Louvers Engineering Guide - Price Industries

1 Louvers Engineering Guide Selecting the Right louver When selecting a louver , there are sev- First consideration: eral factors that should be considered: FREE AREA. a) Architectural considerations The minimum area through which air the louver height approaches 3 to 4 times b) Location can pass within a louver is called the the louver depth. Since the head and c) Performance free area of a louver1. sill of a louver are of a fixed height, the The free area of a louver is critical space they occupy becomes important, to its overall performance and must thus reducing considerably the amount a) Architectural considerations: of available blade face area (and thus Louvers can be built in multiple sec- be considered during its selection process.

2 Free area). As an example, a 48 x 48 . tions with visible mullions both verti- x 4 deep louver may have of cally and/or horizontally or they can The free area has a direct effect on free area (55%), a 48 x 12 of the same be built in a continuous blade method the air velocity though the louver : less model would have (37%). As (CB) offering an uninterrupted blade free area creates higher air velocities a general rule, avoid selecting a louver line. They can also be built into a pent- thus a higher pressure drop. For intake when its height is less than 4 times its house with mitered or box corners.

3 Conditions, higher air velocities equal depth. The actual free area should b) Location: higher water penetration. always be checked when designing a When Louvers or penthouses are Everything being relative, this is true louver below 48 in height. When the installed at ground level where they for all types and models of Louvers . louver height exceeds 48 , the percent- can be subject to physical abuse, Whenever free area percentages are age of free area will increase slightly. consideration should be given to used always state the louver size on their structural strength.

4 In these which it was calculated. (Published cases, steel or heavy 8 ga. aluminium free area data is based on 48 X 48 . construction should be considered. louver ) 1 AMCA PUBLICATION 501-93, Applica- c) Performance: tion Manual for Air Louvers When discussing performance, four Although it is evident that free area major topics must be considered: varies with louver size, when a louver is selected for a low height application, the free area drops much faster than expected. This effect is most drastic as Engineering Guide - Louvers .

5 3. Copyright Price Industries 2016. All Metric dimensions ( ) are soft conversion. Imperial dimensions are converted to metric and rounded to the nearest millimetre. Louvers Engineering Guide Selecting the Right louver Second consideration: Third consideration: Fourth consideration: WATER PENETRATION PRESSURE DROP WIND LOADS and STRUCTURAL ELEMENTS. Although water penetration data is The sizing of a louver for a desired pres- As a standard, all Price Louvers built published based on the AMCA Stan- sure drop and air flow rate is greatly in a single section are designed to sup- dard 500 test method, its primary use simplified with the unique Price port a 25 psf (100 mph) wind load.

6 Is for comparison purposes between NOMOGRAPHS: refer to the appro- All Louvers having 2 sections in width models and suppliers and of limited priate sheet and How to use Price by 2 sections in height or more may use in the design process since wind NOMOGRAPHS for details (see page require additional structure to support driven rain is not included. AA-11).They also permit quick selection the wind load. No accurate method exists at this time based on free area and airflow rate Louvers greater than 72 in width by 2. to design and select an intake louver or louver dimensions and free area sections in height or more may require based on water penetration.

7 Velocity or any other combination of additional structure to support the parameters as a starting point. Price wind load. Experience has shown that selecting NOMOGRAPHS have been prepared an intake louver with a reasonable for fixed blade and adjustable blade Splice angles used to join sections in margin of safety below the Beginning Louvers and penthouses. height are for alignment purposes only Point of water penetration (as defined and cannot be considered structural by the AMCA Standard 500L) will avoid When installing a damper behind a elements.

8 Significant water penetration under fixed louver , the total pressure drop can be unpredictable. Use a louver with Since louver blades are welded to the severe storm conditions. jambs, securing a louver section by an integrated damper ( combination Water penetration is not considered louver ) which is built as a single unit, its jambs and central blade support, on exhaust Louvers ; the selection is the performance is tested and predict- (if used) is considered acceptable usually based on the permissible pres- able. practice.

9 Sure drop. The pressure drop curves of Louvers It must be recognized that all Louvers are based on free area velocity and (intake and exhaust) will permit vary very little, depending almost exclu- some degree of water penetration sively on the shape of the air passage when exposed to wind driven rain. between the blades. Floor drains should be provided in the Screens can add a pressure drop plenum behind the louver . increase of up to 10%. A new test method that includes wind Fine mesh screens (insect screens). driven rain was being released by should always be made easily remov- AMCA in 1999 (AMCA Standard 500L- able and installed only during critical 1999).

10 Must be cleaned regularly At this time, no test data exists on snow to remove dirt and debris. penetration through Louvers . General Selection Guidelines Note for Louvers in multiple sections: Louvers built in multiple sections are designed with provisions for thermal expansion and when installed, should never be butted together. When the temperature varies between -35 C to 40 C, the thermal expansion of a 10 ft [3m] aluminium Engineering Guide - Louvers . louver is almost [6mm] (steel Louvers expand half this amount).