Temperature control liquid baths

The preferential oxidation process consists of adding sufficient air to the mixed gas to give a slight excess over that required for the oxidation of the monoxide, saturating the mixture with water vapor at a temperature somewhat above room (about 40° C.) and passing it over the catalyst contained in narrow bore copper tubes immersed in a temperature controlled liquid bath. The water vapor exhibits a selective poisoning action toward hydrogen oxidation, 5 apparently independent of concentration and of catalyst temperature. 

GLC can also be used to determine the partial pressure of a solute in a polymer solution at concentrations as great as 50 wt% solute. In this case of finite concentration IGC, a uniform background concentration of the solute is established in the carrier gas. The carrier gas is diverted to a saturator through a metering valve. In the saturator it passes through a diffuser in a well-stirred, temperature-controlled liquid bath. 

The hot liquid agar medium was mixed by magnetic stirring and cooled to 45 °C in a temperature-controlled water bath. Then the agar was poured into three Petri dishes and solidified by cooling to room temperature. 

The combined filtrates containing benzonitrile oxide are transferred to a 1-1. round-bottomed flask, treated immediately with 13.9 g. (0.1 mole) of N-sulfinylaniline added in one portion, with swirling, and set aside protected from moisture, while the temperature reaches a maximum of 33-34° (usually IS minutes). The mixture is then heated to reflux, protected from moisture, in a temperature-controlled oil bath for 3-5 hours. Continuous evolution of sulfur dioxide takes place during this period at the end of which the mixture is cooled and evaporated under reduced pressure (Note 3) at 70-80° to remove the solvent. The residual dark brown liquid is transferred to a 50-ml., pear-shaped distilling flask (Note 13) and heated, protected from moisture, at 110° for 30 minutes to complete the decomposition. It is then cooled and distilled under high vacuum (Note 14). Unchanged N-sulfinylaniline (2.0-2.5 g.) distills over at 45-50° (0.1-0.2 mm.). A second fraction (1.2-1.5 g.) is collected until the temperature reaches 112° (Note 15) then diphenyl carbodiimide is collected at 114-117° (0.1-0.2 mm.) as a clear yellow liquid yield 10.5-10.8 g. (54-56%) (Note 16) 1.6355 ... 

Water Bath, a thermostatically controlled liquid bath capable of maintaining a water temperature of 60 1 C (140 2 F). 

A liquid flow microcalorimeter, the thermal activity monitor (TAM), is commercially available from ThermoMetric (formerly LKB/Bofors). This instrument consists of two glass or steel ampules with a volume of 3 to 4 cm3 (25 cm3 ampule available with a single detector), placed in a heat sink block. Recently, an injection-titration sample vessel was developed which acts as a microreactor. This vessel is provided with flow-in, flow-out, and titration lines, with a stirring device. The isothermal temperature around the heat sink is maintained by a controlled water bath. Each vessel holder, containing an ampoule, is in direct contact with a thermopile array, and the two arrays are joined in series so that their output voltages subtract. The two pairs of thermopile arrays are oppositely connected to obtain a differential output,... 

A method for measuring the uniaxial extensional viscosity of polymer solids and melts uses a tensile tester in a liquid oil bath to remove effects of gravity and provide temperature control cylindrical rods are used as specimens (218,219). The rod extruder may be part of the apparatus and may be combined with a device for clamping the extruded material (220). However, most of the more recent versions use prepared rods, which are placed in the apparatus and heated to soften or melt the polymer (103,111,221—223). A constant stress or a constant strain rate is applied, and the resultant extensional strain rate or stress, respectively, is measured. Similar techniques are used to study biaxial extension (101). 

An intimate mixture of 600 g. of finely powdered freshly fused potassium acid sulfate and 400 g. of powdered tartaric acid, prepared by grinding them together in a mortar, is placed in a 3-I. round-bottom Pyrex flask connected with a condenser which is filled with water but does not have any water flowing through it. The mixture is heated by means of an oil bath maintained at a temperature between 210 and 220° until liquid no longer distils over. Some foaming takes place (Note 1), but if fused potassium acid sulfate is used and the temperature of the bath does not rise above 220°, it is not difficult to control. The distillate is then fractionated under reduced pressure. Pyruvic acid passes over at 75-80 725 mm. and the yield is 117-128 g. (50-55 per cent of the theoretical amount). 

Fig. 12.2 Time dependencies of sonophotocatalytic reaction products from pure water. As powdered photocatalyst, Ti02-A (200mg, Soekawa, Commercial Reagent, rutile-rich type and specific surface area 1.9 m2/g) was used without further treatment. Liquid water (150 cm3, Wake, Distilled water for HPLC was used as reactant and was purged with argon, a Pyrex glass bulb (250-300 cm3) was used as a reactor and was placed m a temperature-controlled bath (EYELA NTT-1200 and ECS-0) all time. After the glass bulb was sealed, the irradiation was carried out under argon atmosphere at 35°C. Photo and ultrasonic irradiations were performed from one side with a 500 W xenon lamp (Ushio, UXL500D-O) and from the bottom with an ultrasonic generator (Kaijo. TA-4021-4611, 20C kHz 200 W), respectively.

Dissolve 46.5 g (45.5 ml, 0.5 ml) of aniline in a mixture of 126 ml of concentrated hydrochloric acid and 126 ml of water contained in a 1-litre beaker. Cool to 0-5 °C in a bath of ice and salt, and add a solution of 36.5 g (0.53 mol) of sodium nitrite in 75 ml of water in small portions stir vigorously with a thermometer and maintain the temperature below 10 °C, but preferably at about 5 °C by the addition of a little crushed ice if necessary. The diazotisation is complete when a drop of the solution diluted with 3-4 drops of water gives an immediate blue coloration with potassium iodide-starch paper the test should be performed 3-4 minutes after the last addition of the nitrite solution. Prepare a solution of 76 g (0.69 mol) of sodium fluoroborate (1) in 150 ml of water, cool and add the chilled solution slowly to the diazonium salt solution the latter must be kept well stirred and the temperature controlled so that it is below 10 °C. Allow to stand for 10 minutes with frequent stirring. Filter the precipitated benzenediazonium fluoroborate with suction on a Buchner funnel, drain well and wash the yellow solid with about 30 ml of ice-water, 15 ml of methanol and 30-40 ml of ether suck the solid as free as possible from liquid after each washing (2). Spread the salt upon absorbent filter paper and allow to dry overnight, if possible in a current of air. The yield of benzenediazonium fluoroborate is 60—65 g the pure salt melts with decomposition at 119-120 °C. 

The reaction is initiated by the addition of a reactant, which must be exactly at the same temperature as the Dewar contents, in order to avoid the sensitive heat effects. Then the temperature is recorded as a function of time. The obtained curve must be corrected for the heat capacity of the Dewar flask and its inserts, respective of their wetted parts, which are also heated by the heat of reaction to be measured. The temperature increase results from the heat of reaction (to be measured), the heat input by the stirrer and the heat losses. These terms are determined by calibration, which may be a chemical calibration using a known reaction or an electrical calibration using a resistor heated by a known current under a known voltage (Figure 4.2). The Dewar flask is often placed into thermostated surroundings as a liquid bath or an oven. In certain laboratories, the temperature of the surroundings is varied in order to track the contents temperature and to avoid heat loss. This requires an effective temperature control system. 

To experimentally validate the Gitterman model, we prepared an artificial seawater sample that had the composition of seawater s liquid partially frozen down to — 23 °C (Marion et al. 1999). To this sample we added an excess of mirabilite crystals to ensure an adequate sulfate source. The sample was then placed in a — 26 °C temperature-controlled bath and allowed to equilibrate with periodic sampling and analyses over a 12-week period. The precipitation of hydrohalite between — 23 °C and — 26 °C (Fig. 3.16) led to an initial decrease in the sodium molality. Magnesium, on the other hand, was conserved in the solution phase, as ice formed and hydrohalite precipi-... 

Let us first restrict to the simpler and more frequently encountered case that the feed mixture consists of vapors of a single component B in the carrier gas A. The optimum device, both at ambient and elevated pressure, will then be a saturator which contains component B in the solid or liquid state (Fig. 2). On its way through the saturator, the carrier gas A is loaded with vapors of B. Since its vapor pressure depends exponentially on the temperature, the saturator must be thoroughly thermostated. An externally thermostated water or oil bath circulating through a jacket around the saturator is often the best solution. If temperatures above ca. 200 °C are required, a saturator surrounded by a stirred bath of molten salt with an efficient temperature control can be used alternatively. 

The mixture was used as purchased from Fluka AG. The submitters have occasionally used, as a bath liquid, petroleum ether (bp 40-60°C) of unknown composition or pure isopentane (mp — 160°C). In such cases, temperature control is necessary it was achieved with a platinum temperature sensor inside the reaction mixture. 

Circulating Liquid Baths. These devices consist of a fluid reservoir, a heater, a temperature sensor, a controller, and a circulating pump. Commoidy used general-purpose baths are made by Haake, Lauda, and Omega Engineering. Some of these have refrigeration units and are designed for operation at low temperatures (typically down to 20°C but sometimes to 35°C or even -70°C), as well as above room temperature. 

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