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Uses Of The Various Tempers Of Carbon Tool Steel
DIE TEMPER.--No. 3: All kinds of dies for deep stamping, pres...

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

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

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

S A E Heat Treatments
The Society of Automotive Engineers have adopted certain heat...

Drop Forging Dies
The kind of steel used in the die of course influences the he...

Compensating Leads
By the use of compensating leads, formed of the same materia...

Hardening
The forgings can be hardened by cooling in still air or quen...

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

Fatigue Tests
It has been known for fifty years that a beam or rod would fa...

Steel Before The 1850's
In spite of a rapid increase in the use of machines and the ...

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

Detrimental Elements
Sulphur and phosphorus are two elements known to be detrimen...

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

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

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

Composition And Properties Of Steel
It is a remarkable fact that one can look through a dozen tex...

Air-hardening Steels
These steels are recommended for boring, turning and planing...

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

The Packing Department
In Fig. 56 is shown the packing pots where the work is packe...



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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