Magnesium/KNO3 Igniters and Safety

[blackbrandt]

Hello,

I am new here, so try not to be too hard on me... I am trying to learn while being as safe as possible.

 

I launch rockets. More specifically, I launch commercial motors (however, I am starting to work under a mentor on making sugar propellant. I am a Tripoli Rocketry Association member (for those who were wondering).

 

Anyway, I am starting to work on igniters. This is the one I am working on at the moment. For those who do not want to click, the recipe is Magnesium powder, epoxy, and potassium nitrate (in a 12:5:3 ratio respectively). However, I am trying to figure out a few things about it.

 

What is the purpose of the potassium nitrate? I know it is an oxidizer, but what purpose does it serve in the reaction?

 

And magnesium. If I am not mistaken, the magnesium is for igniting the motor itself. It burns at about 5000F, or so I am told. However, the recipe asks for 300 mesh. I can only find 250 mesh. Would this still work, or would it be too coarse?

 

 

I have been doing research for the past few days, but most sites seem unreliable. If the site recommends mixing Magnesium and KNO3 together dry, I assume the site as not very smart, and click away.

 

 

Also, are there any good sites where I can do some reading about safety while working with these chemicals? So far, what I have gathered:

Water will not put out a magnesium fire (the water can form hydrogen gas, which will ignite explosively). Sand is the best for putting it out.

• Do not mix dry chemicals.
• No glass or PVC containers. Use wood stirrers and do not mix in a closed or near airtight container (if the mixture ignites, if it is in a bottle, it will explode the bottle, while if you are mixing in a dish, it will not explode the dish as easily).
• No open flames near the mixing.
• Wear a welding mask and gloves while handling the mixture. If the mixture ignites, it can blind you easily from the intense light. The gloves help protect your hands.

 

 

Is there anything that I am missing?

 

Also, are there any other decent recipes that you know of that will get to about 4000F or so?

 

 

 

Thanks!

 

Matt

Edited April 11, 2014 by blackbrandt

[nater]

"I launch rockets. Not the redneck "Hey, bubba, watch this!" firework rocket motors on youtube. "

 

Most of us here who build rockets, build firework rockets. A few are involved with HPR, and some both. There is no need to insult us if you want advice. I was instantly turnned off from getting back into sport rocketry by the snobbery of the HPR guys and their attitude against pyrotechnics.

Edited April 11, 2014 by nater

[blackbrandt]

Sorry, what I was talking about were the people on youtube who mix together dry chemicals in a glass jar while smoking in their kitchen right next to a propane tank with no safety devices whatsoever. I did not mean to insult you. My apologies.

[nater]

It's okay, just be clear that most people here make pyrotechnic rockets, so your help with HPR might be a little slim. There are plenty of threads on ignitors or e-match though, which may have exactly the information you are looking for.

 

I use commercial e-match or a fuse to light everything. I do not use magnesium either, so I don't have to coat it or use harsh solvents when binding anything with it. Aluminum and MgAl work fine for my needs. James Yawn uses black powder and a bit of magnesium to make ignitors. http://www.jamesyawn.net/38mm/index.html. Here is another method, using a commercial kit. FireFox Enterprises sells supplies for pyrotechnic and HPR needs.

 

For PPE, I would not want to work wearing a welding mask, if you are worried about the brilliant flash from an accident, an auto darkening mask would be your only choice. Otherwise, you would not be able to see very well.

 

Carefully mixing dry chemicals is just fine. Depending on the mixture, you will want to avoid any possibility of friction, static or other sources of sparks. A respirator is helpful and mandatory with certain chemicals.

 

Otherwise, gloves, long cotton pants, long cotton sleeves, an apron, some type of eye protection are the best things you can wear. You want to avoid most synthetic fibers when working with anything flammable. Nomex is fine, nylon will burn and melt into your skin.

 

FYI, as a firefighter, enough water will put out a small magnesium fire. There is an impressive reaction, which you need to be prepared for and protected from. Foam (AFFF) is what is commonly used. Sand will work. That said, unless you are a professional with the training and tools, don't put water on a fire fueled by flammable metals.

Edited April 11, 2014 by nater