Tuesday, August 19, 2008

Fuse Types, Characteristics and methods of Joining: Part 3


GREEN PLASTIC IGNITER CORD

This fuse burns slowly, at about 25mm (1inch) per second. It is normally used to provide delays at ignition points and in sequences. It sometimes serves as the initial point of ignition for the fireworks.

Connecting green to green is done by twisting 25mm. or so and taping, green to quickmatch by inserting at least 25mm into the core and taping, quickmatch to green by stripping the plastic sleeve (to aid the transmission of the flame use tape wrapped around the plastic sleeve which when pulled back reveals the brown core) and inserting the incendiary into the central core of the quickmatch and then tying with a cable tie if required and/or tape.

BROWN PLASTIC IGNITER CORD

May be worked in a similar fashion to green, however it has a considerably faster burning rate and to avoid confusion should be kept away from the general fusing process unless specifically required.

Other Fuse Joints (Spanish Delays and Pressed Delays)



You can either have a fuse join that finishes at the delay in which case simply reveal 25mm or so of the Quick Match, place this is the end and secure using a cable tie or string. If you wish to join a number of varied time delays together to create several delays from one line of Quick Match then fold the quick match over and cut the end to reveal the internal fuse as shown above.



Once you have done this place the double strand in (exposed end first) and secure in using a cable tie or string.

These fuses can be used to provide delays between sequences of various items or used as a method of delaying shell in the same way as using PIC. Delays are generally more accurate but are more costly, but the benefits can out way when firing to music etc. You must also remember that pressed delays in particular can burn quite viciously and this must be considered when securing them down due to unwanted burning to surrounding fuses, other items and even wooden racks

Safety Considerations When Fusing

The following points must be taken into consideration with regard to fusing before you arrive on site:-

Fusing away from the workshop may only take place on the site of the display,
even though more than one day may be required to prepare the fireworks.

If the weather is poor and you require shelter, fusing may only take place inside a tent or cover of light fabric material or vehicle with a light fabric roof – never in a building.

Only use proper supplied cardboard / fibreboard tubes, high performance
polyprene or UPVC tubes for mortars and shells. Never use steel pipes or
lightweight drainpipes (they also sweat).

Handle quickmatch with care. Cut off what you need and put the rest of the bundle back into the storage container.

When joining quickmatch avoid cutting the incendiary cores. Where cuts must be made, only sharp scissors, nips or very sharp knife may be used. Do not tear fusing apart.

Keep all fusing dry and generally consider total waterproofing of the fireworks display. Bases of buried cardboard tubes should be bagged, open ends of tubes covered with foil or bags secured with rubber bands or tape, cake boxes covered with polythene, flights with thin aluminium foil (which must be taped down to prevent it being dragged off with the first rocket), candles wrapped with polythene etc.
Remember to remove waterproofing from rockets before firing!

Secure all joins so that they cannot be snatched either by accident or during
ignition.

Never use staples to secure fusing. Always use battens with cable ties or the cable ties themselves tape to secure them to the Shell Frame, tape can also be used (gaffer tape) but tends to be less reliable and the PIC can rip stopping the sequence

Do not set green cord along a surface and then cover in tape as it will burn more quickly.

Keep the work site tidy.

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