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

Tool Or Crucible Steel
Crucible steel can be annealed either in muffled furnace or b...

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

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

Uses Of The Various Tempers Of Carbon Tool Steel
DIE TEMPER.--No. 3: All kinds of dies for deep stamping, pres...

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

Fatigue Tests
It has been known for fifty years that a beam or rod would fa...

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

Case-hardening Treatments For Various Steels
Plain water, salt water and linseed oil are the three most co...

ANNEALING can be done by heating to temperatures ranging from...

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

Heat-treating Equipment And Methods For Mass Production
The heat-treating department of the Brown-Lipe-Chapin Company...

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

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

An Automatic Temperature Control Pyrometer
Automatic temperature control instruments are similar to the ...

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

Instructions For Working High-speed Steel
Owing to the wide variations in the composition of high-speed...

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

Piston Pin
The piston pin on an aviation engine must possess maximum res...

The Theory Of Tempering
Steel that has been hardened is generally harder and more br...

Complete Calibration Of 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

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.

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