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Plant For Forging Rifle Barrels
The forging of rifle barrels in large quantities and heat-tre...

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

Process Of Carburizing
Carburizing imparts a shell of high-carbon content to a low-...

Effect Of Different Carburizing Material
[Illustrations: FIGS. 33 to 37.] Each of these different p...

Annealing In Bone
Steel and cast iron may both be annealed in granulated bone. ...

Carburizing Low-carbon Sleeves
Low-carbon sleeves are carburized and pushed on malleable-ir...

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

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

Protective Screens For Furnaces
Workmen needlessly exposed to the flames, heat and glare from...

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...

Effects Of Proper Annealing
Proper annealing of low-carbon steels causes a complete solu...

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

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

Chrome-nickel Steel
Forging heat of chrome-nickel steel depends very largely on ...

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

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

Phosphorus
Phosphorus is one of the impurities in steel, and it has been...

The Influence Of Size
The size of the piece influences the physical properties obta...

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



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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