Refrigerator Laboratory

Formaldehyde is one of the most recommended disinfectants for space decontamination. It is widely used to disinfect safety cabinets, incubators, refrigerators, laboratory rooms, buildings, and other enclosed spaces (427). Formaldehyde vapors can be generated fi om aqueous solutions (formalin) containing 37 to 40 percent formaldehyde by heating or by vaporizing the solution. Formaldehyde gas... 

Carbon dioxide is used in the manufacture of sodium carbonate by the ammonia-soda process, urea, salicyclic acid (for aspirin), fire extinguishers and aerated water. Lesser amounts are used to transfer heat generated by an atomic reactor to water and so produce steam and electric power, whilst solid carbon dioxide is used as a refrigerant, a mixture of solid carbon dioxide and alcohol providing a good low-temperature bath (195 K) in which reactions can be carried out in the laboratory. 

Batch vs Continuous Reactors. Usually, continuous reactors yield much lower energy use because of increased opportunities for heat interchange. Sometimes the savings are even greater in downstream separation units than in the reaction step itself Especially for batch reactors, any use of refrigeration to remove heat should be critically reviewed. Batch processes often evolve Httle from the laboratory-scale glassware setups where refrigeration is a convenience. 

Small refrigerators were developed by several companies and some were even installed in hotel rooms in Chicago. Borg-Wamer and other companies produced many compact systems for laboratory uses (23). Air-Industry in Erance built an air conditioning system for a passenger railway coach that was stiH in daily use after 10 years of operations without a single thermoelectric failure (24). 

The best sub-atmospheric refrigerant is water. Unfortunately it is not strongly adsorbed by carbons, but refrigerators and heat pumps based on water - zeolite pairs have been built and tested in research laboratories. Methanol is adsorbed well by carbons and a solar refrigerator based on a carbon - methanol pair was marketed by Brissoneau et Lotz Marine in France. Methanol is environmentally friendly, but deeomposes at temperatures around 150°C and so camiot be used for very high temperature cycles. 

Other refrigerants, including CFCs Rll and R12, HCFC R22, HFC R32 and hydrocarbons such as butane have been evaluated in detail by Critoph [3,4] but are significantly worse in performance than methanol or ammonia. In 1996, these two refrigerants are the only ones used in the major laboratories working on carbon adsorption cycles. 

Ammonia is shipped as a liquefied gas under its own vapour pressure of 114 psig (7.9 bar) at 21°C. Uses are to be found in refrigeration, fertilizer production, metal industries, the petroleum, chemical and rubber industries, domestic cleaning agents and water purification. Aqueous solutions of ammonia are common alkaline laboratory reagents ca 0.88 solution is the strongest available. Ammonia gas is expelled on warming. 

ASHRAE 110-1995. Method of Testing Laboratory Fume Hoods. Atlanta.. American Society of Heating, Refrigeration, and Air-conditioning Engineers, 1995. 

ASHRAE 41.2-1987. Methods for Laboratory Air Flow Measurement. American Societv of Heating, Refrigerating, and Air-conditioning Engineers, Atlanta, 1987. 

It is not miusual to find reaction flasks containing volatile solvents stored in research laboratory refrigerators. Consider tlie following a 500 iiiL flask of dietliyl ether (MW=74.14 g/gniol, specific gravity=0.713) is stored in a 15 ft, unventilated refrigerator at 41°F and 1 atm. (Note the vapor pressure of dietliyl ether at 41°F is 200 imii Hg). 

International Institute of Refrigeration, Recent Advances and Developments in the refrigeration of Meat, Symposium at Bristol Laboratory, HR, 1986 BAILEY, c. and cox R. p.. The chilling of beef carcases. Proceedings of the Institute of Refrigeration, May, 1976... 

There is more to a laboratory than work benches and the instruments mounted on them. Free-standing equipment must also be considered. This includes refrigerators, safety storage cabinets for chemicals, safety shower, desk space, typewriter stand or computer terminal, or any other equipment that is not bench-mounted. File cabinets, which are real space-robbers, must not be forgotten. In one laboratory, much space was saved by placing two-drawer file cabinets beneath the large table used for sorting samples. 

Gradually all things that are to go into the laboratory, such as work benches, refrigerators, safety storage cabinets, floor-mounted equipment, desks, file cabinets, balance tables, and a myriad of other items, are in place. Now is another good time to check on traffic patterns. Will a piece of equipment stick out too far Will a desk chair cause obstruction Will the refrigerator door cause problems when open These are just a few of the questions that should be asked again. 

In another laboratory, the chemist was annoyed by the fact that so much ether evaporated from containers in hot weather. He decided to store the ether in a regular household refrigerator... 

Urine may be collected for assays of enzyme activities following cleansing of the genitalia with mild antiseptic soap followed by rinsing with water. The urine is collected in a chemically clean container with no preservative. As the activity of urinary enzymes is a function of the volume of the specimen it is important to time the collection accurately. A collection period of 8 hours is quite adequate, and the use of longer periods is not desirable because enzyme activities can rapidly decrease in the relatively hostile medium of the urine. The urine should be refrigerated and transferred promptly to the laboratory, where it should also be processed promptly. 

Trichloroethylene has also been detected in ground water at the U.S. Army Cold Regions Research and Engineering Laboratory in Hanover, NH, where it was used as a refrigerant between 1960 and 1987 (Hewitt and Shoop 1994). In water collected directly after well instillation, the trichloroethylene concentrations were 0.044-180 ppm. 

Maceration of crnshed or gronnd material in methanol containing small amounts of HCl (<1%) is commonly used at refrigerated temperatures for times ranging from a few hours to overnight. The extracted material is usually too dilute for further analyses and the extraction procednre is usually followed by evaporation of the methanol using vacnnm and mild temperatures (30 to 40°C). Alternatively, the plant materials and solvents can be mixed well with a laboratory blender for a few minutes or a chemical-resistant stir bar for a longer time. Concentration of anthocyanin extracts can be done by rotary evaporation under vacuum conditions for volatile solvents or lyophilization for water. 

Pyruvic acid is not stable at ambient temperature when it is stored for a long period of time. It can only be stored in a refrigerated room. A bottle of this acid was stored in a laboratory at 25°C and detonated, probably because of the overpressure created by the formation of carbon dioxide. Indeed, with diacids and complex acids the decomposition is made by decarboxylation. In this particular case, this decomposition should give rise to acetaldehyde. It could be asked whether, in the exothermic conditions of this decomposition, a polymerisation of this aldehyde (see Aldehydes-ketones on p.310) did not make the situation worse. 

To investigate a vertical distribution of a chemical, a sediment column is divided into sections with appropriate thickness. The sediment column taken in a pipe should be refrigerated in an ice-cooled container, transported to the laboratory, and removed carefully on to a clean tray so that there is as little disturbance as possible to the soil core structure. In the case of a column in which there is little soil moisture and it tends to collapse, the soil should be pushed out to each required thickness and carved off. It is also possible to take a sediment column up to a 30-cm depth using a pipe that is connected to cylinders (5-cm height) with sealing tape. In this case, the sample in each 5-cm fraction can be obtained as it is, after removing the tape. 

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