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

Steel Can Be Worked Cold
As noted above, steel can be worked cold, as in the case of ...

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

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

Effect Of Different Carburizing Material
[Illustrations: FIGS. 33 to 37.] Each of these different p...

Quenching
It is considered good practice to quench alloy steels from th...

Annealing
There is no mystery or secret about the proper annealing of d...

Heat-treating Department
The heat-treating department occupies an L-shaped building. ...

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

Quenching The Work
In some operations case-hardened work is quenched from the bo...

Judging The Heat Of Steel
While the use of a pyrometer is of course the only way to hav...

Process Of Carburizing
Carburizing imparts a shell of high-carbon content to a low-...

Tempering Colors On Carbon Steels
Opinions differ as to the temperature which is indicated by t...

Alloying Elements
Commercial steels of even the simplest types are therefore p...

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

The Effect
The heating at 1,600 deg.F. gives the first heat treatment w...

Hints For Tool Steel Users
Do not hesitate to ask for information from the maker as to t...

The Quenching Tank
The quenching tank is an important feature of apparatus in c...

Crankshaft
The crankshaft was the most highly stressed part of the entir...

Affinity Of Nickel Steel For Carbon
The carbon- and nickel-steel gears are carburized separately...



Complete Calibration Of Pyrometers






Category: PYROMETRY AND PYROMETERS

For the complete calibration
of a thermo-couple of unknown electromotive force, the new couple
may be checked against a standard instrument, placing the two bare
couples side by side in a suitable tube and taking frequent readings
over the range of temperatures desired.

If only one instrument, such as a millivoltmeter, is available,
and there is no standard couple at hand, the new couple may be
calibrated over a wide range of temperatures by the use of the following
standards:

Water, boiling point 212 deg.F.
Tin, under charcoal, freezing point 450 deg.F.
Lead, under charcoal, freezing point 621 deg.F.
Zinc, under charcoal, freezing point 786 deg.F.
Sulphur, boiling point 832 deg.F.
Aluminum, under charcoal, freezing point 1,216 deg.F.
Sodium chloride (salt), freezing point 1,474 deg.F.
Potassium sulphate, freezing point 1,958 deg.F.

A good practice is to make one pyrometer a standard; calibrate it
frequently by the melting-point-of-salt method, and each morning
check up every pyrometer in the works with the standard, making the
necessary corrections to be used for the day's work. By pursuing
this course systematically, the improved quality of the product
will much more than compensate for the extra work.

The purity of the substance affects its freezing or melting point.
The melting point of common salt is given in one widely used handbook
at 1,421 deg.F., although chemically pure sodium chloride melts at
1,474 deg.F. as shown above. A sufficient quantity for an extended
period should be secured. Test the melting point with a pyrometer
of known accuracy. Knowing this temperature it will be easy to
calibrate other pyrometers.





Next: Placing Of Pyrometers

Previous: Calibration Of Pyrometer With Common Salt



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