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Steel MakingBlending The CompoundEssentially, this consists of the sturdy, power-driven separa... Testing And Inspection Of Heat Treatment The hard parts of the gear must be so hard that a new mill f... Hardness Testing The word hardness is used to express various properties of me... Tempering Colors On Carbon Steels Opinions differ as to the temperature which is indicated by t... The Quenching Tank The quenching tank is an important feature of apparatus in c... The Effect Of Tempering On Water-quenched Gages The following information has been supplied by Automatic and ... Steel Before The 1850's In spite of a rapid increase in the use of machines and the ... Annealing ANNEALING can be done by heating to temperatures ranging from... Pickling The Forgings The forgings were then pickled in a hot solution of either ni... Heat Treatment Of Milling Cutters Drills Reamers Etc THE FIRE.--Gas and electric furnaces designed for high heats ... Correction By Zero Adjustment Many pyrometers are supplied with a zero adjuster, by means ... Critical Points One of the most important means of investigating the properti... Complete Calibration Of Pyrometers For the complete calibration of a thermo-couple of unknown e... High Speed Steel For centuries the secret art of making tool steel was handed ... Brown Automatic Signaling Pyrometer In large heat-treating plants it has been customary to mainta... Cutting-off Steel From Bar To cut a piece from an annealed bar, cut off with a hack saw,... Carbon Tool Steel Heat to a bright red, about 1,500 to 1,550 deg.F. Do not ham... Hardening Operation Hardening a gear is accomplished as follows: The gear is tak... Lathe And Planer Tools TO FORGE.--Gently warm the steel to remove any chill is parti... Chromium Chromium when alloyed with steel, has the characteristic func... |
Complete Calibration Of PyrometersCategory: PYROMETRY AND PYROMETERS For the complete calibration of a thermo-couple of unknown electromotive force, the new couple may be checked against a standard instrument, placing the two bare couples side by side in a suitable tube and taking frequent readings over the range of temperatures desired. If only one instrument, such as a millivoltmeter, is available, and there is no standard couple at hand, the new couple may be calibrated over a wide range of temperatures by the use of the following standards: Water, boiling point 212 deg.F. Tin, under charcoal, freezing point 450 deg.F. Lead, under charcoal, freezing point 621 deg.F. Zinc, under charcoal, freezing point 786 deg.F. Sulphur, boiling point 832 deg.F. Aluminum, under charcoal, freezing point 1,216 deg.F. Sodium chloride (salt), freezing point 1,474 deg.F. Potassium sulphate, freezing point 1,958 deg.F. A good practice is to make one pyrometer a standard; calibrate it frequently by the melting-point-of-salt method, and each morning check up every pyrometer in the works with the standard, making the necessary corrections to be used for the day's work. By pursuing this course systematically, the improved quality of the product will much more than compensate for the extra work. The purity of the substance affects its freezing or melting point. The melting point of common salt is given in one widely used handbook at 1,421 deg.F., although chemically pure sodium chloride melts at 1,474 deg.F. as shown above. A sufficient quantity for an extended period should be secured. Test the melting point with a pyrometer of known accuracy. Knowing this temperature it will be easy to calibrate other pyrometers. Next: Placing Of Pyrometers Previous: Calibration Of Pyrometer With Common Salt
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