Effect: A spectators card rises from the center to the top of the pack repeatedly. (As in the ambitious card). Then the performer places the card in the center of the pack once more, and the card jumps out of the pack and lands in the hand of the per... Read more of Very Ambitious Card at Card Trick.caInformational Site Network Informational
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Steel Making

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

Placing The Thermo-couples
The following illustrations from the Taylor Instrument Compan...

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

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

Forging High-speed Steel
Heat very slowly and carefully to from 1,800 to 2,000 deg.F....

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

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

Nickel
Nickel may be considered as the toughest among the non-rare a...

The Penetration Of Carbon
Carburized mild steel is used to a great extent in the manufa...

Heat Treatment Of Steel
Heat treatment consists in heating and cooling metal at defin...

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

Gears
The material used for all gears on the Liberty engine was sel...

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

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

The Leeds And Northrup Potentiometer System
The potentiometer pyrometer system is both flexible and subst...

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

Highly Stressed Parts
The highly stressed parts on the Liberty engine consisted of ...

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

Calibration Of Pyrometer With Common Salt
An easy and convenient method for standardization and one whi...

Suggestions For Handling High-speed Steels
The following suggestions for handling high-speed steels are ...



Calibration Of Pyrometer With Common Salt






Category: PYROMETRY AND PYROMETERS

An easy and convenient method for standardization and one which
does not necessitate the use of an expensive laboratory equipment
is that based upon determining the melting point of common table
salt (sodium chloride). While theoretically salt that is chemically
pure should be used (and this is neither expensive nor difficult
to procure), commercial accuracy may be obtained by using common
table salt such as is sold by every grocer. The salt is melted in
a clean crucible of fireclay, iron or nickel, either in a furnace
or over a forge-fire, and then further heated until a temperature
of about 1,600 to 1,650 deg.F. is attained. It is essential that this
crucible be clean because a slight admixture of a foreign substance
might noticeably change the melting point.

The thermo-couple to be calibrated is then removed from its protecting
tube and its hot end is immersed in the salt bath. When this end
has reached the temperature of the bath, the crucible is removed
from the source of heat and allowed to cool, and cooling readings
are then taken every 10 sec. on the milli-voltmeter or pyrometer. A
curve is then plotted by using time and temperature as cooerdinates,
and the temperature of the freezing point of salt, as indicated
by this particular thermocouple, is noted, i.e., at the point
where the temperature of the bath remains temporarily constant
while the salt is freezing. The length of time during which the
temperature is stationary depends on the size of the bath and the
rate of cooling, and is not a factor in the calibration. The melting
point of salt is 1,472 deg.F., and the needed correction for the instrument
under observation can be readily applied.

It should not be understood from the above, however, that the salt-bath
calibration cannot be made without plotting a curve; in actual
practice at least a hundred tests are made without plotting any curve
to one in which it is done. The observer, if awake, may reasonably
be expected to have sufficient appreciation of the lapse of time
definitely to observe the temperature at which the falling pointer
of the instrument halts. The gradual dropping of the pointer before
freezing, unless there is a large mass of salt, takes place rapidly
enough for one to be sure that the temperature is constantly falling,
and the long period of rest during freezing is quite definite.
The procedure of detecting the solidification point of the salt
by the hesitation of the pointer without plotting any curve is
suggested because of its simplicity.





Next: Complete Calibration Of Pyrometers

Previous: The Pyrometer And Its Use



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