_______________________________________________________ | | | | | Size of Burner in | Candle-power | Candles | | Cubic Feet per Hour. | Developed. | per Cubic Foot. | |______________________|______________|_________________| | | | | | 0.5 | 18.0 | 35.9 | | 0.7 | 27.0 | 38.5 | | 1.0 | 45.6 | 45.6 | |______________________|______________|_________________| In the tabular statement in Chapter I. the 0.7-foot burner was taken as the standard, because, considering all things, it seems the best, to adopt for domestic purposes. The 1-foot burner is more economical when in the best condition, but requires a higher gas pressure, and is rather too powerful a unit light for good illuminating effect; the 0.5 burner naturally gives a better illuminating effect, but its economy is surpassed by the 0.7-foot burner, which is not too powerful for the human eye. For convenience of comparison, the illuminating powers and duties of the 0.5- and 0.7-foot acetylene burners may be given in different ways: ILLUMINATING POWER OF SELF-LUMINOUS ACETYLENE. _0.7-foot Burner._ | _Half-foot Burner._ | 1 litre = 1.36 candles. | 1 litre = 1.27 candles. 1 cubic foot = 38.5 candles. | 1 cubic foot = 35.9 candles. 1 candle = 0.736 litre. | 1 candle = 0.79 litre. 1 candle = 0.026 cubic foot. | 1 candle = 0.028 cubic foot. If the two streams of gas impinge at an angle of 90°, twin-injector burners for acetylene appear to work best when the gas enters them at a pressure of 2 to 2.5 inches; for a higher pressure the angle should be made a little acute. Large burners require to have a wider distance between the jets, to be supplied with acetylene at a higher pressure, and to be constructed with a smaller angle of impingement. Every burner, of whatever construction and size, must always be supplied with gas at its proper pressure; a pressure varying from time to time is fatal.