Greenheck Fan Understanding Sones and DBA for Ventilation Systems

Things to know,
when sound is critical		®
Sound Data
	SUGGESTED LIMITS FOR ROOM LOUDNESS
The sound data shown in this catalog has been
	Sones	DBA
presented to aid the system designer in selecting a
	1.3-4	32-48 Private homes (rural and suburban)
fan which will meet the desired sound criteria. Sone	1.7-5	36-51 Conference rooms
levels have been included on the performance pages	2-6	38-54 Hotel rooms, libraries, movie
		theatres, executive offices
to provide a means of quickly evaluating the relative	2.5-8	41-58 Schools and classrooms, hospital
loudness of a fan selection.		wards and operating rooms
	3-9	44-60 Court rooms, museums, apartment
What is a sone?		houses, private homes (urban)
	4-2	48-64 Restaurants, lobbies, general open
Sones are an internationally recognized unit of loudness. In		offices, banks
	5-15	51-67 Corridors and halls, cocktail
practical terms, the loudness of one sone is equivalent to the
		lounges, washrooms and toilets
sound of a quiet refrigerator measured from five feet away	7-21	56-72 Hotel kitchens and laundries,
in an acoustically average room. A sone is a single number		supermarkets
	Reprinted from AMCA Publication 302 (Application of Sone
rating, which indicates the inlet noise derived from the eight
	Ratings for Non Ducted Air Moving Devices, with room—sone—
audible octave bands. Sones are a linear measurement of
	dBA correlations) with the written permission from the AMCA
sound level. For example, a sound level of 10 sones is twice	International, Inc., 30 West University Drive, Arlington Heights, IL
	60004-1893.
as loud as 5 sones.
	NOTE: Values above are for room loudness and are not sound
What is the difference in a AMCA Sone vs. HVI Sones?	ratings. Room loudness is the resulting level in a conditioned space
	after the acoustical qualities of the room have been accounted for.

In general, the AMCA (Air Movement and Control Association) sone value is focused on commercial markets, whereas the

HVI (Home Ventilating Institute) sone value is focused on residential markets. Both calculate their sone data from the same raw test data (eight octave bands), however an AMCA sone applies a hemispherical correction factor to the sound power and rounds to the nearest 0.1, whereas HVI applies a spherical correction factor to the sound power and rounds to the nearest 0.1 under 1.5 sones and to the nearest 0.5, 1.5 sones and greater. There are no conversions from one sone to the other, each must be calculated. In every instance the same fan will have a lower HVI calculated sone rating than an AMCA calculated sone rating.

Can radiated noise increase the sound levels?

Radiated noise from fan housings can cause unacceptable sound levels, on any brand of fan. The size of these fans allows them to be placed in areas where this noise will be transmitted to the conditioned space through walls or ceilings. Where possible, cabinet fans should be located in remote parts of the ventilation system.

When should a SP or CSP fan be used?

Model SP and CSP fans are designed for the lowest possible sound levels. Forward curved wheels, insulated housings, and vibration isolators between the motor and housing contribute to quiet, efficient operation. Applied and installed as recommended, SP and CSP sound levels will fall well within the ranges shown in the chart above. For applications where sound levels are critical, a remote mounted CSP with ductboard is

recommended. Placement of SP/CSP fans should take into account the desired sound level at the location of
the listener. Their compact size allows the system
designer greater flexibility in locating these fans for
lowest sound levels. In critical sound areas, insulated	Fiberglass
ductwork, flexible duct connections, or placing the
fan in a remote section of the ductwork (away from	Remote mounted
the critical area) offers the best means of meeting
	Model CSP with
desired sound levels.	vibration isolators and
	insulated ductwork
When room sound levels are critical, such as in
	provides quietest
executive offices, conference rooms, hospital	installation.
operating rooms, and school study areas, a CSP
fan is the best choice. Shown here is a comparison
of SP and CSP fans of the same size, with equal
performance in typical installations. The CSP shows
lower sone values.

Model	CFM	WG	FRPM	Sones
SP-A410	405	1/8	1000	3.7
CSP-A410	426	1/8	1000	2.1*

*Sone value with insulated inlet duct.

Model SP mounted directly overhead may be too loud for sound critical applications.

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