A pyranoscope is an instrument for displaying controlled large flames. The name pyranoscope stems from Greek, πῦρ "pyr" meaning "fire", Άνω "ano" meaning "sky" and σκοπεῖν, "skopeîn", "to look" or "see". The science of investigating the progression and propagation of flames using such an instrument is called pyranoscopy.
Design of pyranoscopes
In order to attain the proper and controlled combustion of the fuel, a pyranoscope's most important mission is to atomize the fuel rapidly and to ignite it reliably.
Unlike flame-throwers or flame projectors for stage use, the fuel of pyranoscopes has to be atomized before ignition. In contrast to flamethrowers a shoot of a pyranoscope only is possible vertically up (± 15°).
To meet the security policies of pyranoscopes the fuel and the oxidant (compressed air) should be separated as long as possible.
Pyranoscopes basically are technical implementations of fire-breathing.
The main components of pyranoscopes are: (from bottom to top)
Compressed air vessel
The air vessel should be amply dimensioned for one shoot. Its capacity is about ten times the volume of the fuel tank to allocate a complete combustion of the fuel.
The vessel should at least stand the double of the working pressure which is about 6 bar (90 psi).
The air connection should be secured by a non-return valve.
Main solenoid valve
It should have the same dimension like the fuel tank to enable an unrestricted air flow.
To trigger the pyranoscope this valve is opened for 0.5 seconds.
Normally the fuel tank of pyranoscopes is made of standard steel pipes in different lengths and diameters. Its diameter determines the size of the pyranoscope (½" to 2"). The length determines the volume and the amount of fuel for one shot.
The pipe has two extra connections on its lower side. One for filling and one for the level sensor. The filling pipe is attached to a small (⅛") solenoid valve. This keeps open until the level sensor sends its charged-signal. An external fuel pump provides the required fuel pressure of 2 bar (30 psi).
On top of the fuel tank, near to the atomized fuel-stream pyranoscopes a propane Gas burner is used as ignition unit. Its supply line should be made from flameproof materials. To prevent the ignition flame from being blown off by the fuel stream it must be well justified.
Larger pyranoscopes (≥ 1½") need an ignition booster for fail-safe operation. This is put into practice by a propane-buffer-pipe of 0.5 liters terminated with another ½" solenoid valve. A propane hit is blown in the ignition flame 0.1 seconds before opening the main valve.
To meet the safety guidelines of pyranoscopes it is very important to connect the compressed-air-plug first and give pressure to the vessel. This avoids fuel entering the vessel at any malfunctions or operation errors.