Pyrotechnic delay detonator

[amagroup]

I am tryingto manufacture the pyrotechnic delay detonator for various delay timings.

The problem I encounter is , I am not getting accurate timing for 17 millisecond (ms) 25 ms. I use red lead , silicon mixture.

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You need to be a lot more specific. What's the ratios of your composition, loading diameter and pressures, column length, etc.

NBK

[amagroup]

I am using red lead, Silicon powder- grain size 1 micron & zirconium powder in 70:20:10 ratio.

Filling of this composition in lead tube of 8 mm ID & 16 mm OD which is drawn to 6.3 mm OD.

The drawn tube is cut in 4 mm ( This is the minimum length I can cut with my machine ). It is then pressed in detonator shell at 8 kg / sq. cm pressure
Crimped with shock tube & tested for delay time.

On testing it gives irraitic timng ranging from 10 ms to 30 ms

I need suggestions to improve the technic / composition so that I could get consistant results for 17 ms , 25 ms.

[nbk2000]

Problem might be cracking in the compressed column upon cutting the tube. Or maybe the column ends are being crumbled a bit?

[Bert]

Drawing down a maleable tube is likely to crumble the filling, resulting in uneven performance. How and why did you select this method?

[Crazy Swede]

The method of drawing out a lead tube down to a smaller diameter, and while doing so compacting the contents of the tube, is an old but sometimes surprisingly good way of producing long columns of pyrotechnic delay compositions.

I haven't heard of anyone still using this technique nowadays though since lead is banned in a rapidly increasing amount of applications.

Except trivial problems like moisture and uneven blending of the composition, it is very likely that the reason for varying delay times has something to do with the formation of gas! This is especially important if the delay element is ignited through a shock tube that can apply different amounts of pressure depending on what lenght is used or if it cracks or not.

Since no composition is truly gasless it is very important to be aware of that the gas pressure above and below the burning front will affect the reaction rate and therefore the delay time. What kind of binder is used? Binders are common sources of unwanted gas formation.

To achieve reproducible gas pressures it is sometimes necessary to use a priming composition that leaves a solid slag that acts like a plug and gas seal on top of the delay column. Also, it is often important to add an ignition composition at the bottom end of the delay column that is extremely fast and hot burning to avoid the last increment of delay composition to chip off or being shot out from the gas pressure inside the column before being ignited.

Another thing to look at is the quality of the Zirconium powder. Different batches can vary a lot in several ways!

[amagroup]

Thanks for your information, as mentioned by you & others I would like to know what is the substitute for drawing of lead tube?
How can I make pyrotechnic delays for detonators by any other methods?

[Crazy Swede]

No offence but where do you live?

In the rest of the world pyrotechnic delays are most commonly pressed in aluminum tubes by gang rammers and small increments of loaded pyrotechnic composition!

[amagroup]

[QUOTE=Crazy Swede]No offence but where do you live?

Basically,what I am doing is as follows
Aluminium or steel tube of approximatly 6 mm internal diameter is filled with PETN as base charge having initiating ecplosive above it ,both pressed independently; now a delay element which is having pyrotechnic composition filled in lead tube & drawn to 6 mm OD is cut & pressed over an initiating explosive. This is what I know to the best of my knowledge
can you tell me hou should I go fot the latest technology or where do I find it

[Crazy Swede]

...can you tell me hou should I go fot the latest technology or where do I find it...

Yes I could, but I will not if you don't explain why you're experimenting with detonators using such old-fashioned techniques! Where do you live?

[nbk2000]

Probably lives somewhere very hot and very dry, with really cheap gas. ;)

[Cobalt.45]

This is what I know to the best of my knowledge
can you tell me hou should I go fot the latest technology or where do I find it

Why the fuck don't you hook up with abdul dereamer and compare notes. At least you both would have a language in common, and a religion... and an agenda.....

[amagroup]

Yes I could,

well, I am in INDIA , Nagpur and a chemical engineering student working on pyrotechnic composition. I hope this will suffice

[c.Tech]

You could at least close your quotes and use proper spaces between your commas and full stops before demanding to be spoon-fed information, which I should point out both are bannable offences.