The Barre daily times. (Barre, Vt.) 1897-1959, 1921-08-15
DUST EXPLOSIONS.
Faulty Electric Lamps Serious Men
ace, Says Expert.

| Faulty electrical installations anc
inadequate protection constitute a Sc
rious fire and dust explosion hazard il
dusty industries, say specialists of the
United States department of agricul
ture. To show that fire and explosions
may be caused by electric lamps, the
specialists conducted a series of exper.
| iments in the laboratories of a large
lamp manufacturing company.
All electric lamps in places where
explosive dusts are present should,
they say, be equipped with yaporproof
globes, protected by heavy guards to
prevent breakage. Many of the danger
Gus practices, such as the use OF open
wiring, drop cords, unprotected lights,
etc, can be eliminated by modern IN
stallaton methods. Explosions have
occurred as a result of lowering into
bin an unprotected electric light at
tached TO cord, say the experts. The
lamp may swing against the side of
the bin and if the globe is broken the
hot flament in the lamp is exposed
for an instant and the surrounding
dust cloud ignities.
ut is believed that any combustble
DUST continues on account of the ex-
periments, ''if allowed to collect on the
lamp in sufficiently thick layers and
remain long enough will ignite The
ignition of the dust is probably due to
the fact that the very chaffy dusts col
lect on the globe, where they form a
blanket which prevents radiation of
the heat generated in the lamp and
raises the temperature of the bulb to
the ignition temperature of the dust.
Some of the dust seems to melt or CON
geal and form on the globe a crust
which does not burn readily. During
the recent explosion prevention cam
paign about 20 cases were reported
where explosion or fire was supposed
to have been started by the ignition
OF dust which had settled on the lamp
or by the accidental breaking of the
electric lamp in dusty atmosphere
Under ordinary conditions, with the
small lamps commonly used in plants !
and with free circulation of air about |
the globe. it is believed unlikely that |
fire will start readily 1t is recon-
however, that all electric
lamps be equipped with vaporproof |
globes. The straight side vapofproof I
globe which prevents the accumulation
Of dust on the lamp be used to main
tain low temperature. The use of
drop cords and the so-called extension,
or portable, lamps il probably the
most common and Objectionable prac-
ice and should be eliminated so far as
possible.
In tests conducted at the Pitts
ourgh station of the bureau Of mines
/ 32-candle power electric lamp was
han 30 minutes the bulb had burst
md the coal dust was found to be on
ire. Following this experiment l6-
andle power electric lamp was placed
n a nail keg half filled with Pitts
,urgh coal dust. Eighteen minutes lat
II small puffs of smoke issued from
he keg and at the end of 80 minutes
he dust smoke steadily, continuing
o burn ever after the lamp had been
emoved. As a result of these tests il
vas concluded that possibly dust ex-
losions could be started by the break
az of an incandescent lamp in a dust I
loud or by the ignition OF dust which
ad settled on the lamp
Explosions were obtained with both h
acuum and gas-filled lamps. The only |
reception was with the vacuum tung-
ten and carbon lamps of very low
'attage. The failure to obtain an ex-
losion with them was due probably II
, the character of the dust cloud and H
he manner in which the lamps were
roken. Dust explosions and fires, II
1erefore, can be caused by the break Il
y of an electr bulb. II