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Silicon
SILICON is a very widespread element (symbol Si), being an es...

Conclusions
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The Modern Hardening Room
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Case-hardening Treatments For Various Steels
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Making Steel Balls
Steel balls are made from rods or coils according to size, st...

Heat Treatment Of Gear Blanks
This section is based on a paper read before the American Gea...

Tempering Round Dies
A number of circular dies of carbon tool steel for use in too...

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

Preventing Cracks In Hardening
The blacksmith in the small shop, where equipment is usually ...

Application Of Liberty Engine Materials To The Automotive Industry
The success of the Liberty engine program was an engineer...

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

Mushet And Bessemer
That Mushet was "used" by Ebbw Vale against Bessemer is, perh...

Heat Treatment Of Lathe Planer And Similar Tools
FIRE.--For these tools a good fire is one made of hard foundr...

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

Separating The Work From The Compound
During the pulling of the heat, the pots are dumped upon a ca...

Correction By Zero Adjustment
Many pyrometers are supplied with a zero adjuster, by means ...

Instructions For Working High-speed Steel
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A Chromium-cobalt Steel
The Latrobe Steel Company make a high-speed steel without tun...

The Forging Of Steel
So much depends upon the forging of steel that this operation...

Plant For Forging Rifle Barrels
The forging of rifle barrels in large quantities and heat-tre...



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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