Heating the Paint Booth
OSHA requires the working compartment of a spray booth be maintained at a minimum temperature of 65 degrees Fahrenheit. To meet this regulation, it is mandatory that a heated air make-up unit be used during the winter months in most areas.
In addition, many coatings require a heat-enhanced curing period (bake cycle) after application to reach their final finished state. This heat is applied through a heater or burner unit.
Types of Heaters
There are two types of process heaters: indirect-fired and direct-fired. With an indirect-fired process heater, combustion gases do not mix with or exhaust to the atmosphere from the same stack or vent with gases emanating from the process or material being processed. With a direct-fired process heater, combustion gases mix with and exhaust to the atmosphere from the same stack or vent with gases originating with the process or material being processed.
Indirect-fired units are used in situations in which direct flame contact with the process material is not desired, mainly because of the risk of contamination and ignition of the material. Emissions to the atmosphere from indirect-fired process heaters are generic to the fuel in use and are common across a wide range of industrial sources.
Direct-fired units are used where such problems are not a factor. Emissions from indirect-fired units consist entirely of products of combustion. Meanwhile, emissions from direct-fired units consist of both products of combustion and emissions of the process material. Emissions from direct-fired units are unique to the given process and may vary widely, both within a given industrial process (if the process material is changed) and between industrial sources (where widely varying process materials may be handled).
Do direct-fired burners pollute the atmosphere or cause health issues for workers? While a direct-fired burner comes in direct contact with the outside air being heated to replace the air exhausted from a facility or paint booth, these burners are designed to ensure they burn as clean as possible and the products of combustion meet safety requirements. In addition, burners are tested by an independent testing laboratory to ensure compliance with the American National Standards Institute (ANSI).