If allowed, what type of certification and enclosure does a communications device require to go into a paint booth? National Fire Protection Association The interior of a paint spray booth or room must meet the requirements for a Class 1 Division 1 area as defined […]
There is no code or standard that requires a specific air change for paint spray booths. It is more common for the ventilation performance of a spray booth to be specified by the average velocity through the booth or in the vicinity of the painter and product. From the design velocity you can calculate ventilation flow rates and air changes.
For example, if your booth is 16 feet wide by 14 feet tall and is a crossdraft design, typical velocity in the booth would be 100 feet per minute (fpm). The total flow through the booth would be 22,400 cubic feet per minute (CFM) (16 x 14 x 100). The volume of the booth is 8960 cubic feet (16 x 14 x 40). The air changes can be calculated by dividing the flow rate by the volume. In this example, the air changes would be 2.5 air changes per minute (22400 / 8960).
However, if this is a downdraft booth, typical velocity in the booth would be in the 50 to 100 fpm range. For this example let’s use 50 fpm. In this case, the total flow through the booth would be 32,000 CFM (16 x 40 x 50). Dividing the flow by the volume of the booth would give 3.5 air changes per minute (32000 / 8960). The velocity is half that of the previous example, but the air change is higher.
From a fire safety standpoint, NFPA 33, Standard for Spray Application Using Flammable or Combustible Materials 2011 Edition and the 2012 Edition of the International Fire Code both require that the ventilation rate shall be able to maintain the concentration of flammable vapors in the exhaust below 25 percent. So the minimum ventilation flow rate is a function of how much paint is being sprayed and the volume of flammable materials in the paint. After establishing this minimum, the ventilation rate may be increased in order to maintain a minimum average velocity through all openings to prevent the escape of overspray from the spray booth and to achieve the desired collection of overspray toward the exhaust filters.
What is the best placement of sensor tubes coming from the magnahelic gauge for a downdraft paint booth?
Measuring Pressure The answer depends on what pressure differential you are trying to measure. If you are measuring cabin pressure compared to building pressure, the high-pressure sensor tube should be mounted in the cabin away from any booth openings. The low-pressure tube should be left […]
National Fire Protection Association A means is required to make sure that you are moving the required amount of air for paint spraying. Your choices depend upon the code or standard adopted by your local authority. If NFPA 1 Fire Code is being enforced then […]
Regardless of the filter used, it is a matter of how much total resistance is designed into the fan in question and the relative condition of the fan. All fan units are designed to operate within a range of resistance, that includes the ductwork, plenum […]
We would like to turn down the airflow in our spray booth during non-spraying times (i.e. warming it up in the morning).
There is no specific airflow requirement for non-spraying modes such as prep or unoccupied times. Generally, users will revert back to standard building design which is 6-8 air changes per hour. This would be enough to keep the temperature in the booth. This may be complicated slightly by the size of the air handling equipment on the booth though. You may be limited to the available turndown of the booths fans which will determine the minimum airflow that the system can handle. Generally, we are limited to 30-50 percent. Saying that if a fan is designed for 10,000 CFM, the most we could turn it down would be 3,000 to 5,000 CFM.
Code Compliance: Only one of the standards (EPA’s 6H Rule) that we see applied to spray booths addresses booth pressure specifically. One of the purposes of a spray booth is to confine and capture the overspray. While the spray booth’s ability to do this may […]