Safety Tidbit 3.24 - Spray Booth Ventilation

Safety Tidbit 3.24 – Spray Booth Ventilation

Reference: Spray Finishing using Flammable and Combustible Materials

Lately, it seems that I have been noticing spray booths with a build-up of overspray. As I look closer at spray booths, I find insufficient ventilation, poor paint application practices, or just too many parts for the size booth. I can talk to the painter about their practices and help with the client’s flow of materials through the enclosure to reduce the paint overspray problem. However, what concerns me is when there is an insufficient airflow in the booth. Lack of ventilation is a potential health concern.

How many of you have seen a spray booth when turned on the motor makes a lot of noise, but there is only a negligible movement of air? Or, the airflow is out of the booth versus into it? Minimally, OSHA [1910.107(b)(5)(i)] requires “spraying operations shall be so designed, installed and maintained that the average air velocity over the open face of the booth (or booth cross section during spraying operations) shall be not less than 100 linear feet per minute.” So, naturally, I ask the question “when was the last time you checked the airflow for the booth?” Unfortunately, I usually get blank stares.

Next, I ask, is the booth equipped with a gauge? The second part of the minimum OSHA standard requires “visible gauges or audible alarm or pressure activated devices shall be installed to indicate or ensure maintenance of the required air velocity.” Often, I got a nod and shown a manometer on the side of the booth. Sometimes, they even have it marked with a note telling the worker to change filters when the pressure reaches a certain level. Unfortunately, there is no indication on the gauge telling them when the booth is operating correctly. I have seen indicators that register zero (meaning no change in static pressure across the filters) when the enclosure is in operation. If there is no change in static pressure across the filters are the filters doing their job?

A better design would be to have a vaneometer installed in addition to the manometer, so airflow can quickly and accurately be determined. Furthermore, periodically performing a thorough evaluation of the airflow across the entire cross-section of the booth is a prudent practice. An industrial hygienist can help out with this. Ultimately, if the client complies with the last part of the OSHA standard “filter rolls shall be inspected to ensure proper replacement of filter media” the airflow should be even across the booth opening. Provided they don’t have “stuff” blocking the airflow. Hmm, never saw that either…J

Hope this was helpful and thanks for reading my Safety Tidbits! Comments and questions are always welcome. ~ Bryan

P.S. If you have an interesting safety or health question please let me know.