Nichrome heating wire

The unpacked column should be wrapped with a heating tape, or Nichrome heating wire, and kept at ca. 110° throughout the decomposition. 

Silicone oil bath with nichrome heating wire... 

Electric tube furnaces of appropriate dimensions are available from various manufacturers. A model RO 4/25 by Heraeus GmbH, Hanau, FRG is suitable. However, a very satisfactory furnace can be built by any well equipped laboratory workshop at little cost and effort. The material required consists of thin walled ceramic tubing, 3.5 cm i.d., nichrome resistance wire, heat resistant insulation, and ordinary hardware material. A technical drawing will be provided by the submitters upon request. The temperature of the furnace can be adjusted by an electronic temperature controller using a thermocouple sensor. A 1.5 kW-Variac transformer and any high temperature thermometer would do as well for the budget-minded chemist. 

The checkers used a Hoskins tube furnace, type FD303A (Central Scientific Co.), 17 in. long. The heater for the sublimation vessel was wound in two sections with heating wire in such a way that a decreasing temperature gradient in the direction of the pyrolysis oven was maintained. The open end of the heater was closed by an asbestos end plate which could be heated independently by a small nichrome coil. 

A ring of nichrome wire heated to 1000 °C by an electric current is used to ignite the sample. The heated wire is brought into contact with the base of the pile. The maximum contact time is 10 sec. 

Furnaces. Electric furnaces are used for higher temperatures. These are obtainable commercially, but satisfactory ones can be made in the laboratory (see Fig. 24-1). A pregrooved Alundum core is wound with suitable heating wire (nichrome, Chromel A, Kanthal) of 12 to 20 gauge, and covered with a thick coating of Alundum cement. This is surrounded by several inches of powdered magnesia, for thermal insulation, in a large... 

Gas chromatography coupled with AAS has been the most popular hyphenated technique for the speciation of metals and organometals. Among different atomizer designs employed in coupling GC with AAS, electrothermal atomization, especially the electrother-mally heated quartz tube, is preferred because of its high sensitivity, simple operation, and low cost [6]. The quartz tube (—100 X 10 mm inner diameter) is usually constructed in house and wrapped with Nichrome resistance wire and ceramic isolation material. A thermocouple is attached to the surface of the quartz burner for temperature control (Fig. 1). If necessary, hydrogen and air can be supplied from side arms of the burner. The furnace can be heated to more than 1000°C by means of a variable transformer. 

In the case of the sulfur-rich mixtures of sulfur and phosphorus, approximately 120 grams of the mixture was placed in a borosilicate glass beaker, which was covered with a niobium plate at the higher temperatures (>350°C) to decrease sulfur losses by vaporization. The cell was placed in a 500 ml alumina secondary container, and this assembly was located inside a sealed stainless steel vessel which was heated by Nichrome resistance wire. The cover of the vessel had access ports for a stirring... 

Electrically heated oil baths, which typically contain either mineral oil or silicone oil, are commonly employed in the laboratory. These baths are heated either by placing the bath container on a hot plate or by inserting a coil of Nichrome resistance wire in the bath. In the latter case, the resistance wire serves as the heating element and is attached to a transformer with an electrical cord and plug (Fig. 2.24). Thermal equilibration within the bath is maintained by placing a paper clip or stirbar in the bath and using a magnetic stirrer (Sec. 2.11). 

Figure 4.3 Suggested methods to shrink heat shrink tubing (A) heat gun with concentrator adapter (B) nichrome resistance wire (powered with a variac).

Whiskers and filaments of graphite have also been observed to form during pyrolytic deposition of various hydrocarbon materials. Hillert and Lange " studied the thermal decomposition of n-hep-tane and reported the formation of filamentous graphite on iron surfaces at elevated temperatures. Pyrolysis of methane" and carbon monoxide" on iron surfaces or heated carbon filaments also resulted in the formation of similar structures as well as the thermal decomposition of acetylene on Nichrome alloy wires below 700°C."... 

Heating equipment. Flexible Nichrome heater wire consisting of a Nichrome inner wire, asbestos and glass insulation, and a flexible stainless steel protective braid, is extremely useful for maintaining systems at temperatures up to 1100°F for periods of time in excess of 10,000 hr [22]. Figure 23-6 shows the application of this type of heater in loop work. Strip and tubular heaters have been in in-pile service for over 8000 hr [34]. A resistance heater has also been used as an internal heater submerged in a lead-bismuth eutectic system [29]. 

Nichrome (material) The trade name for an alloy (Ni, Fe, Cr) that is often used for metallization and for resistively heated wires. 

The furnace and thermostatic mortar. For heating the tube packing, a small electric furnace N has been found to be more satisfactory than a row of gas burners. The type used consists of a silica tube (I s cm. in diameter and 25 cm. long) wound with nichrome wire and contained in an asbestos cylinder, the annular space being lagged the ends of the asbestos cylinder being closed by asbestos semi-circles built round the porcelain furnace tube. The furnace is controlled by a Simmerstat that has been calibrated at 680 against a bimetal pyrometer, and the furnace temperature is checked by this method from time to time. The furnace is equipped with a small steel bar attached to the asbestos and is thus mounted on an ordinary laboratory stand the Simmerstat may then be placed immediately underneath it on the baseplate of this stand, or alternatively the furnace may be built on to the top of the Simmerstat box. 

Excellent results are obtained by passing acetone vapour over an electrically heated nichrome wire spiral an apparatus, incorporating the latter, is described in the experimental section. 

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