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Steel MakingConclusionsMartien was probably never a serious contender for the honor ... The Electric Process The fourth method of manufacturing steel is by the electric f... Phosphorus PHOSPHORUS is an element (symbol P) which enters the metal fr... Annealing Alloy Steel The term alloy steel, from the steel maker's point of view, r... The Modern Hardening Room A hardening room of today means a very different place from ... The Packing Department In Fig. 56 is shown the packing pots where the work is packe... Tool Or Crucible Steel Crucible steel can be annealed either in muffled furnace or b... Steel Before The 1850's In spite of a rapid increase in the use of machines and the ... Alloying Elements Commercial steels of even the simplest types are therefore p... A Chromium-cobalt Steel The Latrobe Steel Company make a high-speed steel without tun... Blending The Compound Essentially, this consists of the sturdy, power-driven separa... Hardening Carbon Steel For Tools For years the toolmaker had full sway in regard to make of st... Silicon Silicon prevents, to a large extent, defects such as gas bubb... Highly Stressed Parts The highly stressed parts on the Liberty engine consisted of ... Optical System And Electrical Circuit Of The Leeds & Northrup Optical Pyrometer For extremely high temperature, the optical pyrometer is lar... Nickel-chromium A combination of the characteristics of nickel and the charac... Lathe And Planer Tools TO FORGE.--Gently warm the steel to remove any chill is parti... Preventing Decarbonization Of Tool Steel It is especially important to prevent decarbonization in such... Introduction Of Carbon The matter to which these notes are primarily directed is the... Piston Pin The piston pin on an aviation engine must possess maximum res... |
Correction For Cold-junction ErrorsCategory: PYROMETRY AND PYROMETERS The voltage generated by a thermo-couple of an electric pyrometer is dependent on the difference in temperature between its hot junction, inside the furnace, and the cold junction, or opposite end of the thermo-couple to which the copper wires are connected. If the temperature or this cold junction rises and falls, the indications of the instrument will vary, although the hot junction in the furnace may be at a constant temperature. A cold-junction temperature of 75 deg.F., or 25 deg.C., is usually adopted in commercial pyrometers, and the pointer on the pyrometer should stand at this point on the scale when the hot junction is not heated. If the cold-junction temperature rises about 75 deg.F., where base metal thermo-couples are used, the pyrometer will read approximately 1 deg. low for every 1 deg. rise in temperature above 75 deg.F. For example, if the instrument is adjusted for a cold-junction temperature of 75 deg., and the actual cold-junction temperature is 90 deg.F., the pyrometer will read 15 deg. low. If, however, the cold-junction temperature falls below 75 deg.F., the pyrometer will read high instead of low, approximately 1 deg. for every 1 deg. drop in temperature below 75 deg.F. With platinum thermo-couples, the error is approximately 1/2 deg. for 1 deg. change in temperature. Next: Correction By Zero Adjustment Previous: Optical System And Electrical Circuit Of The Leeds & Northrup Optical Pyrometer
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