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Steel Making

The Effect
The heating at 1,600 deg.F. gives the first heat treatment w...

Tungsten
Tungsten, as an alloy in steel, has been known and used for a...

Molybdenum
Molybdenum steels have been made commercially for twenty-five...

Short Method Of Treatment
In the new method, the packed pots are run into the case-har...

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

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

Flange Shields For Furnaces
Such portable flame shields as the one illustrated in Fig. 1...

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

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

Lathe And Planer Tools
TO FORGE.--Gently warm the steel to remove any chill is parti...

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

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

Take Time For Hardening
Uneven heating and poor quenching has caused loss of many ve...

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

Shrinking And Enlarging Work
Steel can be shrunk or enlarged by proper heating and cooling...

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

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

Crankshaft
The crankshaft was the most highly stressed part of the entir...

Hardening
Steel is hardened by quenching from above the upper critical....

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



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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