METHODS FOR WORKING HOT BLAST STOVES. &£
by a fresh supply of oxygen or air and the heat of the oven. The chimney seen on top of the ovens at W creates a draft and permits the smoke or dead gas to escape. All the space about the pipes B and D is called the k' combustion chamber,'' and when the gas is burning in the oven this space area is filled with a flaming gas fire.
Should the furnace go out of blast for any reason to exceed two hours, the oven will generally cool down to such a degree as to be very liable to cause an explosion when the gas begins to enter. Again, the oven being cold, could not heat the blast at the start to any effective degree, and hence less iron would be produced, with a chance of also promoting " chilling " in the furnace. To prevent or guard against such ill results, a wood or coal fire is generally built in flues P by opening the doors V. By such a plan the heat of the oven can be maintained to 700 to 800 degrees. It is not infrequent that items are noticed in the trade and daily papers speaking of some furnace having had a gas explosion. A cold oven is often the cause, and furnacemen .watch this point very closely. Not only is it necessary that the ovens be hot when the gas from the ovens first enters them, biit it is also desirable that a flame be burning in the oven to insure the gas igniting. Some furnacemen will take no chances in this respect. If they shut down but for half an hour they will either have some dry wood or a few lumps of soft coal placed in the oven so as to insure a flame therein when the furnace begins to send its gas down the *l down-comer." A gas explosion can cause great damage, and the wise take no chances or risk with it.
The color of the gases escaping from the chimney or "slips" from the use of fine ores, etc. It may also beency :|,