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Carburizing Low-carbon Sleeves
Low-carbon sleeves are carburized and pushed on malleable-ir...

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

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

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

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

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

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

Classifications Of Steel
Among makers and sellers, carbon tool-steels are classed by g...

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

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

A Satisfactory Luting Mixture
A mixture of fireclay and sand will be found very satisfactor...

Carburizing Material
The simplest carburizing substance is charcoal. It is also th...

Heat Treatment Of Axles
Parts of this general type should be heat-treated to show the...

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

Restoring Overheated Steel
The effect of heat treatment on overheated steel is shown gra...

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

The Quenching Tank
The quenching tank is an important feature of apparatus in c...

Effects Of Proper Annealing
Proper annealing of low-carbon steels causes a complete solu...

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

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



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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