Refrigerant baths

The bath temperature can also be controlled with an immersion cooler that has been found to be practical for temperatures down to about -80°C [23]. Suggested coolant fluids are methanol [5,23] and 2-propanol [11]. High-power coolers for temperatures as low as -100°C are manufactured by FTS Systems, Inc., Stone Ridge, NY. There are many manufacturers of refrigerated baths for less demanding temperatures. 

The aforementioned refrigerated baths are often equipped with circulation pumps so that the chilled fluid can be passed through the jacket of a nearby electrochemical cell. The tubing connecting the circulator to the cell should be insulated to minimize heat loss. With such a circulator, experiments have been conducted at temperatures as low as -20°C [29,30], and there appears to be no reason that lower temperatures can not be achieved. 

The actual temperature of the solution in the vicinity of the working electrode should be measured. It is not wise to assume that the solution temperature equals that of the bath, particularly when using a circulating refrigerated bath, because the temperature of the coolant will rise on passage from the bath to the cell. Low-temperature thermometers can be used in principle, but the almost universal choice is a thermocouple. Many commercial units are available with digital output and control features. The thermocouple junction can be coated with Teflon and inserted directly into the cell. 

Cryostat. This is a refrigerated bath held at a constant low temp. Its construction operation vary widely depending on temp, reqd accuracy of temp regulation, and refrigerant. 

The checkers used a constant temperature refrigerated bath (Cryocool). 

The principal types of vacuum pumps will be discussed in this section. The water aspirator is a crude but useful pump for many routine operations. Rotary oil pumps are used for pumping on refrigerant baths and as the forepump for backing low-pressure pumps. For most high-vacuum work, diffusion pumps are utilized to achieve pressures... 

The checkers used an electrical refrigeration bath to maintain this reaction temperature. 

A.B SOLVENT PUMPS C EXTRACTION COLUMN 0 CONSTANT TEMPERATURE BATH E PREHEATER P HEATER-CIRCULATOR G THROUGH - WINDOW RUSK A CELL H REFRIGERATED BATH COOLER t MICROMETERING VALVE... 

For short-time storage, the sulfur(VI) fluoride is conveniently condensed in roomy pyrex traps that are cooled by an alcohol-solid carbon dioxide refrigerating bath J (or a similar combination). These traps may be, for example, about 20 to 25 cm. tall and 40 to 45 mm. wide with an inner (outlet) tube not less than 10 mm. wide leading down to within about 10 cm. from the bottom of the trap. Stopcocks are provided on inlet and outlet tubes. 

Tiselius (1938a) also constructed a special preparative apparatus for large-scale preparations. It was built after the same principles as the analytical model, but with ten times greater dimenaons. This apparatus is shown in Fig. 25. The U-tube consisted of a bottom cell, four intermediate sections, and a top cell. The cross-section area of the TJ-tube was 7.5 cm. The electrode tubes were of 5-1. capacity each due to thdr large dimendons, they were kept outside the refrigerating bath. The coimection tubes between U-tube and electrode tubes were bent as shown in the figure in order to prevent the colder and heavier solution in the U-tube from falling down into the electrode tubes if it did, it would stir up the chloride solution around the electrodes. 

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