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Brown Automatic Signaling Pyrometer
In large heat-treating plants it has been customary to mainta...

Hardening High-speed Steel
In forging use coke for fuel in the forge. Heat steel slowly ...

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

Quenching Tool Steel
To secure proper hardness, the cooling of quenching of steel ...

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

Knowing What Takes Place
How are we to know if we have given a piece of steel the ver...

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

A combination of the characteristics of nickel and the charac...

Tensile Properties
Strength of a metal is usually expressed in the number of pou...

For Milling Cutters And Formed Tools
FORGING.--Forge as before.--ANNEALING.--Place the steel in a ...

Preventing Cracks In Hardening
The blacksmith in the small shop, where equipment is usually ...

Rate Of Cooling
At the option of the manufacturer, the above treatment of gea...

Annealing Alloy Steel
The term alloy steel, from the steel maker's point of view, r...

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

Steel Can Be Worked Cold
As noted above, steel can be worked cold, as in the case of ...

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

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

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

William Kelly's Air-boiling Process
An account of Bessemer's address to the British Association w...

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

Compensating Leads


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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