The NFPA standard that deals with air conditioning and ventilating systems is NFPA 90A. NFPA 90A is the standard for the installation of air conditioning and ventilating systems.
NFPA 90A covers the installation, inspection, and maintenance of air conditioning and ventilating systems. It ensures that these systems are installed, inspected, and maintained to prevent fires and ensure safe operation.
NFPA 90A is a critical standard for building owners, architects, engineers, and contractors. It provides guidelines for the design, installation, and operation of air conditioning and ventilating systems.
NFPA 90A is regularly updated to reflect changes in technology and safety standards.
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NFPA Standards for Air Conditioning and Ventilating Systems
The NFPA 90A and 90B standards cover fire safety and referenced material standards for air conditioning and ventilating systems.
The scope of NFPA 90B is identical to NFPA 90A, but it addresses HVAC heating systems, one or two-family dwellings, and spaces not greater than 25,000 ft3 in volume.
To meet NFPA 90A and 90B standards, Aeroflex's Aeroflex brand of EPDM closed-cell elastomeric foam pipe and duct insulation must pass ASTM E84 25/50 and ASTM C411 with a maximum continuous service temperature threshold of 257°F (125° C).
Duct detectors should be installed in a way that allows verification of airflow from the duct to the detector, and should be located where air enters or leaves the duct system.
NFPA 90A vs 90B
The scope of NFPA 90B is identical to NFPA 90A with respect to fire safety and referenced material standards. NFPA 90B specifically addresses HVAC heating systems, one or two-family dwellings, and spaces not greater than 25,000 ft3 in volume.
One important differentiation to point out is the type of closed-cell foam insulation that complies with NFPA 90A/90B. PE-type insulation, also known as polyethylene, must pass both ASTM E84 and ASTM C411 to meet the requirements.
Aeroflex’s Aeroflex brand of EPDM closed-cell elastomeric foam pipe and duct insulation meets the requirements of NFPA 90A and NFPA 90B by passing ASTM E84 25/50 and ASTM C411 with a maximum continuous service temperature threshold of 257°F (125° C). This is a key consideration for anyone looking to install this type of insulation in their HVAC system.
NFPA 90A Duct Detector Requirements
NFPA 90A duct detector requirements can be a bit confusing, but don't worry, I've got you covered. Detectors should be located where air enters or leaves the duct system.
To meet NFPA 90A standards, detectors should be installed in a way that obtains a representative sample of the airstream. This means you need to verify airflow from the duct to the detector.
Duct-mounted smoke detectors are required downstream of all filters, but upstream of all branch takeoffs for supply fans with capacities greater than 2,000 cfm. The same goes for return fans with a capacity greater than 15,000 cfm.
In multi-story buildings, duct-mounted smoke detectors are also required in each return duct inlet that serves more than one story for systems with a capacity of greater than 15,000 cfm. These detectors should be able to sense smoke on a particular floor.
Duct-mounted smoke detectors, however, are not required in a return air system if the spaces served by the HVAC system are protected by ceiling-mounted smoke detectors.
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Integrate Systems
Integrating all the systems is a crucial step in ensuring your air conditioning and ventilating systems meet the necessary standards. Superimposing HVAC infrastructure on architectural and structural systems is where the fun begins.
Protection of duct, pipe, and conduit penetrations in fire-rated walls and partitions, floors, roof-ceiling assemblies, shafts, and smoke barriers is a focus of NFPA 90A. The standard includes a handy diagram outlining a couple dozen of the most common penetrations in these building components.
Fan rooms need to comply with all requirements, especially if they house fan systems serving multiple floors with ducts routed into vertical shafts. Standard 90A dictates which ducts can share shaft space with each other.
For example, kitchen exhaust duct risers cannot be installed in the same shaft as supply and return air duct risers. Note that when this situation is met in an existing building, there are techniques that can be implemented to achieve separation without having to reconstruct shafts and duct risers, including special duct wraps for kitchen exhaust duct risers.
Duct-mounted smoke detectors are required downstream of all filters, but upstream of all branch takeoffs for supply fans with capacities greater than 2,000 cfm. The same goes for those of return fans with a capacity greater than 15,000 cfm.
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