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   Home - Steel Making - Categories - Manufacturing and the Economy of Machinery

Steel Making

Crucible Steel
Crucible steel is still made by melting material in a clay or...

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

Annealing In Bone
Steel and cast iron may both be annealed in granulated bone. ...

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

Vanadium has a very marked effect upon alloy steels rich in c...

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

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

Typical Oil-fired Furnaces
Several types of standard oil-fired furnaces are shown herew...

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

The Leeds And Northrup Potentiometer System
The potentiometer pyrometer system is both flexible and subst...

Tensile Properties
Strength of a metal is usually expressed in the number of pou...

Quality And Structure
The quality of high-speed steel is dependent to a very great ...

The forgings can be hardened by cooling in still air or quen...

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

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

Phosphorus is one of the impurities in steel, and it has been...

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

Complete Calibration Of Pyrometers
For the complete calibration of a thermo-couple of unknown e...

For Milling Cutters And Formed Tools
FORGING.--Forge as before.--ANNEALING.--Place the steel in a ...

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

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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