Excerpt from The Pentane Lamp as a Working Standard

Since all flames depend upon combustion it is to be expected that their intensity will vary with the proportion of oxygen and Of other constituents in the air supplied to the gaseous fuel of the flame. T O maintain a flame in a constant condition requires, therefore, not only uniform fuel, but also a uniform proportion Of oxygen in the air supplied to the flame. Good ventilation is con sequently desirable for all work with flames, and is indispensable where lamps Of other kinds are to be compared with a flame standard. The quantity Of air which must be supplied depends largely on the size and number Of flames in the room and also on the method of ventilating. The flames themselves set up currents of air, and if possible these currents should be utilized to remove immediately from the room all the vitiated air coming from the lamps. A hood placed above the photometer with a rising pipe to lead the warm air out of the room is most effective.

If the gases from the flames are allowed to diffuse into the room and are simply diluted by the air entering, a much larger amount Of fresh air will be needed. In such a case it has been estimated 5 that to keep the carbon dioxide content of the air down to 6 parts in 10 000, 3000 cubic feet of fresh air per hour must be supplied for each person in a room. A committee Of the American Gas Institute 6 has on this basis estimated that 36 900 cubic feet Of air per hour should be supplied for a photometer room where two persons work with a pentane lamp and a 5-foot gas flame, since in the production Of carbon dioxide the gas flame is approximately equivalent to six persons and the pentane lamp to four.

In a room where air enters at the bottom and escapes at or near the top the quantity estimated as above (about I 2 000 cubic feet per hour for a pentane lamp) is probably ample for any purpose, and if care is taken to allow direct escape Of the flame gases a much smaller amount is sufficient.

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