Protective Screens For Furnaces





Workmen needlessly exposed to the flames, heat and glare from furnaces

where high temperatures are maintained suffer in health as well as

in bodily discomfort. This shows several types of shields designed

for the maximum protection of the furnace worker.



Bad conditions are not necessary; in almost every case means of relief

can be found by one earnestly seeking them. The larger forge shops

have adopted flame shields for the majority of their furnaces. Years

ago the industrial furnaces (particularly of the oil-burning variety)

were without shields, but the later models are all shield-equipped.

These shields are adapted to all of the more modern, heat-treating

furnaces, as well as to those furnaces in use for working forges;

and attention should be paid to their use on the former type since

the heat-treating furnaces are constantly becoming more numerous

as manufacturers find need of them in the many phases of munitions

making or similar work.



The heat that the worker about these furnaces must face may be

divided in general into two classes: there is first that heat due

to the flame and hot gases that the blast in the furnaces forces

out onto a man's body and face. In the majority of furnaces this

is by far the most discomforting, and care must be taken to fend

it and turn it behind a suitable shield. The second class is the

radiant heat, discharged as light from the glowing interior of

the furnace. This is the lesser of the two evils so far as general

forging furnaces are concerned, but it becomes the predominating

feature in furnaces of large door area such as in the usual

case-hardening furnaces. Here the amount of heat discharged is

often almost unbearable even for a moment. This heat can be taken

care of by interposing suitable, opaque shields that will temporarily

absorb it without being destroyed by it, or becoming incandescent.

Should such shields be so constructed as to close off all of the

heat, it might be impossible to work around the furnace for the

removal of its contents, but they can be made movable, and in such

a manner as to shield the major portion of the worker's body.



First taking up the question of flame shields, the illustration,

Fig. 102, is a typical installation that shows the main features

for application to a forging machine or drop-hammer, oil-burning

furnace, or for an arched-over, coal furnace where the flame blows

out the front. This shield consists of a frame covered with sheet

metal and held by brackets about 6 in. in front of the furnace.

It will be noted that slotted holes make this frame adjustable

for height, and it should be lowered as far as possible when in

use, so that the work may just pass under it and into the furnace

openings.



Immediately below the furnace openings, and close to the furnace

frame will be noted a blast pipe carrying air from the forge-shop

fan. This has a row of small holes drilled in its upper side for

the entire length, and these direct a curtain of cold air vertically

across the furnace openings, forcing all of the flame, or a greater

portion of it, to rise behind the shield. Since the shield extends

above the furnace top there is no escape for this flame until it has

passed high enough to be of no further discomfort to the workman.



In this case fan-blast air is used for cooling, and this is cheaper

and more satisfactory because a great volume may be used. However,

where high-pressure air is used for atomizing the oil at the burner,

and nothing else is available, this may be employed--though naturally

a comparatively small pipe will be needed, in which minute holes

are drilled, else the volume of air used will be too great for

the compressor economically to supply. Steam may also be employed

for like service.




fronts.]



The latest shields of this type are all made double, as illustrated,

with an inner sheet of metal an inch or two inside of the front.

In the illustration, A, Fig. 102, this inner sheet is smaller,

but some are now built the same size as the front and bolted to

it with pipe spacers between. The advantage of the double sheet

is that the inner one bears the brunt of the flame, and, if needs

be, burns up before the outer; while, if due to a heavy fire it

should be heated red at any point, the outer sheet will still be

much cooler and act as an additional shield to the furnace man.





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