6 replies to this topic

[teaboy]

Does anyone have (or know where I can get) some data about the safety and performance of different mortar tube materials? I know that insurance companies prefer fibreglass and for tubes to be separated in racks, along with the 1m per mm distances, but I can't find any test data to explain why.

If I spend money on materials to improve the safety of displays I'd like to actually KNOW it will help.

Any ideas?

[Arthur Brown]

A thorough search of pyrouniverse forum (racks and mortars) will bring out many threads where americans have tested rack designs, some hold up better than others, but they are usually for their consumer shells which are less than 2".

[Mixologist]

Contact Shellscape for thier test results.

[Malcolm Smith]

Does anyone have (or know where I can get) some data about the safety and performance of different mortar tube materials? I know that insurance companies prefer fibreglass ---

Perhaps misguided.

I have many HDPE tubes and some glass fibre. HDPE have never given any problems over many years of use.

Some of the GF tubes have spalled and show signs of gas leakage after not that many shots and, since they have never been thrown about, it is almost-certainly due to gas pressure damage.

This prompted me to request life data from the Chinese.

Vulcan's reply was "The usage life of fibre glass mortar tubes depend on how they are maintained and used and how often they are being used. They can last a few years but you do need to keep a regular check on them to make sure they are still in good condition. Usage can range from average of 12 times to over 20 times."

Regarding your other query about safety distances, one needs to allow for a ground burst.

Here is some data on actual video measurements of Horse peony and Sunny ring shells.Selected Pyrotechnic Publications of K. L. and B. J. Kosanke

http://tinyurl.com/cr6n6d

Page 80 Average burst radius of Horse 5in/125mm shells 150 feet/45 metres.

Vulcan's data on the burst radius agrees http://www.firework....shelldata09.pdf

I have a Canadian paper on destructive tests of mortars - will post some extracts later.

Edited by Malcolm Smith, 19 September 2010 - 11:44 AM.

[Malcolm Smith]

Here is a table from 'Evaluation of firework mortars' by E. Contestabile, R. A. Augsten and T. R. Craig of The Canadian Explosives Research Laboratory. http://www.nrcan-rnc...sci-sci-eng.htm

Fibre, in these tests is fibre reinforced epoxy with a wood plug rather than polyester resin with fully moulded plug as used in Chinese mortars. Because a fully moulded gf mortar does not have the weak spot of a fitted base plug, it is more likely that the tube itself will disintegrate completely.

Note that schedule 40 steel mortars survive even flash maroons below 125mm.

[phildunford]

12 to 20 times, that seems so little. what would people expect for a average glass fibre mortar, is this about right?

I visited Malcomb a couple of months to interview him for Spark (interesting guy!).

I would say that the general opinion is that fibreglass mortars last 'for ever' but Malcombs extensive practical experience would suggest this is far from the case.

Certainly food for thought. Give your fibreglass mortars a good visual inspection before you use them and discard any that are even slightly suspect.