Is there specific guidance where a particular zone starts, or is the whole booth regarded as one zone?
We are a joinery company and have a booth with a 3.0m wide dry back extract for lacquer finishing. Our insurance company has raised concerns regarding the zoning within the room.
In both the US and Europe the interior volume of a spray booth is considered to be a single area classification.
In the US, NFPA 33 Standard for Spray Application Using Flammable or Combustible Materials 2011 Edition, provides guidance on the electrical area classifications in and around a spray booth. It states that the interior of a spray booth or spray room is considered Class I, Division 1. The external volume within 915 mm (3 feet) of openings, including closed doors, is Class I, Division 2. Chapter 6 provides diagrams for the various styles of booths as well as for open spraying.
In Europe, the standard is EN 12215 Coating plants – Spray booths for application of organic liquid coating materials – Safety requirements. In the 2009 Edition, the Zone classification is based upon the concentration of flammables. It states that if you are between 25% and 50% of the LEL, then the interior of the spray booth is Zone 1. If you are less than 25% of the LEL, then the interior is Zone 2. In all cases, the external volume within 1 m of permanent openings is classified Zone 2. This information is taken from Section 22.214.171.124 and Figures A.1 and A.2.
In addition to following industry codes and standards, we recommend that you consult with the local authority to ensure you are in compliance with local codes and standards.