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Steel Making

Heat Treatment Of Gear Blanks
This section is based on a paper read before the American Gea...

Quenching The Work
In some operations case-hardened work is quenched from the bo...

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

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

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

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

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

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

The Theory Of Tempering
Steel that has been hardened is generally harder and more br...

Chromium
Chromium when alloyed with steel, has the characteristic func...

Annealing To Relieve Internal Stresses
Work quenched from a high temperature and not afterward tempe...

The Pyrometer And Its Use
In the heat treatment of steel, it has become absolutely nece...

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

Affinity Of Nickel Steel For Carbon
The carbon- and nickel-steel gears are carburized separately...

Leeds And Northrup Optical Pyrometer
The principles of this very popular method of measuring tempe...

Pyrometers For Molten Metal
Pyrometers for molten metal are connected to portable thermoc...

Carbon Tool Steel
Heat to a bright red, about 1,500 to 1,550 deg.F. Do not ham...

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

Manganese
MANGANESE is a metal much like iron. Its chemical symbol is M...

Correction By Zero Adjustment
Many pyrometers are supplied with a zero adjuster, by means ...



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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