eco-ATWB Marketing - Evapco

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IBC COMPLIANCE Site Coefficient (Fa) – Values ranging from 0.8 to 2.5 determined based on the Ss and the Site Classification. Table 1613.5.3(1) in the IBC 2006 Code Book defines these values. Design Spectral Response Acceleration (SDS) – A calculated value using the values for Ss and Fa. Amplification Factor (ap) – 2.5 for flexible components or flexibly attached components. Due to its low inherent natural frequencies, most evaporative cooling equipment falls under the definition of flexible. Therefore the default for Closed Circuit Coolers is 2.5. See Table 13.6-1 in the American Society of Civil Engineers (ASCE) Standard 7-05, to which IBC often references, for more information. Response Modification Factor (Rp) – 2.5 for nonisolated evaporative cooling equipment. 2.0 for vibration isolated evaporative cooling equipment. Table 13-6.1 of ASCE 7-05 provides additional information. Component Operating Weight (Wp) – This weight term has been removed from the equation below, because EVAPCO is expressing the force in terms of g’s and not lbs. Importance Factor (Ip) – 1.5 for Occupancy Category IV, life safety components required to function after a seismic event or component containing hazardous content. 1.0 for all other components. ASCE 7-05 Section 13.1.3 provides additional detail on importance factors. Installation Location (Z/h) – 0 for units installed at ground level. 1.0 for units installed on a rooftop. Per ASCE 7-05 Section 13.3, z = the height of the point of attachment of the component and h = the relative roof height. Seismic Design Force, (Fp) – “G-force” that the unit must be able to withstand. This number is calculated using the factors described above. The New ATWB is offered with a choice of two structural design packages, consisting of: – Standard Structural Design ≤ 1.0g – Upgraded Structural Design – up to 5.12g (the maximum value for North America) Seismic Load Sample Calculation The following example demonstrates the procedure for determining which structural design package a Community Hospital located in Charleston, SC (zip code 29401) would require under the latest version of IBC. In this example, the closed circuit cooler will be installed on a roof, approximately 60 feet above grade. The unit will also be installed with a vibration isolation system. Step 1: Calculate the Design Spectral Response Acceleration (SDS) Where: SS = 1.495; using the USGS Ground Motion Parameter Calculator Fa = 1.0; from Table 1613.5.3(1) in the IBC 2006 Code Book assuming a Site Classification of D Step 2: Calculate the Seismic Design Force (Fp ) Where: ap = 2.5; the default for cooling towers and closed circuit coolers SDS = 0.9966; as calculated in Step 1 Wp = 1.0; the default for cooling towers and closed circuit coolers Rp = 2.0; the default for isolated equipment Ip = 1.5; the default for life safety components z/h = 1.0; the default for units on a rooftop In order to meet Code requirements, the unit and its anchorage must be constructed to withstand 2.24g. This will require that the upgraded structure option be chosen to meet the seismic requirements of this project. Because the seismic load requires the upgraded structural design, the wind load calculation results will not change the design and are not required for this analysis. 20
IBC COMPLIANCE Wind Load Calculations Note, both the standard construction and the upgraded construction ATWB Closed Circuit Cooler are designed to meet a wind load of 145 psf. Therefore, the following details are provided for informational purposes only. The data required to calculate the wind load are: Basic Wind Speed (V) – Numerical value, in miles per hour (mph) found in ASCE 7-05 Figures 6-1 (A,B,C). Wind Directionality Factor (Kd) – 0.85 for building components and cladding. Table 6-4 of ASCE 7-05 provides additional information. Occupancy Category – I, II, III or IV depending on the nature of the building occupancy. Table 1604.5 in the IBC 2006 Code Book defines each of the categories in detail. This is the same Occupancy Category used in Seismic calculations. Importance Factor (I) – Numerical value between 0.77 and 1.15 based on the Basic Wind Speed and the Occupancy Category. These values are found in Table 6-1 of ASCE 7-05. Exposure Category – B, C or D as defined in Section 6.5.6.3 of ASCE 7-05. Component Elevation (z) – The anchorage height of the unit in feet. Nominal Height of the Atmospheric Boundary Layer (zg) - Numerical value based on Exposure Category. These values are found in Table 6-2 of ASCE 7-05. 3 second Gust-Speed power Law Exponent (α) - Numerical value based on Exposure Category. These values are found in Table 6-2 of ASCE 7-05. Velocity Pressure Exposure Coefficient (Kz) – A calculated value using the values for zg and α. z KZ = 2.01( zg) 2 ( a ) Wind Load Sample Calculation The following example demonstrates the procedure to determine which structural design package a Condominium Building located in Miami, FL (zip code 33101) would require under the latest version of IBC. In this example, the closed circuit cooler will be installed on the top of the 60 foot tall building. Step 1: Calculate the Exposure Category Coefficient (Kz) Where: z = 60; Installation Height zg = 700; from ASCE 7-05 Table 2 using an Exposure Category of D. α = 11.5; from ASCE 7-05 Table 2 using an Exposure Category of D. Step 2: Calculate the Velocity Pressure (qz) Where: KZ = 2.01 ( a ) ( ) ( 11.5) 2 2 z 60 = ( zg) 2.01 = 700 1.31 qz = 0.00256(Kz)(Kzt)(Kd)(V 2 )(I) = 0.00256(1.31)(1.0)(0.85)(145 2 )(1.0) = 59.93psf Kz = 1.31; as calculated above. Kzt = 1.0; default when topographic effects are not a factor. Kd = 0.85; default for building components and cladding. V = 145; wind speed from ASCE 7-05 Figure 6-1. I = 1.0; Based on an Occupancy Category of II. Topographic Factor (Kzt) – 1.0 default when topographic effects are not a factor. ASCE 7-05 Section 6.5.7 provides additional detail on topographic factors. Velocity Pressure (qz) – This number in pounds per square foot (psf) is calculated using the factors described above. The New ATWB is offered with a choice of two structural design packages, consisting of: – Standard Design and Upgraded Structural Design – both up to 145 psf (the maximum value for North America) In order to meet Code requirements, the unit and its attachments must be designed and constructed to withstand 59.93 psf. Because the wind load does not dictate the closed circuit cooler design, the seismic load calculation must also be completed to determine if the results will change the unit design. 21
Page 2 and 3: NEW! Ellipti-fin Featuring Elliptic
Page 4 and 5: D ESIGN F EATURES Principles of Ope
Page 6 and 7: S P E C I F I C AT I O N S SECTION
Page 8 and 9: O P T I O N A L E Q U I P M E N T E
Page 10 and 11: The Water and Energy Conservation C
Page 12 and 13: D ESIGN F EATURES Principles of Ope
Page 14 and 15: SAGE SYSTEM EVAPCO’s … Water an
Page 16 and 17: D ESIGN F EATURES eco-ATW Operating
Page 18 and 19: IBC COMPLIANCE In its continuing co
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