Friday, August 15, 2008

Fuse Types, Characteristics and methods of Joining: Part 2

Work on fireworks is only permitted, by law, at a Licensed Factory or on the site of a display.

As much as possible should be carried out at the factory, before going to the site. This has the advantage of working at licensed premises away from the public, and having a good supply of materials to hand.

Wherever you are working, bear the following in mind:-

No smoking, no drinking, no unauthorised use of drugs

Keep the work area tidy, clean up as you go

Use the correct tools for the work

Keep all fireworks not being worked on in covered boxes away from the work area.

Move prepared pieces away from the work area, set them up if possible.

Maintain minimum safety distances at all times. If on site, erect the barriers and keep the public away

Keep track of your tools and sundry materials such as fusing. It is easier to find these in daylight before the firework display than later on in the dark afterwards.

Keep fuses in a suitable container at all times. Handle them as little as possible.

If the prepared pieces are in any risk of becoming damp, they must be protected as an on-going task.

Quickmatch

This usually comes attached to certain shells in the form of plain brown paper and is not waterproof (unless plastic covered quick match is used and tends to be more popular these days). Working quickmatch usually comes in blue, brown or red plastic sleeves but other colours are available. It can be either single or double stranded or multi – cored. It burns at about 15m (50ft) per second and can be treated as instantaneous for practical purposes.

The core is very sensitive and must always be well protected by the sleeve. The waterproof sleeved type burns very violently and must be well tied to any connecting fuse. It must also be well secured to stop it thrashing or blowing away.

All quickmatch burns explosively and the pressure wave that precedes the flame can blow out connecting fuses if they are not well secured by tying with string or tape. It has been known, however, for quickmatch to be extinguished if it is bent too tightly onto a hard object e.g. lip of a mortar tube or cable tie.

Connect quickmatch by exposing the cores and placing in contact. Secure and join by tying and/or taping. Ensure that NO match is left exposed. Alternatively, the core can be connected by inserting into a hole pierced into the sleeve and securing well. Make sure that the core is in contact with the match core and not insulated between layers of the sleeve. Joins should be made “downward” to allow surface water to run off rather than run in. Gaffer or plastic tape should be used to waterproof the joint.



Quick Match to Quick Match – cut open as shown using sharp Stanley knife as shown on the left, then repeat as on the right, then overlay and tape together.




Quick Match to Quick match side joint – cut open each end as shown using a sharp Stanley knife, overlay the strands and tape as shown.

Shell linking is normally done with green plastic igniter cord (PIC) as a delay timer connecting the quickmatch fuses to each other. Keep the main run continuous, with a twist at each connection. The twist can be pushed into the open end of the match and taped over. Alternatively, a pressed powder delay can be used between adjacent shells. It is only used where more accurate timing is required (a Pyro musical or competition).


Shell linking using PIC Green –



Twist the PIC relative to the shell leaders’ placement (which gives the delay between each shell time over distance) then place in the leader and tape over the end to make watertight and secure. Or fold the match strands over the PIC and tape as in the picture above.

Quick Match to PIC -



To link Quick Match to PIC match you MUST strip the plastic coating off to ensure that the quick burning characteristics of the Quickmatch do not go out before lighting the PIC, removing the cover makes it more sensitive to heat/fire in order to transmit the burning successfully.

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