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Forging High-speed Steel
Heat very slowly and carefully to from 1,800 to 2,000 deg.F....

Pyrometers
Armor plate makers sometimes use the copper ball or Siemens' ...

The Care Of Carburizing Compounds
Of all the opportunities for practicing economy in the heat-t...

Bessemer Process
The bessemer process consists of charging molten pig iron int...

Annealing Of High-speed Steel
For annealing high-speed steel, some makers recommend using g...

Sulphur
SULPHUR is another element (symbol S) which is always found i...

Standard Analysis
The selection of a standard analysis by the manufacturer is t...

Refining The Grain
This is remedied by reheating the piece to a temperature slig...

Restoring Overheated Steel
The effect of heat treatment on overheated steel is shown gra...

Carburizing Material
The simplest carburizing substance is charcoal. It is also th...

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

S A E Heat Treatments
The Society of Automotive Engineers have adopted certain heat...

The Electric Process
The fourth method of manufacturing steel is by the electric f...

Silicon
Silicon prevents, to a large extent, defects such as gas bubb...

Effects Of Proper Annealing
Proper annealing of low-carbon steels causes a complete solu...

Hardening Carbon Steel For Tools
For years the toolmaker had full sway in regard to make of st...

Calibration Of Pyrometer With Common Salt
An easy and convenient method for standardization and one whi...

High-carbon Machinery Steel
The carbon content of this steel is above 30 points and is ha...

Drop Forging Dies
The kind of steel used in the die of course influences the he...

Testing And Inspection Of Heat Treatment
The hard parts of the gear must be so hard that a new mill f...



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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Previous: Leeds And Northrup Optical Pyrometer



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