Monday, July 28, 2008

Firework Types, Explosives & How They Work Part 2

Set Pieces

These fireworks are, as their name suggests, used to create a static effect. They can be in the form of waterfalls strung horizontally on string or poles, wheels, flying pigs, fountains or lancework e.g. “Good Night”. These are mini flares linked together with fuse and burn for about 60 secs.

Careful attention needs to be paid to setting these up in order to gain the maximum effect from them, especially with respect to their height. Care must be taken to ensure that the moving fireworks set off in the right direction initially.

Most set pieces are not dangerous if properly assembled, however keep these out of the firing line to avoid premature ignition. Especially lance-work which must be set up-wind of the rest.

Lancework is a set piece of a special type. They are made up from small fireworks set on a frame which burn simultaneously as individual points of light to present a continuing two-dimensional picture. The picture may bes symbolic, such as a badge or crest, or in word form, such as “Good Night”.

More complex effects can be produced by creating different pictures in sequence on the same frame, to produce an impression of motion.

Explosives – How they work

Explosives can be classified under three headings:-

Deflagatory explosives (sometimes called low explosives), of which black powder is a typical example, are a mixture of a fuel and an oxidising agent.

On ignition, rapid combustion takes place producing quantities of hot gas. It is the expansive properties of this hot gas that, if suitably contained, gives rise to any explosive force produced. Deflagatory explosives form the vast majority of pyrotechnics mixtures.

By adjusting grain size and degree of compression of the powder before it is burnt, a considerable range of burn rates can be achieved. By the degree of containment of the hot gases after combustion has started, a considerable range of explosives force can be attained.

Hence the same quantity of black powder can be used to make a Gerb lasting 25 seconds or a lift charge for a shell fired from a mortar that burns for 6 micro seconds.

Because deflagatory explosives contain both fuel and oxidising agent, once alight they cannot be extinguished by blanketing with foam, Co2 etc. The best solution is to try to get sufficient water onto the fire to reduce the temperature to below the ignition point.

Caution! If however the fuel is metallic e.g. Magnesium, the application of water will have the same effect as squirting a bonfire with liquid oxygen! Magnesium is a very powerful reducing agent and can easily extract oxygen from substances commonly used in fire extinguishers e.g. water, carbon dioxide and even sand.

Fires involving pyrotechnic mixtures containing metallic fuels, are best covered with DRY sand in vast quantities in the hope that the thermal mass of the cold sand will cool the fire to below ignition temperature and before the metal fuel has had a chance to extract the oxygen from the sand.

It is also worth noting that pyrotechnic mixtures containing Aluminium and a nitrate oxidiser (e.g. Potassium Nitrate) will spontaneously ignite and then explode if they get wet.

Tuesday, July 22, 2008

Firework Types & How They Work

Roman Candles

A more complex firework, consisting of a tube containing pyrotechnic units alternating with propellant charges. When fired, the units are thrown into the air in sequence from top to bottom. Different effects are obtained by using successive units of varying colour and form. Roman Candles may also produce sound effects during their trajectory, including a report at the end. Between successive projections, the candle may emit coloured sparks or flame directly from the body.

They are made up to 60mm calibre and can send stars up to nearly 200 ft. The candle must therefore be securely fastened to a stake or candle frame.

It should be noted that as each successive star has further to travel up the case of the candle, it takes longer to exit the tube and is therefore subjected to the lifting charge for longer. The quantity of gunpowder has to be progressively decreased to achieve the same height. Do not use damaged candles – there could be a blow out.

Whilst the styles or effects have remained more or less unaltered throughout their history, there have been alterations in the method of activity of achieving the delay between the successive stars.

a) The original Ruggieri design utilised green mix gunpowder and these candles will emit showers of sparks between successive stars. It should be noted that with the exception of any tube products that may be used, all the products are consumed and there is little or no fallout.

b) Typical Chinese candles are used in vast quantities in the fireworks industry. Here a continuous fuse runs down the side of the tube and is designed to burn for the duration of the candle. The delay between successive stars is achieved by alternating them with loose plugs of potters clay. During the course of even a modest display, a considerable amount of clay is thrown into the air. Beware!

c) In recent Years Britannia Fireworks Ltd have been using “Typical” Chinese Candles manufactured using similar ideas to the “Ruggieri Technique”, and showers are emitted between each shot, this has enabled slightly better timing and larger stars etc.

d) To overcome the problems of achieving synchronised firing, there have been two developments, the earliest being the substitution of the green mix delay with a felt plug with a pressed delay in the centre. These felt plugs return to Earth unburnt.


A shell is a hollow projectile containing an explosive charge. In Western Europe and the USA the shell may also have an attached lifting charge. It must be remembered that this practice is by no means universal and the presence of a lifting charge would not be considered a defining characteristic by firework technicians. (The presence of a propellant charge is considered a defining characteristic of a rocket!)

The shell is projected from a mortar tube by a charge of gunpowder (the lifting charge) to burst high in the air with whatever effect is incorporated in the shell.

The mortar tube may be made from cardboard, fibreboard or specific types of plastic.

The shells may be made from paper or plastic and are either spherical or cylindrical in shape. It is much easier to contrive multiple breaks or bursts with a cylindrical shell, whereas the spherical shells are required to produce spherical bursts, chrysanthemums, peonies.

Shells which explode with a loud report are called maroons or salutes

The diameter of shells used at Britannia Fireworks Ltd are generally anything from 2” to 12” and come in two types:-

a) Bottom fused and

b) Top fused

Bottom fused shells have their lifting charge ignited first. This in turn ignites a delay fuse to the bursting charge.

Top fused shells are fitted with a delay fuse to the bursting charge with a secondary instantaneous fuse to the lifting charge. These are perhaps a little more reliable as there is less risk of the delay fuse being blown out. These tend to be more cylindrical in shape. Care must be taken when installing top fused shells to avoid damage to this lifting charge fuse. It is also essential to ensure that the shell, as with all shells, is inserted into the tube the right way up. Damaged shells should not be used.

Shells can be extremely dangerous if they are not handled and fired in the approved manner. The exit velocity of a shell from the mortar tube could be in excess of 200 mph!

To appreciate the height and effect of a shell, the following can be used as a rough guide

If ‘x’ is the calibre of the shell in inches,

the delay to full height is ‘x’ seconds,

the height reached is ‘X’ x 100 feet,

the spread of burst is ‘X’ x 10 metres.

This will not always apply, however it can be used as a guide for most shells.


These can be regarded as similar to shells in the method of use. The important distinction between them is that the firework element is ignited in the tube and is already burning when it exits the tube.

The effect of a mine is therefore instantaneous from the spectators viewpoint and always lower, although heights of 100 ft. may still be reached. These produce effects of stars, bombettes, whistles etc. Special care must be given when loading the bag type mines.

It is sometimes extremely difficult to distinguish the difference between some cylindrical mines and cylindrical shells and there are even some spherical mines.

Multi Shot Barrages or “Cakes”

These fireworks known affectionately as “cakes” are actually a collection of other categories of fireworks grouped together in boxes and produce stars, bombettes, whistles, spinners, etc. They may vary in size from small packages up to large cardboard boxes which can be very heavy to handle.

A cake barrage may contain anything from say 36 x 2.5”” shells in light tubes, 100 x 30mm maroons or even up to 1000 roman candles one shot in each tube.

They are extremely powerful so please be careful! They need to be set up very carefully, with particular attention paid to the surface upon which they stand and secured to a series of stakes. Cakes should always be angled away from spectators.

It is important to ensure that they are the right way up! It is not unknown for them to be labelled upside down or even the larger ones to be packed into their boxes upside down. Please take note !

Due to the size of some Cakes and the calibres used, we recommend moving them at least 50 metres, and in some cases even further (refer to Britannia Fireworks Site Policy)

Cake barrages are boxes containing a number of separate items, fused together so that they are fired in sequence over some period of time, normally much longer than for a single firework. The items may be all of one kind, or a mixture, including small, shells, candles etc.

As with roman candles, once started, the firing continues automatically until the last item is reached.

Batteries are comprised of a number of fireworks, normally of the same type, grouped in a single layout, to be fired as a single unit, individually in sequence, or in any other combination. The effect is the same as from any one firework on its own, enhanced by sequential or multiple firing.

Thursday, July 3, 2008

Basic Fireworks Training Course


This is to ensure that Display Firers have a full understanding of these general areas-

· Background law covering the storage, transport, and use of fireworks, and the difficulties & responsibilities involved in the operation of a fireworks display

· Communication before the display with other parties

· What makes a suitable fireworks display site, including surrounding areas

· Transport of materials to the site, in safety and in compliance with regulations

· Practical aspects of setting up the fireworks display safely.

· Safe firing of the display, including spectator management

· Complete clearance of the site after the display, leaving it tidy and safe for the public


Delegates will be taught the theory behind the safe use of fireworks and will also receive lessons of a practical nature in the tasks associated with setting up safe firework displays in order the work towards BPA Exam Level 1.

The second phase will be a further training period with the delegate attending shows with Britannia Fireworks & Events , to ascertain his/her level of competence. Further to this various tasks will be given, educating and increasing the level of skill as the trainee works through to Level two of the training Scheme. The number of shows will be dependent upon previous experience held by the delegate (minimum 12 shows from level 1), as they will have to demonstrate that they are familiar with all aspects of setting up and firing a display


The principal aim behind the course will be safety, particularly with the safety of the public and spectators in mind. Also, that it covers all the responsibilities associated with the display, not only the “Firework” element of the display, but also other activities involved in organising the whole event etc… We feel that this is not only beneficial in terms of additional knowledge, and the possible involvement with crowd control and similar aspects, but also in communicating and understanding successfully the needs of our clients etc..


These are key background Regulations affecting the manufacture, supply, and use of fireworks, and the operation of displays. Fireworks are exempt from some of the regulations concerned with explosives, but are mentioned in passing so that Firers are at least aware of their existence and associated responsibilities. We shall also cover the basic principles of explosives in general

If you are interested in attending a Fireworks Training Course then please contact our team at Britannia Fireworks & Events