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Steel Making

Impact Tests
Impact tests are of considerable importance as an indication ...

Carbon Steels For Different Tools
All users of tool steels should carefully study the different...

Sulphur
Sulphur is another impurity and high sulphur is even a greate...

Robert Mushet
Robert (Forester) Mushet (1811-1891), born in the Forest of D...

Heavy Forging Practice
In heavy forging practice where the metal is being worked at...

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

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. ...

Manganese
MANGANESE is a metal much like iron. Its chemical symbol is M...

Care In Annealing
Not only will benefits in machining be found by careful anne...

High Speed Steel
For centuries the secret art of making tool steel was handed ...

Sulphur
SULPHUR is another element (symbol S) which is always found i...

Preparing Parts For Local Case-hardening
At the works of the Dayton Engineering Laboratories Company, ...

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

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

Correction For Cold-junction Errors
The voltage generated by a thermo-couple of an electric pyrom...

Hardening Operation
Hardening a gear is accomplished as follows: The gear is tak...

The Pyrometer And Its Use
In the heat treatment of steel, it has become absolutely nece...

Air-hardening Steels
These steels are recommended for boring, turning and planing...

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



Compensating Leads






Category: PYROMETRY AND PYROMETERS

By the use of compensating leads, formed of
the same material as the thermo-couple, the cold junction can be
removed from the head of the thermo-couple to a point 10, 20 or 50
ft. distant from the furnace, where the temperature is reasonably
constant. Where greater accuracy is desired, a common method is
to drive a 2-in. pipe, with a pointed closed end, some 10 to 20
ft. into the ground, as shown in Fig. 128. The compensating leads
are joined to the copper leads, and the junction forced down to
the bottom of the pipe. The cold junction is now in the ground,
beneath the building, at a depth at which the temperature is very
constant, about 70 deg.F., throughout the year. This method will usually
control the cold-junction temperature within 5 deg.F.

Where the greatest accuracy is desired a compensating box will
overcome cold-junction errors entirely. It consists of a case enclosing
a lamp and thermostat, which can be adjusted to maintain any desired
temperature, from 50 to 150 deg.F. The compensating leads enter the box
and copper leads run from the compensating box to the instrument,
so that the cold junction is within the box. Figure 129 shows a
Brown compensating box.



If it is desired to maintain the cold junction at 100 deg.: the thermostat
is set at this point, and the lamp, being wired to the 110- or
220-volt lighting circuit, will light and heat the box until 100 deg.
is reached, when the thermostat will open the circuit and the light
is extinguished. The box will now cool down to 98 deg., when the circuit
is again closed, the lamp lights, the box heats up, and the operation
is repeated.





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Previous: Correction By Zero Adjustment



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