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Gilberts (Blackpool) Ltd
High Performance Louvre Selection - WH Series
Table 1
In order to effectively size a high performance louvre one must
firstly establish the parameters that are important to the system
design. These may be:
a) Maximum pressure drop through the louvre as
calculated from Table 1.
b) Maximum effectiveness based upon a wind
velocity of 13m/s established from Table 2.
Example
If the maximum pressure drop that can be
accommodated is 16 Pa, then the ventilation rate per m² of louvre
area that can be handled from Table 1 would be 1.5m³/s.
If this is now related to Table 2 the
effectiveness of the louvre would then be 98%.
Example 2
If the effectiveness or water repellent nature of
the louvre is paramount and a 99% efficiency is important, then from
Table 2 a 1m/s face velocity or 1m³/s per square metre of louvre
area would be the maximum volume that can be accommodated. This
would then give a pressure drop from Table 1 of 7.5 Pa.
Classification
From the New European Standard EN 13030, louvres
will be classified using both the COEFFICIENT OF ENTRY or DISCHARGE
(CE or CD) and a water penetration rate.
Classifications are as follows:
The water repellent classification is denoted by
the following chart:-
ie. 0.99 EFFECTIVENESS = 99% water repellent
efficiency.
The combined classification would have the water
repellent class reference first followed by the coefficient of entry
or discharge i.e.
A - 2 (up to 1m/s face velocity)
Example Louvre Sizing
Required louvre with an effectiveness of no less
than 0.99 and a maximum pressure drop of 16 Pa.
Total Intake Volume 5m³/s
From Table 2 maximum ventilation rate per m² of
louvre area that will give 0.99 effectiveness = 1m³/s.
From Table 1 pressure drop = 7.5 Pa, which is
below the maximum requirement. Therefore, louvre area required = 5/1
= 5m FACE AREA
Alternative
If an effectiveness of 0.98 would suffice, then
from Table 2 a volume of 1.5m³/s per m² face area would be allowed.
This would give a pressure drop of 16 Pa.
Therefore, new louvre size would be:-
5 = 3.33m² FACE AREA
1.5
Penthouse Louvres
For Penthouse louvres the face area of all sides
should be calculated and the addition related to the above
calculations for total face area.
Test Results
All Gilberts louvres have been subject to
simulated weather conditions on the BSRIA Test Rig, which follows
the requirements and specification of the new European Standard
EN13030. All graphs and information are developed from test results.
The WH/75 louvre assemblies have a CD/CE of
approximately 0.3
WP/75 louvre assemblies have a CD/CE of
approximately 0.27
WH/75 = Class A2 up to 1 m/s
WP/75 = Class B3 up to 0.5 m/s
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