40 Farmers’ Bulletin 1285. 
An air-tight cleanout door should be installed at the junction of the 
flue and the smoke pipe. Care should be taken when connecting the 
flue with the furnace to see that all joints are air-tight. In plants 
of the double-cooker furnace type two flues, entering the same smoke 
pipe, are required and an air-tight damper should be installed in each 
flue, near the smoke pipe, so that only one furnace can be used, if 
desired, without draft interference from the other connection. 
The diameter of the smoke pipe should be 9 inches, 10 inches, and 
11 inches in plants of 150 to 300 gallons, 400 to 600 gallons, and 800 
gallons, respectively. The pipe should be rigidly supported and high 
enough to provide a good draft. It should be equipped with a 
damper placed in a convenient position. » 
AGITATORS. 
Agitation is considered absolutely necessary, both during cooking 
and while the concentrate is being drawn from the cooking tank. 
There is always a tendency of the suspended matter to settle and to 
form a more or less thick deposit in the bottom of the tank. This 
should be kept continually in motion, by hand or mechanical means, 
in order to insure a product of even quality and a minimum amount 
of sludge. This is especially necessary during the first half of the 
cooking period. 
Agitators vary in design according to the shape and type of tank 
in which they are to be used. The ty pe shown in Figures 9 and 24 
is extremely simple in design. It consists of two or three cast-iron, 
spiders (old pulleys may be used) and four pieces of flat iron. The 
spiders are mounted on a shaft running longitudinally through the 
cooking tank. The flat iron paddles are connected to each spider » 
and should be twisted so that, as the agitator revolves, they will cut 
through the heavy mass at an angle and, in disturbing it, tend to 
raise it into the less dense portion of the mixture. Suggested sizes 
of parts for agitators of this type are given in Table 2. There should 
be a clearance of 1 to 14 inches between the bottom of the tank and 
the agitator paddles when in their lowest position. 
If a circular cooking tank is used the shaft of the agitator should 
be installed in a vertical position and the agitator should be of a 
different design. A suitable one consists of a shaft of square iron 
to which are bolted several pieces of flat. bar iron as paddles. These 
should be bent slightly and the leading edge sharpened so as to cut 
the mass at an angle as the shaft revolves. 
The agitator should make about 60 revolutions per minute. The 
speed of a horizontal agitator will be governed by the speed of the 
engine that drives it, the diameter of the pulley on the engine shaft, 
and the diameter of the large pulley on the end of the agitator shaft, 
all of which must be correctly proportioned. If a vertical shaft 
agitator is used the shaft must be extended far enough upwards 
through a plank bolted to the top of the tank to allow for the neces- 
sary gearing. A bevel gear fitted to the shaft, the pinion engaging it 
and fitted to the end of a jack shaft, and a large pulley on the other 
end of the jack shaft must all be correctly proportioned to give the 
required speed of the paddles. 
Power for the agitator may be obtained from a 13 to 5 horsepower 
gasoline engine, depending upon the size of the plant, or from a 
