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Steel Making

Preventing Carburizing By Copper-plating
Copper-plating has been found effective and must have a thick...

Bessemer Process
The bessemer process consists of charging molten pig iron int...

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

Standard Analysis
The selection of a standard analysis by the manufacturer is t...

Hints For Tool Steel Users
Do not hesitate to ask for information from the maker as to t...

Ebbw Vale And The Bessemer Process
After his British Association address in August 1856, Besseme...

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...

Cutting-off Steel From Bar
To cut a piece from an annealed bar, cut off with a hack saw,...

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

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

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

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

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

Preventing Decarbonization Of Tool Steel
It is especially important to prevent decarbonization in such...

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

Properties Of Steel
Steels are known by certain tests. Early tests were more or l...

Carbon In Tool Steel
Carbon tool steel, or tool steel as it is commonly called, us...

Composition Of Transmission-gear Steel
If the nickel content of this steel is eliminated, and the pe...

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



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.





Next: Brown Automatic Signaling Pyrometer

Previous: Correction By Zero Adjustment



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