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How to determine if a make-up air system is required: It’s simple math

Anytime a paint booth is installed in a building, the amount of exhausted air must be a consideration.

For example, a booth exhausting 13,000 cubic feet per minute installed in a building measuring 50 x50 x 15 (37,500 cubic feet), the air will change every two minutes. This produces a negative pressure condition on the building that can cause safety issues. If the building is equipped with gas-fired unit heaters, the negative pressure condition can actually pull gas from the pilot valves and put raw gas into the room. NFPA-33 addresses this with a calculation.

NFPA-33 A.7.3 “If the volume of the room or building where the exhaust system is located is not at least equal to 20 times the volumetric capacity of the fans (three air changes per hour), then additional make-up air should be provided.”

Going back to the 13,000 cfm exhaust fan. 13,000 x 20 = 260,000 cubic feet. The room would have to be 110’ x 110’x 20’ (264,500 cubic feet).

The rule of thumb is to provide the same amount of air being exhausted with some adjustment in the unit to provide the customer with the proper pressure he requires. Some may want slightly more positive pressure while some may want a neutral pressure building.

Sure-Cure Air Makeup Unit
Sure-Cure Air Makeup Unit

Make-up air units can be placed outside or inside as long as the intake air is drawn from the outside. The control panels are mounted inside the building and can be interlocked to the paint booth to operate simultaneously. If you want more information on the Sure-Cure units from Standard Tools and Equipment, visit us online.

The ductwork is simple, the discharge duct should be equipped with a diffuser to help distribute air more evenly into the room.

If you have any questions, give us a call and we’ll gladly assist in determining if more makeup air is needed. 800-312-7488.

 

 

Why you won’t find a variable frequency drive (VFD) on our unheated booths

We have many customers that ask us if we offer a variable frequency drive or VFD for our paint booths. The answer is simply “No” and we have a very good reason on why.

A variable frequency drive allows you to control the speed of a motor. It is also known to be called a variable speed drive, adjustable speed drive or an adjustable frequency drive. We are very familiar with the VFD because we utilize them on our Air Makeup Units (which controls the exhaust fan on our heated booths – but not the intake fan). The difference is when we control the exhaust fan on the AMU’s, your booth remains in compliance and safe to use.

The VFD can turn the speed of the motor up or down depending on the motors capabilities. Most customer’s request this so they can reduce the speed of the motor for several applications explained, but not fully known to us as a manufacturer.

The simple answer, “No”, is followed by an explanation that if you turn down the motors speed; the booth will not be in compliance with the code requirements. A certain amount of airflow is required to meet the NFPA-33 guidelines.

To explain it a little more clearly, here is what our engineer Tracy Beach has said about this subject:

Insufficient airflow:

* will lead to poor painting quality

* will cause excessive fumes

* may easily lead to a fire or explosion due to flammable fumes not being exhausted from the spray booth. This is not a matter of convenience; the spray booth must be properly exhausted or it is simply a box holding lights and explosive fumes. The ventilation performance of most spray booths designed by Standard Tools is 6-10% above the NFPA-33 and OSHA code requirements.  Decreasing the airflow would be dangerous and may result in poor coating quality since the over spray would not move away from coated surfaces.

We urge our customer’s to contact the local authorities and find out what their cities requirements are prior to making a purchase of our paint booth. Whether it is the building department or fire marshal, we want them to be aware of the requirements. We also offer a paint booth permitting guide to help them along in the process.

Please contact us with any questions or concerns you may have. We are here to help guide you in the decision making process.

Spray Booth Code Requirements

workplace-safetyCODES,CODES, CODES. (Spray Booth Code Requirements). It’s like when you’re in school and it’s always rules, rules, rules. They can be challenging, but we all know that they exist to promote the safe design, production and use of spray booths.  They are what keep the folks working in the booth safe.

The codes are founded on common sense and from incidents from the field, like fires and explosions.

Governmental agencies or third-party groups, like the National Fire Protection Association (NFPA) or Underwriter’s Laboratories (UL), create, administer and enforce the codes.

As a manufacturer of paint spray booths, the codes are very important to us, and everything we do to create the safest work environment for our customer that is possible.

 

THE THREE “C’S” AND HOW WE USE THEM:

Compliant Compliant means that Standard Tools uses the code as the basis in guiding our design, production and documentation.   We meet or exceed the requirements based on our interpretation of the code.

Certified A third-party testing lab like Intertek/ETL tests our booths and compares our production to the code and judges it to meet or exceed the code requirements.  When we pass the testing, we get certification. We label our product, trace the product after it’s sold and go through a routine audit by the NRTL to ensure that Standard Tools continues to comply with the code.

Complete This term means that all of the requirements in the code have been met by Standard Tools.  The NFPA codes for spray booths go beyond the design, production and documentation that Standard Tools provides.  There are requirements within the codes about the location of the spray booth, an adequate air supply and the use of licensed electricians.

With a car, there is a lot of responsibility that falls on the driver. You could have a really safe car, that was manufactured correctly, but if you fail to wear your seat belt, or you drive carelessly, it won’t matter how safe that car was made. It’s the same with a spray booth. A certified spray booth can be installed in an uncertified manner and that negates the entire certification.  There are responsibilities of the spray booth owner.   The owner is required to know and follow the instructions of safe installation and use that is provided with their spray booth from Standard Tools and Equipment.

CODES CORRELATED TO SPRAY BOOTHS
Standard Tools and Equipment is informed on the codes that apply to spray booth manufacturing and use. We understand how intensive and baffling the “code” can be … hey, sometimes we think that it may as well have been written in actual ‘code’ language

because it would seem just as foreign. Here’s a brief snippet of the codes and how they relate to spray booths.

NFPA-33 Spray Application of Flammable or Combustible Materials. This top-level code drives all other codes that are specific about spray booths and mixing rooms.

OSHA 29CFR19 10 Section 94 Ventilation and Section 107 Spray Application of Flammable or Combustible Materials

This is Federal code from OSHA with more detail about actual spray booth performance and how it relates to worker safety.

IFC International Fire Code, Chapter 15
This is an International code with less detail than NFPA-33.  This often applies to spray booths in foreign-trade zones or in businesses owned by International organizations.

EPA’s NESHAP Rule XXXXXX and Rule HHHHHH
This is Federal code that defines maximum air quality emissions for auto body shops and industrial plants relative to spray operations.

State and local codes typically mimic federal codes but may have added requirements for local considerations like weather or seismic issues.

ANSI Z83.4 and CSA STD 3.7
American and Canadian codes relating to direct-fired heated air makeup systems.

UL-508A and CSA STD 22.2 No.1 4
American and Canadian codes relating to electrical control panels.

Canada has no active top-level code for spray booths.  They recognize NPFA-33 and/or IFC Chapter 15.  They do have codes that are specific to the electrical requirements and heated air makeup units.

Codes are not laws.  Codes are enforceable guidelines to be interpreted by authorities such as local permitting agencies, insurance agencies and federal agencies, such as the EPA.  The law is that a spray booth cannot be operated without a final permit to occupy.  The ruling authority provides that occupancy permit based on their judgment of the codes and the spray operation.  Every effort should be made to comply with the codes, but special situations may be permitted if the ruling authority deems the situation as acceptable.

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