FAQs

What are the regulations regarding intrinsically safe electronic devices inside a paint booth?

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? 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 […]

What is the proper way to get an even finish when painting a metallic hood without getting the stripe effect when applying the clearcoat?

What is the proper way to get an even finish when painting a metallic hood without getting the stripe effect when applying the clearcoat?

Finish Application If the stripping is happening only after you start applying the clear coat it is possible that the basecoat is not completely flashed off when the clear in applied. This can cause the metallic to shift. Another possibility is that the basecoat has […]

How many air changes are required for a 16 by 14 by 40 paint booth?

How many air changes are required for a 16 by 14 by 40 paint booth?

Air Changes

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.
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What is the best placement of sensor tubes coming from the magnahelic gauge for a downdraft paint booth?

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 […]

Are manometers or other pressure drop devices required by law on exhaust filters?

Are manometers or other pressure drop devices required by law on exhaust filters?

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 […]

What are the potential hazards when painting with the doors open?

What are the potential hazards when painting with the doors open?

“We are using a spray gun between 20-60 psi when the production doors are open on the unit. Do the filters on the doors provide a significant protection factor when dealing with Isocyanates?”

The paint booth should have the doors closed during paint spraying. The velocity through the filters in the door should keep all vapors and overspray confined to the booth. You should avoid spraying any paint directly at the intake filters.

With the doors open the booth becomes an open face booth. You may need to adjust airflow rates to ensure that you have enough capture velocity through the opening to confine the vapors or overspray to the booth. Typical face velocities for an open face booth range from 100 to 150 feet per minute, but may need to be higher for your application.

If you are concerned about the concentration level of Isocyanates outside the spray booth, we suggest you contact an Industrial Hygienist. They can perform the necessary sampling tests to determine what the exposure levels may be.

How do I maintain a specific spray temperature inside the paint booth?

How do I maintain a specific spray temperature inside the paint booth?

I live in Malaysia with the temperature of 32 degree Celsius, how do I maintain the spray temperature of 23 degrees Celsius inside the painting booth? Do I need to install a chiller and humidifier? Due to the conditions in Malaysia the temperature set-point being […]

Is there a “magic number” on the manometer at which paint booth filters should be changed?

Is there a “magic number” on the manometer at which paint booth filters should be changed?

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 […]

Is there a minimum airflow guideline for non-spraying times?

Is there a minimum airflow guideline for non-spraying times?

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.

What are the code requirements for negative/positive pressure in a paint spray booth?

What are the code requirements for negative/positive pressure in a paint spray booth?

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 […]