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Engineering guide 3 Thermal Processing Technology ENGINEER ? S GUIDE TO EFFECTIVE HEAT PROCESSING Engineer ? s Guide to E ?ective Heat Processing Table of Contents Process Description pg Basic Oven Considerations pg - Heat-Up Soak Cool-down Times pg - Tem

Thermal Processing Technology ENGINEER ? S GUIDE TO EFFECTIVE HEAT PROCESSING Engineer ? s Guide to E ?ective Heat Processing Table of Contents Process Description pg Basic Oven Considerations pg - Heat-Up Soak Cool-down Times pg - Temperature Uniformity pg Processes Involving Flammable Solvents pg Material Handling pg Types of Air ow pg Oven Loading Openings pg Heating Cooling Systems pg Atmosphere Type pg Design Considerations for Ovens in Hazardous Areas pg Electrical Requirements pg Process Control and Monitoring pg - Floors pg Oven Construction pg Facility Considerations pg Testing and Proving Your Process before an Equipment purchase is Made pg Insurance Requirements pg Safety Issues pg Glossary of Terms u Backwelded Seams A method of joining sheet metal panels by welding seams on the backside u Conduction The transfer of heat through a material by passing it from molecule to molecule u Dry Bulb Temperature of air as determined by a standard temperature sensor u Dwell Time Refers to the amount of time that the product spends in the oven While dwell time can refer to batch-type ovens it is most often used with regard to continuous ovens where the product is conveyed into and out of the oven within speci ?c time intervals u Exhaust Volume The amount of air leaving an oven system either passively or forced u Forced Exhaust Process air removed from an oven by an exhaust fan u Load Con ?guration The way in which the parts to be processed are situated in the oven u Lower Explosive Limit LEL Lower Flammable Limit LFL The point at which process air containing solvents becomes explosive ammable u Purge Timer A settable device that times the replacement of air in an oven with fresh air or an inert gas u Radiant Heat A mode of heat transfer in which heat is transferred in a straight line from an emitting surface without signi ?cantly heating the intervening space u Setpoint Temperature An operator controlled variable The desired temperature level of the oven selected as a numeric value on the control instrument u Soak The amount of time that a part or component spends at a given processing temperature u T emperature Strati ?cation Variation in air temperature across a cross- section of air due to uneven mixing of the air u T emperature Uniformity Variation measured in active work space or in air ow entering work area generally de ?ned as ?? X ? spread u T hermocouple A temperature sensor made of two dissimilar metals welded at the measuring junction A millivolt signal proportional to the temperature di ?erence between hot and cold junctions is produced u Wet Bulb Temperature of air as determined by a temperature sensor with a wet wick The relationship between wet bulb and dry bulb temperature readings is a measure of the water vapor in the air About This guide discusses general issues related to the selection of industrial equipment for heat processing Since nearly all products manufactured today require heat