Working ambient

The working (ambient) temperature must be kept below 14°F, or... 

This first thermal event identified in the hard tissues with the temperature increase is ascertained to the evaporation of the water absorbed in the tissue volume. Within the bone tissue the water can be found adsorbed or in the hydroxyapatite crystalline structure. The evaporation of adsorbed water does not influence the hydroxyapatite lattice parameters [39], and occurs in the 25-250 °C range regardless the analyzed bone type (cortical or cancellous), with slight temperature variations due to the analyzed specimens, working ambient, sample preparation method [6,7, 12,19, 29,30,32,42] or tissue health status [31,43]. Important variations of the temperature, where the evaporation of the adsorbed water occurs, were recorded in the case of samples derived from dental tissues [43]. 

Condensable hydrocarbon components are usually removed from gas to avoid liquid drop out in pipelines, or to recover valuable natural gas liquids where there is no facility for gas export. Cooling to ambient conditions can be achieved by air or water heat exchange, or to sub zero temperatures by gas expansion or refrigeration. Many other processes such as compression and absorption also work more efficiently at low temperatures. 

To examine a sample by inductively coupled plasma mass spectrometry (ICP/MS) or inductively coupled plasma atomic-emission spectroscopy (ICP/AES) the sample must be transported into the flame of a plasma torch. Once in the flame, sample molecules are literally ripped apart to form ions of their constituent elements. These fragmentation and ionization processes are described in Chapters 6 and 14. To introduce samples into the center of the (plasma) flame, they must be transported there as gases, as finely dispersed droplets of a solution, or as fine particulate matter. The various methods of sample introduction are described here in three parts — A, B, and C Chapters 15, 16, and 17 — to cover gases, solutions (liquids), and solids. Some types of sample inlets are multipurpose and can be used with gases and liquids or with liquids and solids, but others have been designed specifically for only one kind of analysis. However, the principles governing the operation of inlet systems fall into a small number of categories. This chapter discusses specifically substances that are normally liquids at ambient temperatures. This sort of inlet is the commonest in analytical work. 

Spiral-wound modules are much more commonly used in low pressure or vacuum gas separation appHcations, such as the production of oxygen-enriched air, or the separation of organic vapors from air. In these appHcations, the feed gas is at close to ambient pressure, and a vacuum is drawn on the permeate side of the membrane. Parasitic pressure drops on the permeate side of the membrane and the difficulty in making high performance hollow-fine fiber membranes from the mbbery polymers used to make these membranes both work against hollow-fine fiber modules for this appHcation. 

Peroxohydrates are usually made by simple crystallization from solutions of salts or other compounds in aqueous hydrogen peroxide. They are fairly stable under ambient conditions, but traces of transition metals catalyze the Hberation of oxygen from the hydrogen peroxide. Early work on peroxohydrates has been reviewed (92). 

Fractional crystallisation is based on favorable solubiUty relationships. Potassium chloride is much more soluble at elevated temperatures than at ambient temperatures in solutions that are saturated with sodium and potassium chlorides. Sodium chloride is slightly less soluble at elevated temperatures than at ambient temperatures in solutions that are saturated with KCl and NaCl. Working process temperatures are usually 30—110°C. The system,... 

Because of the complexity of designs and performance characteristics, it is difficult to select the optimum atomizer for a given appHcation. The best approach is to consult and work with atomizer manufacturers. Their technical staffs are familiar with diverse appHcations and can provide valuable assistance. However, they will usually require the foUowing information properties of the Hquid to be atomized, eg, density, viscosity, and surface tension operating conditions, such as flow rate, pressure, and temperature range required mean droplet size and size distribution desired spray pattern spray angle requirement ambient environment flow field velocity requirements dimensional restrictions flow rate tolerance material to be used for atomizer constmction cost and safety considerations. 

At ambient temperatures beryUium is quite resistant to oxidation highly poHshed surfaces retain the brilliance for years. At 700°C oxidation becomes noticeable in the form of interference films, but is slow enough to permit the working of bare beryUium in air at 780°C. Above 850°C oxidation is rapid to a loosely adherent white oxide. The oxidation rate at 700°C is paraboHc but may become linear at this temperature after 24—48 hours of exposure. In the presence of moisture this breakaway oxidation occurs more rapidly and more extensively. BeryUium oxide [1304-56-9] BeO, forms rather than beryUium nitride [1304-54-7] Be2N2, but in the absence of oxygen, nitrogen attacks beryUium above 900°C. 

The most commercially important application that takes advantage of the pyroelectric effect ia polycrystalline ceramics is iafrared detection, especially for wavelengths ia excess of 2.5 p.m. AppHcations range from radiometry and surveillance to thermal imaging, and pyroelectric materials work under ambient conditions, unlike photon detectors, which require cooling. 

Refrigeration is an extremely valuable utiUty because of the work required to raise the energy to ambient temperature. Its value goes up direcdy as the temperature gap between ambient and use level goes up. For example, whereas refrigeration at —25° C is worth approximately as much as heat at 250°C, refrigeration at —75°C is worth twice as much. 

Ambient-cure systems are often based on lower molecular-weight soHd epoxy resins cured with aUphatic polyamines or polyamides. Curing normally occurs at ambient temperatures with a working life (pot life) of 8—24 h, depending on the formulation. Epoxy—poly amine systems are typically used for maintenance coatings in oil refineries, petrochemical plants, and in many marine appHcations. Such coverings are appHed by spray or bmsh. These are used widely where water immersion is encountered, particularly in marine appHcations (see COATINGS, MARINE). 

Bimetallie elements are widely used in instruments sueh as thermostats to sense or eon-trol temperatures. There are several bimetallie element types available, sueh as straight strips, eoils and dises, but all rely on the same working prineiple. In its most basie form, the bimetallie strip eomprises of two dissimilar metal strips bonded together, usually of the same surfaee area, but not neeessarily of the same thiekness thermostat. The eom-posite metal strip is elamped at one end to aet as a eantilever beam, and is horizontal at a partieular temperature. When the temperature is inereased, the strip defleets in the direetion of the metal with the least eoeffieient of linear expansion. Its working prineiple relies on the faet that the metals will expand at different rates as the strip is heated. The purpose of this defleetion is to typieally eause the strip to make eontaet with a switeh or eomplete an eleetrie eireuit at a partieular setpoint temperature above the ambient. 

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