sprinklernotes
Air Receivers
The following information was provided: Three large dry pipe systems are
supplied by a 3-horsepower base mount compressor. Each system utilizes an air
maintenance device with an individual pressure switch (AMD-2) tied to the
single air compressor. The compressor will fill all three systems if the
system air pressure is lower than the cutoff pressure of the system, which is
calling for pressure.
You asked the following question: Should a tank-mounted air compressor be
utilized using regulated air maintenance devices (AMD-1) at each of the dry
pipe systems?
The following is in response to your question(s) based on AFSA’s Technical
Review of NFPA 13, Standard for the Installation of Sprinkler Systems, 2022
edition.
A base-mount air compressor can be utilized if the air supply has an air
receiver maintained at a pressure higher than the system pressure installed.
Each dry pipe system must have a listed regulator-controlled air maintenance
device (AMD-1) as well.
A tank-mounted air compressor would also suffice as the tank itself is an air
receiver. Pressure-regulated air maintenance devices (AMD-1) would still need
to be installed to maintain the pressure of each dry pipe system.
The NFPA 13, 2022 edition states:
3.3.2 Air Receiver. A chamber, compatible with an air compressor, that can
store air under pressure that is higher in pressure than that in the dry pipe
or preaction system piping. (AUT-SSI)
8.2.6.6.1 Unless the requirements of 8.2.6.6.2 are met, where the air supply to
a dry pipe system is maintained automatically, the air supply shall be from a
dependable plant system or an air compressor with an air receiver, and shall
utilize an air maintenance device specifically listed for such service and
capable of controlling the required air pressure on, and maximum airflow to,
the dry pipe system.
This air receiver can be as simple as a section of a larger diameter pipe
leading to the air maintenance device. Similar language can be found back to at
least the 2002 edition of NFPA 13.
