VIEW THE MOBILE VERSION of www.steelmaking.ca Informational Site Network Informational
Privacy
   Home - Steel Making - Categories - Manufacturing and the Economy of Machinery

Steel Making

Hardness Testing
The word hardness is used to express various properties of me...

Making Steel Balls
Steel balls are made from rods or coils according to size, st...

Annealing
There is no mystery or secret about the proper annealing of d...

Sulphur
Sulphur is another impurity and high sulphur is even a greate...

Carbon-steel Forgings
Low-stressed, carbon-steel forgings include such parts as car...

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

Separating The Work From The Compound
During the pulling of the heat, the pots are dumped upon a ca...

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

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

Carbon In Tool Steel
Carbon tool steel, or tool steel as it is commonly called, us...

Pyrometers
Armor plate makers sometimes use the copper ball or Siemens' ...

Preparing Parts For Local Case-hardening
At the works of the Dayton Engineering Laboratories Company, ...

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

Annealing Method
Forgings which are too hard to machine are put in pots with ...

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

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

Machineability
Reheating for machine ability was done at 100 deg. less than ...

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

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

Tool Or Crucible Steel
Crucible steel can be annealed either in muffled furnace or b...



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



Add to del.icio.us Add to Reddit Add to Digg Add to Del.icio.us Add to Google Add to Twitter Add to Stumble Upon
Add to Informational Site Network
Report
Privacy
SHAREADD TO EBOOK


Viewed 2974