METHOD OF AND APPARATUS FOR PREVENTING OR DIMINISHING THE DESTRUCTIVE EFFECT OF FIRE AND EXPLOSION IN FLOUR MILLS AND FOR PURIFYING THE AIR WITHIN THE SAME, ALSO PARTLY APPLICABLE TO OTHER MILLS
Year: 1878

page_text: PROVISIONAL SPECIFICATION left by William Swain at the Office of the
Commissioners of Patents on the 6th November 1878,
"AN IMPROVED
WILLIAM SWAIN, of Newport Pratt, County Mayo, Ireland.
METHOD OF AND APPARATUS FOR PREVENTING OR DIMINISHING THE DESTRUCTIVE
EFFECT OF FIRE AND EXPLOSION IN FLOUR MILLS AND FOR PURIFYING THE AIR
WITHIN THE SAME, ALSO PARTLY APPLICABLE TO OTHER MILLS."
My Invention relates to an improved method of and apparatus for preventing or
diminishing the destructive effect of fires and explosions in flour mills, and for
purifying the air within the same, the said Invention being also partly applicable
to other mills, and it consists chiefly in providing improved means for extracting
or drawing off from the mill the heated air and particles of dust, flour, and other
light matters continually floating in the atmosphere within such mills when the
machinery is in motion.
The chief object of the said Invention is to prevent or mitigate the disastrous
effects of fire and explosion caused by the accumulation of air and dust and other
matters, which are but imperfectly removed by any of the methods or apparatus
heretofore employed.
Another object of the said Invention is to provide means for purifying the air in
such mills, so that the health of persons employed therein may not be so
endangered as it is when the hot air, dust, and floating particles of flour and the like
are allowed to remain, or are but imperfectly drawn away.
It is customary to employ in most flour mills an exhaust fan which draws the
heated air from the mill-stones, and with the current a great deal of dust is
conveyed up the spouts provided for the purpose until it reaches the fan. The fan
is generally so arranged, that it draws within itself the mingled hot air and dust,
and then blows it all out into a place provided for the purpose, generally called a
"stive room," in which room provision is made for disposing of the heated air
freed from the dust, flour, and other matters, an ordinary arrangement being to
place around the room frames covered with some woollen material, such as serge,
I Varios d

page_text: bunting, or the like through which the hot air escapes, and by a suitable channel
-is-conveyed to the outer atmosphere, leaving the dust and other matters with
which it was charged behind in the "stive room.
So far as I know it has always been the custom to effect the said operation
entirely within the mill itself, the air being discharged from the same through
the roof or walls after it has been drawn, to the stive room, and there separated
from the dust and other matters.
It is well known that mills provided with apparatus as above described or
similar thereto have frequently caught fire, under circumstances which leave but
little doubt in the minds of persons capable of forming an opinion on the subject
that the fire has resulted entirely from the accumulation and-concentration of
heated air charged with dust and other light floating matters. In many cases the
destruction has been so sudden and rapid that the mills may be said to have
actually exploded.
.
According to my said Invention, I place the exhausting fan and the apparatus
for separating the air and dust and other matters entirely outside the walls of the
mill, and I arrange pipes, tubes, or flues through which the air mingled with dust
and other light substances is drawn out of the mill to a suitable shed or other
structure, in which the dust and air are separated and the latter discharged into
the atmosphere, the dust and other matters being separated from the air before
the latter reaches the fan.
By means of this arrangement the danger of fire or explosion from the cause
herein before mentioned is reduced to a minimum, and if in any case a fire should
occur it would not be so destructive in its effects as such fires now are, as it would
. in all probability be confined to the outside shed, which could be readily replaced
without a large cost.
In carrying my said Invention into practice, I construct at any convenient place
outside the mill a shed or similar building of suitable size according to the size of
the mill in connection with which it is to be employed, or I may if desirable have
more than one shed. This shed or similar building should be constructed of non-
inflammable materials, such as bricks, or of wood or other substance rendered non-
inflammable by the application of a coating of asbestos or the like, and the walls of
this structure should be made as thin and slight as is consistent with sufficient
strength to support the roof and to stand firmly, for the reason that if it should be
destroyed by fire the loss would be insignificant. In the case of mills not provided
with convenient ground space outside the same, I may employ piles or pillars at a
suitable height from the ground, and upon which the shed will be supported. The
latter may in some cases be placed on piles or pillars above the roof of the mill, or
in any place which may be found most convenient for any particular mill to which
my Invention may be applied.
The said separate shed or building may be situated at a considerable distance
from the mill if convenient or desirable in any particular case, a suitable air passage,
pipe, or flue being provided to connect the mill with the shed, which passage, pipe,
or flue may be entirely underground if desired.
I prefer that the said shed or outside structure should be placed at as low a level
as is practicable, and that the pipes, passages, or other connections leading from the
mill to the shed should incline at an angle downward from the mill.
I provide pipes or tubes leading from the stones and from any part of the mill or
apparatus therein where heated air and dust are most likely to accumulate, such for
instance as the middlings, purifiers, and the elevators. These pipes or tubes should
be carried to the wall and out through the same by the nearest practicable route,
and they may all be continued direct to the aforesaid outside shed separately, or
may be made to unite in one larger tube or shoot leading to the shed. I prefer
that the tube in connection with the elevators should be placed on that side of the
latter which carries up the meal, flour, grain, or the like. By thus carrying off the
current the upward draught which travels along most elevators and which in the
case of fire assists the same is counteracted, and a. downward current is created

page_text: which is led by the pipes or tubes to the outside of the mill. If desirable, the said
pipes or tubes may be provided with suitable check valves or devices to prevent
any chance of fire being communicated to the mill along the said pipes or tubes in
the event of an explosion taking place in the shed or outside structure.
I also propose in some cases to provide a valve or valves in the pipe or pipes
outside the mill to admit fresh air therein, and mingle, with the air and dust going.
to the shed, this fresh air rendering the mixture of air and dust from the mill
less dangerous.
Within the said shed or outside structure I provide a cylinder or drum to which
the pipes or tubes coming from the mill lead. This cylinder is constructed with a
covering of some suitable material for arresting the particles of dust whilst the air
may pass through the same, and I propose to use for this purpose wire-gauze under-
neath flannel, serge, or similar material, or the wire ganze may be dispensed with if
desirable and only the flannel or similar material be used. The air cannot enter
the cylinder except through the said covering, the ends of the cylinder being
provided with air-partitions or leather curtains which prevent the air from entering
at those parts.
I place at a suitable distance beyond the said drum or cylinder a suction or
exhaust fan, by means of which the air, dust, and the like are drawn or exhausted
from the mill along the pipes, tubes, or other channels provided for the purpose,
The fan and cylinder may be operated in any suitable manner by means of a
strap or band leading from the mill, and driven by the steam or other motor
used in the mill, or if more convenient by a separate motor provided for the
purpose.
The said fan having been put in motion a strong draught is created in all the
pipes or tubes, which draught collects and draws with it the air, dust, and other
light floating particles within its reach, and conveys them to the outer circum-
ference of the aforesaid cylinder. The dust and other floating particles are here
obstructed whilst the air freed from the same is drawn into the cylinder, whence it
goes on to the fan and is blown out or discharged into the atmosphere outside the
shed. The cylinder or drum is caused to rotate slowly, and I provide at one or
more parts of its periphery a brush or a leather flap or both for the purpose of
ensuring the falling of the dust or other matters which may collect on the surface
of the cylinder. The said brushes may be caused to rotate or they may be
stationary.
If desirable the air and dust as it comes from the mill may be caused to enter
the interior of the cylinder and the air be drawn through the covering to the
outside, the dust and such particles being then collected within the said cylinder;
but I prefer that the air and dust should arrive outside the cylinder as first herein
described.
Any ordinary fan suitable for the purpose may be used, but care should be taken
to have it large enough and that it is not driven at too high a speed.
Although I consider it to be very advantageous to cause the heated air to be
filtered or separated from the dust and other light matters before it reaches the fan
as above described, I may if desirable in any particular case cause the said filtration
or separation to be effected afterwards as usually practised, but by means of the
cylinder herein before described.
It may sometimes be necessary or desirable to provide more than one cylinder
and more than one fan for each mill, and these may be placed in the same or in
separate sheds, and I may sometimes employ an intermediate fan or exhauster at
some part of the pipe leading from the mill to create a stronger draught.
The cylinder above described may be used with advantage even within a mill
for separating the air and dust in place of the woollen-covered frames above named.
In order to provide additional security against fire and explosion in flour and
other mills, I propose to light the same when working at night or at anytime
when artificial light is necessary from the outside by means of lamps placed outside
the windows. These may be gas, parafine, or other lamps, and should be furnished

page_text: with powerful reflectors to reflect the light to the interior of the mill, or the electric
light-may-be-used for the purpose of such exterior lighting.
I also propose in some instances to provide footways or balconies outside-the-mill,
which may extend partially or the whole way around the latter, and there may be
one or more of such footways or balconies, by means of which the miller or
attendant may walk around the exterior of the mill walls to inspect the pipes or
tubes, and light and attend to the lamps when lamps are used.