A box fan will do. Stir the BP a couple times per day, and maybe change the paper after the first day, and you'll have no problems.

[ChrisNZ]

I personally just made a batch of 6:3:1 ^{(KNO3:Charcoal:Sulphur)} and didn't even think of granulating it for use in rockets, I just rammed the powder into a tube and drilled cores.

 

I'm no expert but I would think that ramming granulated BP would defeat the purpose of having granulated it in the first place as after it's rammed there's no gaps for air to pass through for it to burn faster?

By ^{^}that^{^} I mean, 'Can someone with more experience confirm or deny?' that'd be awesome.

 

Though Nater if you haven't tried it, mix up some 6:3:1 for rockets. I milled mine for maybe two hours and got great results, come to think of it I even ued the 6:3:1 for some of my first black match just added 3% dextrin and some water to make it gooey, pretty much just held some string in it under my finger and pulled the string through.. That took about three hours of drying in the sun with a slight breeze before it felt 'crisp' as if it was dry. Left it overnight in a container with some Damp Rid. It's what I used as fuse in my rockets too.

[Mumbles]

Granulating rocket fuel has the advantage that it is less dusty and messy to work with.

[ChrisNZ]

Granulating rocket fuel has the advantage that it is less dusty and messy to work with.

 

Straight away I can see this making sense now.. I imagine I had a wee bit of waste powder that 'puffed' out the side of the rammer when I made mine, cleaner hands sound good too. Might try granulating the next batch!

[nater]

The formula I am planning on using is for the U/H type spindles. 70/20/10 +5 Dextrin ~20% water / alcohol. I will probably try a tiny batch just screened, but I recently rammed some smokes and the dust puffed up everywhere. It seems like a week is plenty of time, so I should have nothing to worry about.

[Updup]

Straight away I can see this making sense now.. I imagine I had a wee bit of waste powder that 'puffed' out the side of the rammer when I made mine, cleaner hands sound good too. Might try granulating the next batch!

 

If your going to use it for rockets though, make sure you don't add a binder.

[Col]

I add mineral oil to the milled bp, screen a few times to mix after adding the coarse charcoal. Into the drying box for 24 hours and then press the motors. Not too scientific but no dust, it works for me.

[dagabu]

Mineral out slows the fuel down considerably, even 1% can reduce the burn rate by 25% or more.

[WSM]

When I lived in a drier clime, I'd "wet mix" BP rocket composition in the evening and it was ready to press or ram the next morning. I'd usually store it in a cardboard box so the RH would balance with the environment. Even where the RH is higher, the higher moisture content dosn't seem to cause any problems for BP rockets (any moisture actually adds to the thrust by including water vapor with the other exhaust gasses).

 

The reason for quotes on the wet mix method is I don't over-do the moistening. When I add water to the BP, I only add enough to just do the job. It's certainly not wet, just moist. When thoroughly mixed and moistened it looks like dry cake mix or brown sugar (~3-5% water), and is spread on a layer of paper to dry over night. I don't add alcohol unless the mix is hard to wet for some reason. Plain water does just fine, in fact, hot water would probably do a better job!

 

Have fun and report back, please.

 

WSM

[psyco_1322]

A fine layer of granulated bp spread out will dry in about a day or so with a fan blowing on it.

 

Mineral oil is shit, dont use it unless you want your bp rockets strobing...and that takes usually 5-6%. If you want to bind it with something, try wax at about 2-3% really helps consolidated the fuel. You can add dextrin, but the grains will be hard, and if you dont have a big enough hammer the grain can be weak, about 3%...I think SLD told me 5%, but i think thats a little excessive. Red gum at 2-3% would be ok too, better than dextrin actually.

 

You don't need to desiccate your bp...unless you just like making things difficult.

[donperry]

I'm trying to find a thread here that describes how to make BP without boiling/heating. Like using alcohol for example.

 

What i'm thinking is to grind the kno3 by itself, then put that it a pan with the other two (yellow powdered sulfur+charcoal) and add alchohol to make a solution then let it dry overnight, over a few days

 

will that work guys? I'm new here.

[Bonny]

I'm trying to find a thread here that describes how to make BP without boiling/heating. Like using alcohol for example.

 

What i'm thinking is to grind the kno3 by itself, then put that it a pan with the other two (yellow powdered sulfur+charcoal) and add alchohol to make a solution then let it dry overnight, over a few days

 

will that work guys? I'm new here. Look into a ballmill, and then you're on your way.

 

 

START by reading the many threads on BP. You'll find the answers you're looking for there.

Edited February 5, 2011 by Bonny

[donperry]

Yes, i've been doing that. thanks Edited February 6, 2011 by donperry

[Peret]

Some desiccant comes in handy for drying powder and stars if the weather is too humid. Silica gel is the most common, or you can use calcium sulfate (gypsum). Roast raw gypsum in the oven at 350-375F to dehydrate it, but not too hot - above 450F it becomes irreversible and won't work. Gypsum can be picked up for free if there's a quarry near you or it can be purchased. Put the desiccant in a paper bag, then it and the powder inside a sealed plastic bag or container. Both silica gel and calcium sulfate can be recycled indefinitely by drying in an oven - 250F for silica gel, 350F for calcium sulfate - though the indicating kind contains cobalt chloride, which is mildly toxic and shouldn't be used around food.

[Guest no6]

I'm trying to find a thread here that describes how to make BP without boiling/heating. Like using alcohol for example.

 

What i'm thinking is to grind the kno3 by itself, then put that it a pan with the other two (yellow powdered sulfur+charcoal) and add alchohol to make a solution then let it dry overnight, over a few days

 

will that work guys? I'm new here.

 

It depends on what you want to use your BP for. Start here. Second one down. Here.

[Guest no6]

Then look to the left of your screen for Fireworks info charts and tables.

[donperry]

thanks

[MadMax]

I can make some nice hard granulated bp that dries in close to 20 min with a process I've come up with...

 

The first thing I do is prepare my "red alcohol". To do this I simply buy 100% methyl alcohol and desolve in that as much red gum as it will take. It usually ends up looking kinda like koolaid. Then I filter this through a coffee grinder to get out particles and put the filtered mix into a spray bottle. In order to effectively wet the mix evenly and with as little dicking around as possible I dump fine milled BP into a ziplock bag and spray it a few times and them mix it in and spray again and mix until it slowly and evenly turns to the consistency of clay. I form the BP into a ball then run that over a cheese grater evenly spreading the BP on a piece of foil or paper. As I grate the ball it will dry in the air so I respray it as needed.

 

I tend to avoid using water as it takes way too long to dry and tends to dissolve the KNO3 which then recrystallizes on the grains and forms a whitish layer.

 

I find that it helps to lightly sprinkle some milled bp onto the drying granules to speed up drying and sort of micro-prime them. I do this with a salt shaker full of milled bp that I keep handy (sign of any good pyro )

 

If I'm in a hurry I can speed up the drying process by dumping the bp granules into a screen and use a hair-drier rigged to blast warm air through the bp and screen. That can dry it out really fast.

 

Another way I've dried it is I have put it under a heat lamp although I would not recommend doing this unless you have a small amount and in a place where it can't do any damage if it ignites.

 

Of these 2 methods the hair-drier is faster. If you are really determined you can probably get the grains dry in 5 minutes with a hair drier.

 

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On the other hand if I want to pack the powder into tubes I would not recommend mineral oil. It's too thick and hard to spread evenly. You could try using gasoline instead to wet to the consistency of clay. Because like 98% of it evaporates and leaves behind an oily residue that would be evenly spread across all the particles. That oily residue is all the hydrocarbons that are too heavy to evaporate from the gas. Then once wet kneed then dry, crumble and then re-powder it and dry further. Once completely dry it should be less dusty.

 

I haven't tried the gas method for bp but I have used it on other powders to oil coat them. What I normally do for making bp pack dust free is stick the milled bp in a ziplock as before and spray in 2-3 sprays of the red alcohol and mix it in well. I let it dry in the air for a few minutes then put back in the bag and spray 2-3 sprays again. It'll have so little alcohol in it that it won't even seem wet but is quite a bit better dust-wise. Doing this'll ensure a more solid grain and keep the dry time minimal.

Edited March 8, 2011 by MadMax

[donperry]

^ phenomal Edited March 8, 2011 by donperry

[dagabu]

There are a lot of risky things that you are proposing here that in my opinion are not worth the risk. Except for doing this outside in a warm breeze, I cannot think of a place where this would be safe to do.

 

The hair dryer is a heated coil with air being pushed across it. While this may work for you, I dont think it should be recommended for use.

 

Anyone that has had only 50 grams of BP go up on them knows the enormous heat that is generated with even such a small amount, I cant even imagine the heat that comes off a full batch.

[MadMax]

Dagabu,

 

Thank you for your opinion. I agree that it's not generally a good idea to actively heat any composition. I do however take several precautions to mitigate the inherent danger. The very first thing I did is picked up a non-contact IR beam thermometer. This has been a godsend to me as I can instantly measure the exact temp of something from a safe distance. I periodically monitor the temp to ensure it constantly stays at a comfortable 45 deg C - much lower then the autoignition temp (I believe its around 400 deg).

 

Note: This thing kicks ass by the way. I think every pyro should have one!

http://www.amazon.com/Raytek-MT6-Non-contact-MiniTemp-Thermometer/dp/accessories/B000O80B5M

 

I don't do this in my house but I don't exactly do it outdoors either. I do it in an outdoor enclosure which is empty and inert but with ventilation. This way there's no danger of a fire if it ignites. I only make small amounts at a time. As a general rule of thumb the amount I make and warm is less then or equal to the amount that I wouldn't mind someone throwing a lit match into at any given time.

 

As far as how the hair drier is being used I have an aparatus I made that holds the powder in a screen basket and angles it about 30 degrees to the side. The aparatus includes a hair drier that is fixed at a 30 degree downward angle and blows warm (not hot) air onto the composition from about 2-3 feet away. The distance and heat setting can be used to vary the temperature and strength of the wind. This is all controlled remotely by a power strip. When I go to retrieve the powder the power strip is turned off and left to cool for a few minutes.

 

This is not a method to produce lots and lots of BP. It's more/less a method to produce a small quantity of granulated bp very quickly.

 

For larger batches I wouldn't heat it at all (except maybe the sun). But the above method with the red alcohol alone is enough to significantly speed up the drying time even when no heat is applied.

 

I would also not recommend doing this unless you have the non-contact thermometer - a crucial piece of hardware in my experience.