Blasting machine
Blasting machines are devices for triggering electrical detonators in commercial and military explosives technology or bridge detonators in the pyrotechnics are used. More complex installations for the ignition are called ignition systems .
Blasting machines
The main operating principles are as follows:
- Generator blasters
- Capacitor blasters
- Ignition hose blasters
Generator blasters
With them, the electrical impulse (energy per unit of time) is generated by means of a sufficiently fast generator rotation. Mainly two mechanisms are used:
- In the spring-loaded generator blasting machines ( e.g. AEG, Bosch, Siemens), a spring is tensioned and mechanically secured using muscle power. When releasing the tensioned spring, i.e. for ignition, the stored force acts via a gear on the generator, which thereby supplies a sufficient current pulse.
- The most famous blasting machine is the so-called rack and pinion blasting machine (e.g. Siemens, ZEB Zünderwerke Ernst Brün GmbH, Schaffler, Styr). With her, the generator is moved directly by muscle power by quickly pressing down a rack .
Generator blasting machines have not been approved for blasting work in Germany for decades. Except for the ignition of small pyrotechnics , they are only important in collectors' circles.
The cube-shaped box made of dark bakelite with protruding T-shaped slide handle and running away ignition cable is a common icon for detonation in comics .
Capacitor blasters
The capacitor ignition machine (e.g. from ZEB, VEB-REMA, Schaffler) is the most widely used ignition machine for triggering electrical detonators. It essentially consists of a generator, a capacitor and the release device. If the generator is operated using muscle power, the energy generated is fed to the capacitor and stored there. For ignition, the charged capacitor is switched into the ignition circuit via the release device (e.g. push button).
Ignition hose blasters
In contrast to the above-mentioned blasting machines, the blasting hose blasting machine does not provide an electrical pulse, but a sufficiently strong arc (or spark, which can be generated, for example, by triggering a primer ). The shock wave of the arc (which is generated by the suddenly released heat in the air in the arc) initiates the layer of explosive vaporized in the shock hose. The way it works is closely based on the principle of a alarm gun or signal weapon. The latter are actually used in the police or military field for ignition hose ignition z. B. used as part of the doorway with small amounts of explosives.
Explosive technology ignition systems
The use of blasting machines is not appropriate where blasting takes place regularly at the same location, for example when driving tunnels in mining . For this reason, permanently installed ignition systems that can be approved by the appropriate bodies are used. These use mains electricity to detonate the explosive charges.
Pyrotechnic detonators
In the commercial application of large fireworks , electrical ignition has largely prevailed over pyrotechnic ignition (“enticing”, “manual ignition”). All effects are individually provided with bridge detonators and controlled by an ignition system with several ignition lines . The fireworks ignition systems are operated almost exclusively on the principle of capacitor ignition machines and supplied with direct current . Basically, the detonators of each ignition circuit are connected in series . The resulting high resistance of the series circuit due to the small cable cross-sections therefore require special attention to the voltage so that the necessary ignition current (minimum current strength for bridge igniter) is not undershot.
In practice there are two types:
- simple ignition systems in which each ignition line is triggered directly at the push of a button: This corresponds to a simple ignition device with channel selection. In practice, this means that the pyrotechnician sees little of his fireworks because he has to focus his attention on the timing and the predetermined ignition times (stopwatch necessary).
- Ignition computer that controls the ignition lines electronically. Precise time controls in the form of programming in the thousandth of a second range and complex time sequences are possible. The most modern systems can be programmed using a PC . This technology is almost indispensable for music-synchronized fireworks.
A distinction is also made between:
- Cable ignition , in which individual, two-wire cable strands are laid from the igniter to the ignition system directly or to another ignition module. When using ignition modules, the ignition system then transmits the ignition commands via a data cable , which are converted by the modules into low-voltage ignition pulses. The ignition modules are powered independently or in parallel with the data line.
- Radio ignition in which only radio modules are wired. These ignite by radio remote control with signals sent by the control ignitor. Larger spatial distances can be easily bridged here. Any susceptibility of the radio signal to interference and the high investment costs prove to be disadvantageous. Independent power supply of the modules is a prerequisite. The advantages are the possible use of water-bound launching points ( pontoons ) without a fireworker having to be in the burn-up zone, or in large building heights (roofing of football stadiums, bridges, house fronts). At the end of 2015, the state of the art is that the radio signals are transmitted on a reserved frequency and digitally coded. If a second radio system is operated locally on the same frequency, this is recognized and both systems block the triggering of ignitions.
All in all, due to the necessary power supply, especially at low winter temperatures and the susceptibility to moisture in other adverse weather conditions, blasting machines prove to be unreliable and require a good infrastructure at the firing range. In return, they opened up a multitude of effects that were previously barely reproducible (stepper effects every millisecond, effects from spatially distant positions simultaneously) and the musical fireworks led to a high level of synchronicity. All in all, ignition machine technology has made fireworks more attractive for the viewer, but has shifted the field of activity of the fireworks considerably from the classic manual work on black powder to dealing with line technology and programming .
Legal
Blasting machines of the blasting technology - regardless of the type - are blasting accessories within the meaning of the explosives law . As a result, they may only be used for commercial blasting work if they meet the requirements specified there. In addition to their general suitability as a blasting machine ( type test by an institution such as BAM ), in Germany they must also be subjected to a detailed test by a notified body (usually the manufacturer or a contractual partner), usually every two years .
Pyrotechnic ignition machines are freely available. Only their use with pyrotechnic objects is then subject to the relevant legal regulations (see pyrotechnics for details).
literature
- Horst Roschlau: Sprengen - theory and practice . Verlag für Grundstofftindustrie, Leipzig 1993, ISBN 3-342-00492-4 .
- for fireworks see the literature of the article fireworks
Web links
Individual evidence
- ↑ Pyrotechnics expert Christian Czech in: Moment am Sonntag: Heaven as a stage for stories made of light. Art and technology of fireworks. Barbara Zeithammer, ORF-Radio Ö1, December 27, 2015, 6:15 pm. http://oe1.orf.at .
- ↑ Explosive TR310. Federal Ministry of Labor and Social Affairs, October 5, 2016, accessed April 30, 2017 (German).