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Steel Making

This steel like any other steel when distorted by cold worki...

Temperature Recording And Regulation
Each furnace is equipped with pyrometers, but the reading an...

Protective Screens For Furnaces
Workmen needlessly exposed to the flames, heat and glare from...

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

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

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

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

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

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

Carbon In Tool Steel
Carbon tool steel, or tool steel as it is commonly called, us...

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

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

Surface Carburizing
Carburizing, commonly called case-hardening, is the art of pr...

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

Non-shrinking Oil-hardening Steels
Certain steels have a very low rate of expansion and contract...

Knowing What Takes Place
How are we to know if we have given a piece of steel the ver...

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

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...

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

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.

Next: Placing Of Pyrometers

Previous: Calibration Of Pyrometer With Common Salt

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