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Steel Making

Manganese
Manganese adds considerably to the tensile strength of steel,...

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

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

William Kelly's Air-boiling Process
An account of Bessemer's address to the British Association w...

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

Brown Automatic Signaling Pyrometer
In large heat-treating plants it has been customary to mainta...

Optical System And Electrical Circuit Of The Leeds & Northrup Optical Pyrometer
For extremely high temperature, the optical pyrometer is lar...

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

Annealing Work
With the exception of several of the higher types of alloy s...

Heating
Although it is possible to work steels cold, to an extent de...

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

Steel For Chisels And Punches
The highest grades of carbon or tempering steels are to be re...

Annealing Of High-speed Steel
For annealing high-speed steel, some makers recommend using g...

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

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

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

Gas Consumption For Carburizing
Although the advantages offered by the gas-fired furnace for ...

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

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

Double Annealing
Water annealing consists in heating the piece, allowing it to...



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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