Ventilation Systems: Operation and Testing - GHDonline

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Example Problem • What static pressure (S Ph ) should be set at the bench grinder hood to maintain a duct velocity of 4000 fpm if the take-off duct size is 4 inch diameter ? • What is the volumetric flow rate ? Example Problem • V = 4000 fpm Q = VA = 4005(A)(V P ) 0.5 Q = VA = 348 cfm • A for 4 inch duct diameter = 0.087 ft 2 • C e bench grinder hood = 0.78 V = 4005 (V P ) 0.5 C e = (V P /S Ph ) 0.5 = 0.78 (VP) 0.5 = (4000)/(4005) (V P /S Ph ) = (0.78) 2 V P = 0.998 in w.g. S Ph = V P /(0.78) 2 = (0.998)/(0.608) = 1.64 in w.g. 14
Air Flow Characteristics • See Industrial <strong>Ventilation</strong> Manual notes Blowing vs. Exhausting Air Flow Characteristics Exhaust Hoods Capture Velocity From Dalla Valle’s empirical work V (x ) = Q/ (10 x 2 + A) 15
Page 1 and 2: Engineering Methods for the Control
Page 3: Types of Systems • Supply Tempera
Page 6 and 7: Factors in the Perception of Air Qu
Page 8 and 9: Types of Pressure Measurements •
Page 10 and 11: Velocity Pressure & Velocity • V
Page 12 and 13: Flanged Inlet with Fd = 0.49 Flange
Page 16: Capture Velocity V (x) = Q/ (10 X 2

Ventilation Systems: Operation and Testing - GHDonline

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