Spark-ignition

Recent developments in rotary atomization include the use of semiconductive composites (qv) for the rotary cup permitting the constmction of a unit that does not produce an ignition spark when brought close to a grounded workpiece yet has the transfer efficiencies associated with a rotary atomizer. In addition, the use of the semiconductive material softens the electrostatic field and results in less edge buildup and better penetration into recess areas. Other systems use electronic means to effectively prevent arcing to grounded surfaces. 

The control system must satisfy a set sequence, as is required by CEN or other standards. An air switch provides airflow to the unit. A 30-second purge of the unit takes place by the fan after this period, the ignition spark and pilot gas valve are operated. 

Maly, R. and Vogel, M., Initiation and propagation of flame fronts in lean CH4-air mixtures by the three modes of the ignition spark, Proc. Combust. Inst., 17, 821,1979. 

Hori, T., M. Shibata, S. Okabe, and K. Hashizume, Super Ignition Spark Plug with Fine Center Ground Electrodes. SAE, 2003-01-0404, 2003. 

The MIE of gas — air or vapour—air mixtures can be determined from the structural formula and the molar heat of combustion of the compounds studied, and equations for the calculation are presented. The method is stated to give more accurate results than conventional methods used to assess flammability of mixtures of gas or vapour with air [1], It is claimed that in oxygen MIEs are about a hundredfold lower than in air [2], A study of the ignition behaviour of dusts, including correlation of electrical and mechanical minimum ignition spark energies and ignition temperature is made [3],... 

It gets worse. The ignition spark does not occur at Top Dead Centre. If we assume that the spark is at 30 degrees after TDC, then only 5/6 of our lOmS is available for any useful burn. This means that we are looking at a burn period of some 8mS. 

Shimmering of hot gases in front of hot refractory may simulate flame Hot refractory background may cause flame simulation Electric ignition spark may simulate flame / ... 

In order to avoid including m the measurements of the speed of the flame any impetus that might be given by the igniting spark, the first screen-wire was fixed 40 cm. from the point of ignition. Other screen-wires were fixed 50,100, 200, 300, and 400 cm. respectively from the first. 

A very generalized principle of an intrinsically safe electric circuit is shown in Fig. 6.169. Power source, voltage and current limitation are located in a safe area or shall be explosion protected (e.g. in a flameproof enclosure) if located in a hazardous environment. The electric circuit entering the hazardous area as an intrinsically safe circuit is not capable of producing ignitable sparks at make or break. 

A finer control over the compression of the end gas in each cylinder is provided by either advancing or retarding the timing of the igniting spark. 

Some interesting delayed ignition sparks are produced with ferroaluminum (35 65) in simple rough powder formulations. These effects do not fit neatly in normal spark or glitter categories. 

In these tests any of the following is an indication of an ignition sparks, flash, snap, or smell of reaction products. 

The ignition spark spectra and the arc lines are easily distinguished. 15.3. Analytical Applications... 

Replace the ignition points and spark plugs time ignition (spark ignition). ... 

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