Pullman herald. [volume], July 19, 1918, Image 5

About Pullman herald. [volume] (Pullman, W.T. [Wash.]) 1888-1989

Image provided by: Washington State Library; Olympia, WA

                
PREVENTION OF AND PROTECTION FROM SMUT DUST
EXPLOSIONS AND FIRES IN GRAIN SEPARATORS
Bj
G. K. THORNTON
Department of Mechanic Arte ami (engineering
sMI DUST EXPLOSIONS AND KIRKS
File Protection
In order to protect the machine and threshed grain from destruction by
f irt a set of rules similar to the following should be made and strictly
eDfi° rC _.o not smoke around separator, straw stack or threshed .train
,' Keep all litter and straw cleaned up around the machine '
-• Pi )e the sacks of threshed grain far enough from the machine an.l
..raw stack so thai they will not be destroyed In case of fire
8 4. Plow a strip around the netting and around the Back pile to protect
,he shocked grain and the sacked grain. lv -,roiect
16. Provide your machine with a reliable sprinkler system, preferably
automatic. Inspect it each day and be sure thai it is In working order be
(ore starting up.
6 Have your machine wired to carry away accumulations of static
-■"•/•■lnstall a dust collecting apparatus on your machine:
7 Install a dust collecting apparatus on your machine-
It lessens the danger of explosions and fires.
The threshed grain sells higher on the market.
It provides better working conditions for men.
' 8i Fasten a half-inch steel cable to the front of ' the separator and the
front of the engine so that the separator may be pulled away from the straw
,tack in case of fire When a steam hose is used in connection with the
sprinkler system it should be long enough so thai it will not be pulled in
wo when the engine is backed up. lie sure that this cable is in place be
fore starting up.
■•. 9. See that spark hood on engine stack Is in good order and is In
place at each setting.
10. Instruct your men what to do in case of fire. Frequent fire drills
are recommended.
>V... Prevention of and Protection from Fires
For the past four years the question of smut dust explosions and fires
as applied to threshing machines in the wheat belt of the Northwest has
been studied by members of the experiment station staff and engineers of
the State College of Washington, the United States Department of Agri
culture at Washington, D. C, co-operating, '
A study of such fires and explosions convinced the investigators that
the explosions, with their subsequent fires, were caused by the ignition
0 a mixture of smut dust and air within the threshing machine which
explosion and fires might result from any one of the following 'causes,
to-wit: - '■*_.__
1. Incendiarism. • - J *-.-*.-*.
2. Spark or live coal from engine.
3. A hot bearing. .
4. Striking of cylinder teeth upon concave's. Gravel or small stones
passing through cylinder.
5. Static electricity.
Threshing machine operators report having found matches in the grain
shocks and in the- separator after a fire. In tests made with a machine
in Whitman County, Washington, matches tied up in the grain were fed
into the machine and in each case a fire resulted.
2, In some tests made by .Mr. Q. A. Olson, chemist at the State Col
lege of Washington, in 1914, upon the inflammability of a mixture of
smut dust and air it was determined that the liability of explosions from
8 spark or live coal were very remote. He found it impossible to ignite
such a mixture by inserting Into it a red hot piece of charcoal. A spark
from the engine or a live coal alighting in the straw or chaff about a
machine' might, however, cause an outside fire.
8. Fire-; caused by hot bearings are due to gross neglect on the part
of the"separator tender and need not be- discussed here.
4... If the teeth in the cylinder and concaves get loose or get out of
alignment and strike against each other they may possibly cause a spark
.[sufficient Intensity to ignite the dual mixture within Ihe machine
During the cleanup if small stones or gravel are allowed to pass through
the cylinder they also may strike against the teeth and cause a spark.
toe operators spread canvas aboul the separator and thereby, in clean
tat up, avoid danger from such rubbish.
The cylinder teeth should be frequently examined to see that they are
in the correct position and. if possible, a place should be chosen for a
set up which is free from rock and gravel.
_. Experimentation has established the fact thai smut dust may be
fired by static, electricity.
Static electricity is generated in a separator by the movement of grain
and straw across the various parts of the machine and by the moving
belts. This electricity accumulates until a sufficient potential is available
to cause it to jump to some other part of the machine which is at a lower
potential, lf this discharge lakes place In the proper mixture of smut and
air, an explosion will occur. In igniting the smut and dust particles with
it. the separator its action is the same as that of a spark within the
cylinder of a gas engine.
The only practical method of dealing with this discharge is to provide
an easy path by which the potentials within the machine are equalized
and the whole of the metal parts effectively grounded. This is most easily
accomplished by carefully connecting all of the metal parts to a com
mon collecting point which is, in turn, connected to the ground.
Prevention of Fires
Since no practical means have been developed for the elimination of all
the smut, the danger from fires is ever present and every possible means
should be used to prevent the explosions within the separator and the
fires outside of the machines.
The following points should be observed in regard to the condition
and care of the separator:
1. The litter which collects around the outside of the machine should
be cleaned up frequently.
2. The hearings should be inspected often and should be kept well
oiled bo that heating will be prevented.
3. Accumulations of dust collecting on the framework and top of the
separator should be swept down frequently.
4. If possible, pockets or ledges anywhere about the machine in which
there is a liability of dust collecting should be eliminated. Such dust
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ft"-wn about by an explosion pn ruel for the tiro thai ... ,
sid; of th?maSn"" kNO, Sr° K,V '"" '<• ItaSSfl oTeltho,
b€ .nsp., ..'; J 1.," ,";■ e"g,ne Bho,} ld »»*•» >>• In Place and should
\u „,*•, . , Ure wnre "° r"sl lu,l,'s ln •■■■' mrm_.
.... us .;:,"' h? maCh'ne ,hoU,d '"• connected to the .'.round by
es straw™ k ' I 1 T'-'"' Ui"'s sl ld '"' ""' 'ron. «,« shak
framl work '« ffii?" 9,,aft\, c >lmder uud beat« sl'*fts* "d metal
metal" mn,irito„"f. n-wire> Which ln turn slloUld be connected to a
Sf time, hi in • ,noi>\f ro,l»u' n>* dirt around this pin should at
around it be in n a mo,si condition and. li ..... dry, a pail of water poured
around it will insure a good contact with the ground
Do not depend upon a wire connected ... the bearings to take away the
u,',u"""un",;- '" -B-ectriclty. rhe oil riltn between Ih? shaft and ,*., ■
■»">..•■«;■■ ;' ver> mfectl Vf Insulation and the desired result may not be
obtained . A metal brush made frfani a thin strip of brass should be so
fastened o the bearing that it «ffi have a rubbing contact with the re
volrin, shaft. The brush should then be connected to the w-ire whS
leads to the ground. (See cut.)
The straw racks and shakers should he connected to the wiring system
by a flexible metal coil to allow free movement of the parts and vet. main
tain a good contact.
If a steel separator is used the different parts need only to be connected
to the metal frame work which in turn should be connected to the ground.
Exhaust Fans
Another method of preventing explosions and subsequent fires is to re
move the smut dust from the interior of the machine by means of a
suction fan. A fan of the type used on the- stackers is preferred because
such fans are not easily clogged with straw. This fan should be located
to the rear of the cylinder and as close to it as possible. The speed should
be as high as possible without pulling the grain and large particles of
straw into the fan. The intake should extend across the entire width of
the separator. The fan should be driven fi-om the beater shaft or from
some other convenient shaft.
It has been carefully determined that much of the' smut In wheat re
sults from inoculation of the summer fallowed ground during threshing
time. It would be desirable therefore to destroy the smut drawn off by
the exhaust fan; but no efficient and economical method has yet been
devised.
In providing a sprinkler system for the separator any one of the six
types given below may In* used,
Sprinkler Systems
1. Automatic system connected directly to the engine boiler.
2. Hand operated system connected to the engine boiler.
3. Tank, air pressure system mounted on a cart and independent of
the engine.
5. Automatic chemical extinguishers.
C. An independent water pump on the engine connected by a hose line
to the separator.
The most successful types have been those In which steam from the en
gine boiler was used. The steam smothers the fire and seems to act much
quicker than a water spray upon the dust which is held In suspension in
the air within the machine.
Automatic System. The automatic sprinkler is presented to machine
owners to meet the demand for a system which is automatic in its action
and at the same time very simple and economical of installation.
The system consists of four special nozzles, each eulpped with a sensi
tive fuse which melts at 160 degrees F. These nozzles are connected by
means of a suitable piping system and hose line directly to the boiler of
the engine. The connection from the boiler to the hose line should bo
made by inserting a tee with a hose connection and valve Into the blow
off pipe.
The nozzle is of a special type designed by C. E. Thornton of the
Mechanical Department of the State College and each one* is thoroughly
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tatted ... determine l\x ability .to stand up under holler pressures as high
euulnm* ,u '*d "" 3ft engtne "' Tll<l fuse with which the nossle is
2V_UU hia " fn-r£ C,?. n' Btren. B^ll " „' nßion "' *«■ " ■>"»• <>' 350 pounds
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J;,""" ?, !. '"' '" Bcrw, eJ Into « pipe line which runs outside
S Stsa" nttfJ !- '"" '" ''"" machine and when in »,lace they could
';"? "-?' * little below the inside of the top boards or metal top
? the , separator. The no._le should be turned so that the fuse will be
£r.^ ,e t "■■••>' o the mach,ue' In this position the straw will keep
the fuse bright ami free from dust and thus permit a quick action of tho
hi „! I'u", l. '"''' .v c wlli *)*,in' J o the straw will wear the fuse It should
be inspected every three or four days and "' the wear Is excessive the
use should be replaced by a new one. To make a replacement, loosen tho
machine screw .., the lower bar ... the nozzle two turns, slip on a new
fuse, tighten the crew and the nozzle is ready for use.
• it the automatic system ii used a tee with hose connection should be
inserted fl as the pipe line on the separator for ihm purpose of fighting
outside fires. -$.■"■■:-. *"s""u*
The advantage of this equipment is readily seen. Its action is instan
taneous. it la simple and economical of installation. Tho piping being
outside the machlneand nozzles projecting inside, there is nothing to col
lect straw or interfere with the passage of the straw over the straw racks.
ihe entire system can be assembled on the ground and fastened In place
on the top of the machine by ana of four pipe straps. (For description
of Automatic Sprinkler and method of Installation see Plate 1, at back of
bulletin i
Kami Operated Sprinkler System, The hand operated system Is nearly
the same as the automatic sprinkler. The difference Is In the nozzles and
method of working the valve at the engine for admission of steam to the
line leading to the separator.
Tank Air Pressure System Mounted on a Cart. Provide a two-wheeled
cart upon which can be mounted two forty-gallon tanks such as are used
on hot water systems in the homo. This cart should be trailed behind the
separator during the threshing season, and afterward should be stored In
an outbuilding ready for an.) emergency about the farm.
These tanks should be filled two-thirds full of clear water and then
pumped up with air until a pressure of 100 to 125 pounds is reached. An
automobile tire pump may be used for this purpose, A pressure guage
should be placed on the tanks for determining the amount of pressure.
The tanks should bo connected to a sprinkler system on the separator
by means of a %-inch hose The system may be ptit Into aclton by pulling
a rope which opens a valve In the* pipe line.
The nozzles used on such a system should be of a type which are not
easily clogged by dust from the outside of the pipe line or by sediment
on the inside. A very cheap and efficient nozzle may be made from a
■i-inch pipe cap, as shown by the print at the back of this bulletin.
Another non-clogging nozzle ma. be made from a cast iron pipe plug,
as described In Bulletin No. 379 of the United states Department of Agri
culture, Washington, D. C.
Smut Fans
The fire hazard may be greatly reduced by installing a suction fan on
the separator to remove the smut dust from the Interior of the machine.
The removal of the smut dust from the machine dilutes the mixture and
reduces the danger of an explosion. The' fan should be of the exhauster
type and should be designed for the removal of dust and fine particles of
straw.
For a 32-inch cylinder or smaller, a 12-inch fan is recommended. Over
that size, a 15-inch tan is recommended. The speed of such fans range
from 1200 to 1600 revolutions per minute.
The speed at which the fan should run can be determined by watching
its action. If it picks up large particles of straw and some of the lighter
kernels of grain, the speed la too high, If it is not convenient to change
the size of the drive pulley, a damper should be provided In the suction
p.p.' for throttling the intake. Although the latter method reduces the
efficiency of the fan, it is tin more convenient and provides a ready means
of adjust nt to suit the conditions under which the machine is operating
The elbow opening from the fan to the pipe carrying the smut away
should be made bo thai ii will swing to either side of the machine.
Such fans are built and put on the market by the Sturtevant Fan Com
pany of Seattle, Washington, and also by the American Blower Company
of Seattle, Washington.
If you need help in installing lire fighting apparatus upon your sep
arator write to The stale College of Washington Extension Service,
stating the make, model, and size of you separator and whether you are
using a steam or gas engine. A specialist has been detailed to this
work and will be glad to help in any way possible. He will be glad to
answer your letters and will be able to visit a considerable number of
machines and advise with owners concerning the placing of fire exten
guishers, smut fans, and the wiring of the separator to carry away static
electricity.
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