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Effect Of A Small Amount Of Copper In Medium-carbon Steel
This shows the result of tests by C. R. Hayward and A. B. Joh...

Tool Or Crucible Steel
Crucible steel can be annealed either in muffled furnace or b...

Case-hardening Treatments For Various Steels
Plain water, salt water and linseed oil are the three most co...

Hardening High-speed Steels
We will now take up the matter of hardening high-speed steels...

The Forging Of Steel
So much depends upon the forging of steel that this operation...

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

Typical Oil-fired Furnaces
Several types of standard oil-fired furnaces are shown herew...

Oil-hardening Steel
Heat slowly and uniformly to 1,450 deg.F. and forge thorough...

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

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

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

Tempering Round Dies
A number of circular dies of carbon tool steel for use in too...

Pickling The Forgings
The forgings were then pickled in a hot solution of either ni...

Application Of Liberty Engine Materials To The Automotive Industry
The success of the Liberty engine program was an engineer...

The Effect Of Tempering On Water-quenched Gages
The following information has been supplied by Automatic and ...

Carburizing By Gas
The process of carburizing by gas, briefly mentioned on page ...

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

Heat-treating Department
The heat-treating department occupies an L-shaped building. ...

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

Phosphorus
PHOSPHORUS is an element (symbol P) which enters the metal fr...



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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