Equipment heating

A variety of heating equipment is used in a laboratory, namely, gas burners, plates, baths, furnaces, drying cabinets, etc. 

Burners. The most convenient one is the Teklu burner (Fig. la) because its design enables one to regulate not only the inflow of air, but also that of gas. The latter enters the base of a Teklu burner via side connection 1, whence it passes along narrow tube 2 into tapered tube 3, where it mixes with air. In addition to a gas cock, the supply of gas can also be regulated by screw 4. Air enters the 

Air enters a Bunsen burner (Fig. lb) through orifice 1 in the lower part of the upper tube. The opening of this orifice can be controlled by rotating sleeve 2 provided with a mating orifice. 

The greatest amount of heat is obtained in complete combustion of the gas, when the flame is non-lu-minous. When the supply of air is reduced, the flame becomes luminous and smoky. To ignite a burner, shut off the access of air to it, light a match, open the gas cock, and after one or two seconds apply the lighted match to the edge of the burner opening. Make the flame non-luminous by increasing the inflow of air. 

How can the luminosity of a flame be explained Acquaint yourself with the different zones of a non-luminous flame (Fig. 8). Which zone of the flame is the hottest  

Many structural adhesives require heat as well as pressure to cure. Even with conventional room temperature curing systems, most often the strongest bonds are achieved by an elevated-temperature cure. With many adhesives, tradeoffs between cure times and temperature are permissible. Generally, the manufacturer will recommend a certain curing schedule for optimum properties. 

If a cure of 60 min at 150°C is recommended, this does not mean that the assembly should be simply placed in a 150°C over for 60 min. The temperature is to be measured at the adhesive bond line. A large part will act as a heat sink and may require substantial time for the adhesive in the bond line to reach the necessary temperature. In this example, total oven time would be 60 min in addition to whatever time is required to bring the adhesive up to 150°C. Bond line temperatures are best measured by thermocouples placed very close to the adhesive. In some cases, it may be desirable to place the thermocouple in the adhesive joint for the first few assemblies being cured. 

Both induction and dielectric heating involve relatively expensive capital equipment outlays, and the bond area is limited. Their most important advantages are assembly speed and the fact that an entire assembly does not have to be heated to cure only a few grams of adhesive. 

Plastics Compounding, 1991-1992 Redbook, Edgell Communications, Inc., Cleveland, OH. 

Devlin, W., Metering and Mixing Equipment, in Adhesives and Sealants, vol. 3, Engineered 

A cheaper but less controllable device for steady evaporation of acids to dryness is the air bath shown diagramatically in Fig. 3. It consists of an aluminium sheet box with the vertical sides insulated with Sindanyo sheet. The bottom is open and rests on an ordinary hot plate. The top is drilled to hold test-tubes suspended by the rims. The temperature can be controlled by judicious use of the hot plate control for the gentle evaporation of 

The repetitive measuring of small ( 20cm3) volumes of liquid is best undertaken by means of equipment such as the Oxford all-glass dispenser (The Bohringer Corporation Ltd., Bell Lane, Lewes, Sussex BN71LG, U.K.). Even concentrated nitric acid or perchloric acid can be permanently kept in such a device, the volume dispensed is remarkably precise, and the action very rapid. Other manufacturers equipment may be suitable but those with metal parts (such as springs) must be avoided because of the inevitable corrosion caused by acid fumes. No dispenser suitable for hydrofluoric acid has yet been found. 

In geochemical analysis the concentration range of an analyte often spans several orders of magnitude, and dilutions are frequently required to bring the sample solution within the calibration range. An automatic variable-ratio diluter is essential for this purpose. Many manufacturers produce suitable models, but corrosion problems are almost inevitable with the acidic solutions which are regularly used. Small amounts of acid can escape between the piston and the barrel, and cause corrosion, especially where metal parts are enclosed. 

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Based on these considerations, the conformity assessment tables comprise 4 tables for vessels and 4 tables for piping. A further table relates to fired or otherwise heated equipment. Specific procedures are set out for the assessment of assemblies and of safety accessories. 

Induction heating equipment installations can require significant investment in electric power components as well as the work handling equipment made necessary by the process. These costs can be offset by savings in plant space, reduction in metal loss, precise control of product temperature, and reduced in-process inventory. A typical continuous induction heating line consumes about 360 kW h/t heating carbon steel bars to 1230°C. 

Correct selection of heating equipment and zoning of electrical equipment to reduce the chance of an ignition source arising. 

Air conditioning and warm air heating equipment and oommercial and industrial refrigeration equipment... 

Improper use or poor maintenance of portable torches, boilers, driers, and portable heating equipment comprise tliis source of ignition. 

Most new gas and oil-fueled furnaces and boilers have similar efficiencies. The range of efficiency has narrowed with the introduction of minimum efficiency standards for new products sold since 1992. New gas and oil heating equipment currently available in the marketplace have /knnual Fuel Utilization Efficiency (AFUE) ratings of at least 78 to 80 percent. /VFUE is a measure of how efficient a furnace operates on an annual basis and takes into account cycling losses of the furnace or boiler. It does not include the... 

Barbour, C. E. Dieckinann, J. T. and Nowicki, B. J. (1996). Market Disposition of Higb-Efficiency Water Heating Equipment, Final Report, edited by U. S. D.o.E. Office of Binding Equipment. Washington DC Aithur D. Little, Inc. 

Gas Appliance Manufacturers Association. (1998). Consumers Directoiy of Certified Efficiency Ratings for Residential Heating and Water Heating Equipment. Arlington, VA GAMA. 

Table 27.13 Characteristics of water system heating equipment...

At its simplest, a HW heating cycle is the circulation of HW from a boiler (or heat pump or similar device) through a supply and distribution piping system to various appliances and then back to the boiler. Hot water systems are hydronic systems and, when of any size, are designed to operate via various primary and secondary circuits. These circuits are provided with their own circulating pumps of different capacities to provide proper layout flow, usually to perimeter-wall m-tube convectors, fan coil units, or other space heating equipment. 

Other heating equipment. Autoclave used for sterilization can be used to achieve superheating condition at 120°C. For higher temperature heating, a domestic pressure cooker, or a plastic steamer may be used. Some commercial laboratory pressure cookers have been designed for AR-IHC with controlled temperature. A water bath can be used to achieve lower temperature heating condition. 

To maintain a heating condition under boiling point such as 98°C, a laboratory water bath with controlled temperature, or other heating equipment that may provide lower temperature heating condition may be adopted. 

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