Your Questions, Answered — Crossdraft Paint Booth Airflow & Electrical Safety

Q: What are the regulations regarding intrinsically safe electronic devices inside a paint booth?  If allowed, what type of certification and enclosure does a communications device require to go into a paint booth?

A: The interior of a paint spray booth or room must meet the requirements for a Class 1 Division 1 area as defined by NFPA 33 Standard For Paint Spray Booths and NFPA 70 – Article 516 National Electrical Code. Intrinsically safe circuits are allowed in this area but must meet the requirements of NFPA 70 – Article 504 Intrinsically Safe Systems.

PQ Booth_boatinQ: What type of spray booth is best, a traditional crossdraft where the air moves front to back, or a reverse flow where the air moves from the back to front?

A: GFS Industrial Territory Manager Dave Rohland offers this response:

“In my opinion, a reverse flow is a better design than a standard cross flow. The reason I state that is as follows.

“With a reverse flow design, the product entry/exit doors are located at the exhaust end of the booth. If there is any unfiltered plant air that enters the booth through the product doors due to leaks, bad seals etc., it is drawn directly to the exhaust filters instead of being drawn down the entire length of the booth like what happens with a standard cross flow booth.”

Q: We are a joinery company and have a booth with a 3.0m wide dry back extract for lacquer finishing. Our insurance company have raised concerns regarding the zoning within the room. Is there specific guidance where a particular zone starts or is the whole booth regarded as one zone?

A: 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 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.

More Information:

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