DUST EXPLOSIONS IN GRAIN SEPARATORS. 21 
frees the tripping mechanism, causing a hammer within the tank to 
strike a blow sufficient to break the bottle. The discharge of the 
sulphuric acid into the water containing soda causes the formation 
of carbon dioxide, which generates sufficient pressure to force the 
water through the discharge pipe and the nozzles to all the crevices 
of the separator. 
This extinguisher was designed in the Office of Put Roads and 
Rural Engineering, after the completion of the work in the field, 
by Elmer Johnson, assistant mechanical engineer, and J. C. Tae 
son, assistant agricultural engineer. A full-sized working model was 
constructed and has been tried out in the explosion galleries of the 
Bureau of Mines at Pittsburgh, Pa., and since that time on four 
different types of separators at the Arlington Experimental Farm. 
A total of 27 tests with this extinguisher have been made, and in no 
case did it fail to operate automatically and properly and to ex- 
tinguish the fire before any damage was done. 
The locations of the fuses F shown in the sketch are those suitable 
for the particular machine shown in the drawing. The locations, 
however, will vary with each machine, and must be selected so that 
the fuses are sure to be reached by the flame or the heat, but not so 
placed that the wire connecting them is likely to be broken by the 
straw or by the moving parts of the separator. 
The location of the nozzles depends upon the construction of the 
machine, but the following points should be observed : 
ee one nozzle directly above the cylinder, if possible; if eee 
place it so that the beater will pele diffuse the spray from that 
nozzle. 
Run the pipe line along aderneath the roof of the separator, with 
the nozzles pointing downward. 
Install a sufficient number of nozzles along this line, and so locate 
them that every chamber in the separator is thoroughly served by a 
nozzle. 
Particular pains should be taken to serve dead air spaces, as it is 
in these that dust is likely to accumulate. 
As the stacker end of the machine is less likely to contain any 
closed chambers, it is probable that, in most types of machines, the 
nozzles at.this ad may be 30 inches or more apart. 
The last nozzle along the pipe line and within the separator | shane 
be just above the end of the shakers. 
One nozzle may be located in the wind stacker by means of a flexi- 
ble connection from the pipe line. 
The tripping mechanism of this extinguisher is so arranged that 
it may be released by hand, and also arranged so that it can be 
locked while on the road. Two pounds pull is sufficient to release 
it, but it has proved to be sufficiently rigid to withstand the jar and 
