Cabinet/003 Cabinet OA Intakes.pdf: Difference between revisions
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<span style="font-size:12.0pt"><span style="font-family:">The Seasons-4 standard for outdoor air intakes is to provide an 8” deep storm-proof (“K” blade) style louver with a drainable blade that is manufactured by Seasons-4. The louver design is tested to prevent water entrainment up to a velocity of 1,000 fpm through the net free area. The net free area is calculated only considering the spaces between the blades, rather than the overall (gross) face area of the louver box. The net free area velocity will be much higher than the gross area velocity (sometimes referred to as the approach velocity). Testing was performed in-house; this louver is not AMCA certified. If an AMCA certified louver is required, the louver must be purchased.</span></span> |
<span style="font-size:12.0pt"><span style="font-family:">The Seasons-4 standard for outdoor air intakes is to provide an 8” deep storm-proof (“K” blade) style louver with a drainable blade that is manufactured by Seasons-4. The louver design is tested to prevent water entrainment up to a velocity of 1,000 fpm through the net free area. The net free area is calculated only considering the spaces between the blades, rather than the overall (gross) face area of the louver box. The net free area velocity will be much higher than the gross area velocity (sometimes referred to as the approach velocity). Testing was performed in-house; this louver is not AMCA certified. If an AMCA certified louver is required, the louver must be purchased.</span></span> |
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<span style="font-size:12.0pt"><span style="font-family:">The recommended sizing practice is to size the louver for no more than 900 fpm free area velocity, with an absolute maximum of 1,000 fpm free area velocity. Louvers should be sized for a lower free area velocity when possible, based on the overall size and space constraints of the unit. To determine the required overall size for the intake louver, the louver calculation program (</span></span> |
<span style="font-size:12.0pt"><span style="font-family:">The recommended sizing practice is to size the louver for no more than 900 fpm free area velocity, with an absolute maximum of 1,000 fpm free area velocity. Louvers should be sized for a lower free area velocity when possible, based on the overall size and space constraints of the unit. To determine the required overall size for the intake louver, the louver calculation program (</span></span><span style="font-size:12.0pt"><span style="font-family:">G:\Louver.exe</span></span>]<span style="font-size:12.0pt"><span style="font-family:">) shall be used. This program can also be accessed from the Tools menu in the Layout program. Louvers shall have a ½” x ½” birdscreen installed on the rear (air leaving) side.</span></span> |
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<span style="font-size:12.0pt"><span style="font-family:">For make-up air units (100% OA), outdoor air intake hoods shall be added in addition to the intake louvers. OA intake hoods shall be sized for a maximum velocity of 500 fpm through the free area per ASHRAE standard 62.1. Once again, louver and hoods should be sized for a lower free area velocity when possible, based on the overall size and space constraints of the unit. Where intake hoods are provided, ½” x ½” birdscreen shall be installed at the hood inlet. Please note that OA louver may have to be upsized to meet the maximum velocity requirements of the OA hoods.</span></span> |
<span style="font-size:12.0pt"><span style="font-family:">For make-up air units (100% OA), outdoor air intake hoods shall be added in addition to the intake louvers. OA intake hoods shall be sized for a maximum velocity of 500 fpm through the free area per ASHRAE standard 62.1. Once again, louver and hoods should be sized for a lower free area velocity when possible, based on the overall size and space constraints of the unit. Where intake hoods are provided, ½” x ½” birdscreen shall be installed at the hood inlet. Please note that OA louver may have to be upsized to meet the maximum velocity requirements of the OA hoods.</span></span> |
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Latest revision as of 15:36, 1 February 2021
Return to Procedures Main Menu
Index: Cabinet
Subject: (3) OA Intake Sizing
Date: January 13, 1999
Revised June 17, 2015
The Seasons-4 standard for outdoor air intakes is to provide an 8” deep storm-proof (“K” blade) style louver with a drainable blade that is manufactured by Seasons-4. The louver design is tested to prevent water entrainment up to a velocity of 1,000 fpm through the net free area. The net free area is calculated only considering the spaces between the blades, rather than the overall (gross) face area of the louver box. The net free area velocity will be much higher than the gross area velocity (sometimes referred to as the approach velocity). Testing was performed in-house; this louver is not AMCA certified. If an AMCA certified louver is required, the louver must be purchased.
The recommended sizing practice is to size the louver for no more than 900 fpm free area velocity, with an absolute maximum of 1,000 fpm free area velocity. Louvers should be sized for a lower free area velocity when possible, based on the overall size and space constraints of the unit. To determine the required overall size for the intake louver, the louver calculation program (G:\Louver.exe]) shall be used. This program can also be accessed from the Tools menu in the Layout program. Louvers shall have a ½” x ½” birdscreen installed on the rear (air leaving) side.
For make-up air units (100% OA), outdoor air intake hoods shall be added in addition to the intake louvers. OA intake hoods shall be sized for a maximum velocity of 500 fpm through the free area per ASHRAE standard 62.1. Once again, louver and hoods should be sized for a lower free area velocity when possible, based on the overall size and space constraints of the unit. Where intake hoods are provided, ½” x ½” birdscreen shall be installed at the hood inlet. Please note that OA louver may have to be upsized to meet the maximum velocity requirements of the OA hoods.
If outdoor air dampers are close coupled to OA intake louver, the damper must be sized to match the louver so that the full opening of the louver is utilized. When possible, outdoor air dampers mounted in the sidewall of Standard Supermarket units shall be sized at standards widths of 18”, 24”, 30” or 36”. The height of the damper will vary depending on the outdoor airflow requirements and internal space available in the unit.
