Laboratory heating methods

A similar unit, modified in details such as location of condenser, use of an agitator and shape of the vessel, was used by Fisher and Whitney . Further substantial modifications to permit interface location of specimens, cooling of specimens and operation under applied pressure, have been described by Fisher . Earlier laboratory test methods tried by Fisher and Whitney included exposure of specimens heated by their own electrical resistance and of tubular specimens containing a pencil-type resistance-wire heater in a quartz tube. 

Hagglund and Enkvist (6) developed a laboratory scale method for manufacturing methyl sulfide from kraft black liquor by pressure heating after addition of sodium sulfide. This process was later taken over by Crown-Zellerbach in the United States and developed in pilot plant and full scale. However, the yield is only about 7% of the initial lignin utilized in the process. 

Sheets of thermoplastic material may be hot-formed into a variety of smooth shapes by heating the sheet in an oven to a temperature at which it becomes pliable. The sheet is then bent over a form. In the laboratory this method is... 

Applying a correction to the temperature rise observed makes an allowance for losses of heat by radiation from the calorimeter. This correction is expressed by a formula that appears to be complicated, but if the various temperature figures are set out on the laboratory sheet methodically, it is not only easy to apply, but the liability of introducing arithmetic errors is reduced. 

One of several advantages of the water bath heating method is the ready availablility of water baths in most clinical laboratories. Temperature settings just below the boiling point of water (95-99 °C) are most commonly used. 

All evidence indicated that the cylinder ruptured due to the hydrostatic pressure of expanding liquid ammonia due to excessive heat on the cylinder. Fragments of the cylinder were sent to a testing laboratory for failure analysis. The ruptured cylinder was a full cylinder just put in service. According to the company s literature search, a full cylinder would become hydrostatically full of liquid ammonia at about 130° F (54.4° C). If the liquid was further heated, tremendous pressures would be developed. An alternate possibility was that the cylinder was heated to 250° F (121° C) (the steam supply temperature). Raising the temperature that high is unlikely with the crude heating methods and the expected heat losses, but if they were, the internal cylinder pressure could reach... 

While all vapor techniques depend on a condensation step, the direct vaporization techniques begin with the desired composition and evaporate or sublimate the material. This is straightforward and allows a diversity of compositions to be used, but excessively high temperatures are demanded to vaporize refractory ceramics. Various heating methods used, including dc arcs, dc plasmas, rf plasmas, and electron beam heating. These techniques are not popular for large-scale production or routine laboratory powder preparation. 

Mor and Perez (1994) presented a critical evaluation of Ono s method (powder mount only) using laboratory heating stages, concluding that the alite size and alite birefringence did not correlate. Correlation was said to be much better with regard to belite size and color. The correspondence between laboratory and industrial kiln microscopy was seriously questioned and differences in environmental conditions, mainly atmospheric composition, were alleged to be responsible. 

Heating liquids on an open plate or water bath is very inconvenient in a ship s laboratory. Several methods in Part IV call for prolonged heating at 100 C. An electrically heated sand bath can be used but we recommend an electrically heated metal block with holes drilled for the various containers. Such blocks are easily constructed, or a suitable piece of equipment (with some modification) can be purchased directly from Hallikainen Instruments, Berkeley, California, USA. 

Two production heats of INOR-8 of 10,000 lb each and numerous smaller heats of up to 5000 lb have been melted and fabricated into various shapes by normal production methods. Evaluation of these commercial products has shown them to have properties similar to those of the laboratory heats prepared for material selection. Purchase orders are filled by the vendors in one to six months, and the costs range from 2.00 per pound in ingot form to 10.00 per pound for cold-drawn welding wire. The costs of tubing, plate, and liar products depend to a large extent on the specifications of the finished products. 

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