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Composition And Properties Of Steel
It is a remarkable fact that one can look through a dozen tex...

Heat Treatment Of Axles
Parts of this general type should be heat-treated to show the...

Protectors For Thermo-couples
Thermo-couples must be protected from the danger of mechanica...

Brown Automatic Signaling Pyrometer
In large heat-treating plants it has been customary to mainta...

Chrome-nickel Steel
Forging heat of chrome-nickel steel depends very largely on ...

Heat Treatment Of Milling Cutters Drills Reamers Etc
THE FIRE.--Gas and electric furnaces designed for high heats ...

Optical System And Electrical Circuit Of The Leeds & Northrup Optical Pyrometer
For extremely high temperature, the optical pyrometer is lar...

Quenching Tool Steel
To secure proper hardness, the cooling of quenching of steel ...

Annealing Work
With the exception of several of the higher types of alloy s...

Cyanide Bath For Tool Steels
All high-carbon tool steels are heated in a cyanide bath. Wi...

Annealing Alloy Steel
The term alloy steel, from the steel maker's point of view, r...

Open Hearth Process
The open hearth furnace consists of a big brick room with a l...

Compensating Leads
By the use of compensating leads, formed of the same materia...

Machineability
Reheating for machine ability was done at 100 deg. less than ...

Conclusions
Martien was probably never a serious contender for the honor ...

Gears
The material used for all gears on the Liberty engine was sel...

Lathe And Planer Tools
FORGING.--Gently warm the steel to remove any chill, is parti...

Lathe And Planer Tools
TO FORGE.--Gently warm the steel to remove any chill is parti...

Pyrometers For Molten Metal
Pyrometers for molten metal are connected to portable thermoc...

Composition Of Transmission-gear Steel
If the nickel content of this steel is eliminated, and the pe...



Optical System And Electrical Circuit Of The Leeds & Northrup Optical Pyrometer






Category: PYROMETRY AND PYROMETERS

For extremely high temperature, the optical pyrometer is
largely used. This is a comparative method. By means of the rheostat
the current through the lamp is adjusted until the brightness of
the filament is just equal to the brightness of the image produced
by the lens L, Fig. 123, whereupon the filament blends with or
becomes indistinguishable in the background formed by the image
of the hot object. This adjustment can be made with great accuracy
and certainty, as the effect of radiation upon the eye varies some
twenty times faster than does the temperature at 1,600 deg.F., and some
fourteen times faster at 3,400 deg.F. When a balance has been obtained,
the observer notes the reading of the milliammeter. The temperature
corresponding to the current is then read from a calibration curve
supplied with the instrument.



As the intensity of the light emitted at the higher temperatures
becomes dazzling, it is found desirable to introduce a piece of red
glass in the eye piece at R. This also eliminates any question
of matching colors, or of the observer's ability to distinguish
colors. It is further of value in dealing with bodies which do
not radiate light of the same composition as that emitted by a
black body, since nevertheless the intensity of radiation of any
one color from such bodies increases progressively in a definite
manner as the temperature rises. The intensity of this one color
can therefore be used as a measure of temperature for the body
in question. Figures 124 to 126 show the way it is read.





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