ASHRAE Journal - ACMA Supplement - Fall 2013 - 14

alternatively, 50 mph with a rain fall rate of 8 in./hr. When under
test, water is injected into the 29 mph or 50 mph air stream and
driven toward the louver while a simultaneous intake velocity
is drawn through the louver. At each given intake velocity an
elimination percentage is established based on how much of the
applied water passes through the louver.
Although both of these tests are adequate for specifying louvers
that provide adequate water protection in most areas of the
country, neither can determine how a louver will perform when
impacted with the wind and water produced by hurricanes.
To provide building protection during a hurricane event, louvers
must be capable of removing enormous amounts of water from
the system air stream. If a louver with high water performance
is not used, a damper must be located behind the louver and it
must be closed during the event; otherwise, large amounts of
water will penetrate the building and damage the interior.
ANSI/AMCA 550 Explained

ANSI/AMCA 550 evaluates louvers for water penetration
at wind speeds of 35 mph, 70 mph, 90 mph and 110 mph –
speeds that accurately reflect hurricane events. The rainfall
rate used during the test is 8.8 in/hr. The procedure for the test
is based on Testing Application Standard (TAS) No. 100(A)
Test Procedure for Wind and Wind Driven Rain Resistance
and/or Increase Windspeed Resistance of Soffit Ventilation
Strip and Continuous or Intermittent Ventilation System Installed
at the Ridge Area (TAS 100A). TAS 100A establishes “the
resistance to wind driven rain of a continuous or intermittent
ridge area ventilation system . . .” The Miami-Dade Building
Code Compliance Office (BCCO), which promulgates building
standards for Miami-Dade county in the state of Florida, states,
“louvers installed in a location where the room behind the
louver is not designed to drain water penetrating into the room,
or the room will house non-water resistant equipment, components, or supplies, the following test (TAS 100A) shall be
performed.” To accommodate this requirement, the BCCO

issued a modified TAS 100A procedure for louvers under
Checklist #0240.
The procedures for AMCA 550 and TAS 100A are virtually
identical; the main differences are the pass/fail criteria. The
TAS100A test required that no water infiltration was allowed at
the 35 and 70 mph wind speeds. This requirement proved to be
unrealistic for wall-mounted louvers because even trace amounts
of water passing through the blades would result in product
failing the test. The BCCO reviewed AMCA 550, and determined
it is acceptable as an alternative test procedure to TAS100A.
During the AMCA 550 test, the louver sample to be tested is
mounted in a block wall. A chamber is mounted behind the
louver to collect water that passes through the louver. The collection chamber is open at the top to allow the passage of air.
During the test, water is injected into the air stream at the specified wind speeds at a rate of 8.8 in./hr, as shown in Figures 1
and 2. The total volume of water applied over each test interval
(Table 1) is measured and recorded. No intake air is drawn
through the louver. The test duration is 15 minutes at each
required velocity followed by a 5-minute period with no spray
and no wind. At the conclusion of the 20-minute period, the
water passing through the louver is measured. If the amount of
water collected behind the louver is in excess of 1% of the total
volume of water applied to the louver for the test period, the
louver fails the test.
Code Requirements for AMCA 550

The 2012 International Mechanical Code and the 2010 Florida
Mechanical Code currently require louvers that have passed the
AMCA 550 test for intake openings in hurricane prone regions.
The 2012 International Mechanical Code states:
“401.5 Intake opening protection . . . Louvers that protect
air intake openings in structures located in hurricane prone
regions, as defined in the International Building Code, shall
comply with AMCA 550.”
Interval Wind Speed
#
mph (m/s)

Time
(min.)

Water Spray

OFF

70 (31.3)

OFF

90 (40.2)

OFF

110 (49.2)

Fall 2013

Figure 2 – AMCA 550 testing assembly. Image courtesy of Ruskin.

35 (15.65)

OFF

Test Result

<1% of the water applied
in interval 1
<1% of the water applied
in interval 3
<1% of the water applied
in interval 5
<1% of the water applied
in interval 6

Table 1 – AMCA 550 test intervals.

AMCA I n t e r nat i o na l

inmotion

w w w. a m c a . o r g

http://WWW.AMCA.ORG

ASHRAE Journal - ACMA Supplement - Fall 2013

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