There are a variety of reasons we collect overspray prior to exhausting air from a spray booth. Those reasons tend to fall into four broad categories: mechanical, worker-safety, environmental compliance, and finish quality. Let’s take a closer look at these categories.
By collecting overspray rather than discharging it, you are ensuring protection for your spray booth investment. With proper ventilation and collection of combustible vapors and solids, you reduce the buildup of errant overspray on the booth walls, ducts, and fan. That buildup of overspray will reduce the overall air velocity (CFM) and increase the amount of energy required to operate the system. It will also increase the wear on your booth and lead to frequent maintenance and repairs. Many large finishing operations now utilize abatement systems to control VOCs. Failure to remove solid contaminates prior to reaching the abatement system could cause irreparable damage.
The NFPA (National Fire Protection Association) guide NFPA33 “Standard for Spray Application Using Flammable or Combustible Materials” offers a comprehensive list of standards for spray booth construction and use. Learn more here: www.nfpa.org.
A properly ventilated spray booth ensures the consistent removal of flammable and hazardous vapors and solids. Collecting those solids reduces the buildup of flammable overspray and the likelihood of a combustion event. A well-balanced overspray collection system will also improve air velocity and provide a cleaner work environment for spray booth operators.
OSHA (Occupational Safety and Health Administration) standard 1910.107 “Spray finishing using flammable and combustible materials” lists detailed requirements for worker safety in and around spray booths.
Spray booth exhaust and the related overspray collection may be governed by NESHAP (National Emissions Standards of Hazardous Air Pollutants). Additionally, your emissions may also have local or state regulations that govern the amount and type of collection required for your process. Many common finishing applications are guided by EPA Standard 40 CFR Part 63. This requires a minimum removal efficiency of 98%. In addition to regulatory requirements, failure to capture overspray can result in damages to the outside environment environment including build of overspray on cars, buildings, and nearby private property.
Overspray that is not properly collected could remain airborne in the spray booth or recirculate back through the air make up unit. This overspray may be semi-cured and considered “dirt” or a “contaminate.” If this overspray lands on the target product it could result in a blemish or surface defect thus requiring costly rework or a full replacement.
Proper overspray collection is an often overlooked process in finishing applications. It is imperative that spray booth operators consider the safety and environmental implications of their exhaust filtration and balance those with the mechanical and quality control requirements of their application. There are many types of overspray collectors to choose from. Filtration Group Finishing offers a large array of products for virtually every spray booth design. Our technical sales team is prepared to match the best available technology to your finishing needs.
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By Brian Smith, VP of Sales/Marketing – Filtration Group Finishing