SMOKE FROM LOCOMOTIVES.

New Zealand Herald, Volume LXII, Issue 18949, 21 February 1925, Page 7

SMOKE FROM LOCOMOTIVES.

Sir, —"W.J.H." persists that the men employed on New Zealand locomotives are inefficient in that smoke is produced. The point is why the smoke from a locomotive cannot be completely consumed. Carbon in Newcastle coal will burn at about 650 to 700 deg. Fahr. The gases are roasted out at about 1800 deg. When mixed with air in suitable proportion these gases ignite at about 1900deg. In a welldraughted firebox the temperature in the centre of the fire is about 2200 deg.; along the sides and back the temperature is considerably lower, being in the neighbourhood of 1550 to 1850. That is why smoke cannot be entirely prevented. "W.J.H." speaks of expert naval liremen as being superior in firing efficiency to New Zealand railway employees. It is not so much the men but the boilers which aro ahead in efficiency. Only the most modern types of locomotive boilers are built with combustion chambers. In anv case, a marine fireman is not called upon to burn the same amount of coal oer square foot of grate as & locomotive man—not by a long way. "W.J.H." complains mostly of engines standing in the yard emitting smoke. In such circumstances it is not possible to raise the firebox temperature to complete igniting point ; hence the volume of smoke. If he were to observe a locomotive climbing a bank after having travelled several miles, he would see an appreciable reduction in smoke production. SIEAJt-GEXTER.