Compressed Air Best Practices - March 2009 - (Page 27) Focus Industry ENERGY MANAGEMENT | 03/09 | ® 1. The effects of relative humidity (RH) on “G” for air is 0.6% over the range of 0 to 100% RH, and therefore can be ignored. This equation is valid for subsonic flow only. To insure subsonic flow (flow velocities below the speed of sound [1100 ft/sec]), limit pressure drop so that: P2 + Pa is between .85 and 1.0 P + Pa 1 2. Distribution piping should be sized so that the air velocity within the pipe does not exceed 30 ft/sec. Higher velocities may cause condensate to be blown across a condensate drop leg, and cause lager pressure excursion to occur. The following equation explains the sizing process: d a = π4 2 d= a4 π Where: a = Cross-sectional area of pipe bore, in2 d = Pipe bore diameter, in. Let’s use our 363 scfm flow from the 8-inch cylinder. a= 144 QPa Q V 60( Pd + Pa ) The following reference table is an easy resolve from the above equation: Where: a = Cross-sectional area of the pipe bore, in2 Q = Flow rate, ft3/min free air Pa = Prevailing atmospheric absolute pressure, psia Pd = Compressor discharge gauge pressure (or line pressure), psig V = Design pipe velocity, ft/sec (we will use 30) Here is the equation for sizing a pipe for the 363 scfm of air and keeping the velocity at 30 ft per second. a = V 60( Pd +aPa ) d a = π4 2 144 QP a= 144(363)(14.5) (30)60(80 +14.5) a = 4.455873in 2 or d= a4 π d= 4.455873(4) π d = 2.38in (Continued on pg. 34) Using the “A” constant for the above table, the formula becomes: Cv = Flow rate (scfm) x A Our 8-inch cylinder example with a 2 psig pressure drop would become: Cv = 363 x .075 = 27 SIZING PIPE FOR A GIVEN FLOW The more flow you try to put through a pipe the greater the pressure drop will be. Pressure drop in a pipe increases with the square of the increase in flow. Which means if you double the flow, the pressure drop will increase four times what is was! www.airbestpractices.co www.airbestpract ices.com www.airbestpractices.com t 27 7 http://www.electratherm.com http://www.electratherm.com http://www.airbestpractices.com
Table of Contents Feed for the Digital Edition of Compressed Air Best Practices - March 2009 Compressed Air Best Practices - March 2009 Contents From the Editor Utility-Air News Compressed Air Audit of the Month Air Standards Assessment Improves Electroplater Production and Saves Energy Demand-Side System Optimization Seven Sustainability Projects for Industrial Energy Savings Personal Productivity Resources for Energy Engineers Wall Street Watch Advertiser Index Classifieds Compressed Air Best Practices - March 2009 Compressed Air Best Practices - March 2009 - Compressed Air Best Practices - March 2009 (Page Cover1) Compressed Air Best Practices - March 2009 - Compressed Air Best Practices - March 2009 (Page Cover2) Compressed Air Best Practices - March 2009 - Compressed Air Best Practices - March 2009 (Page 3) Compressed Air Best Practices - March 2009 - Contents (Page 4) Compressed Air Best Practices - March 2009 - Contents (Page 5) Compressed Air Best Practices - March 2009 - From the Editor (Page 6) Compressed Air Best Practices - March 2009 - Utility-Air News (Page 7) Compressed Air Best Practices - March 2009 - Utility-Air News (Page 8) Compressed Air Best Practices - March 2009 - Utility-Air News (Page 9) Compressed Air Best Practices - March 2009 - Compressed Air Audit of the Month (Page 10) Compressed Air Best Practices - March 2009 - Compressed Air Audit of the Month (Page 11) Compressed Air Best Practices - March 2009 - Compressed Air Audit of the Month (Page 12) Compressed Air Best Practices - March 2009 - Compressed Air Audit of the Month (Page 13) Compressed Air Best Practices - March 2009 - Compressed Air Audit of the Month (Page 14) Compressed Air Best Practices - March 2009 - Compressed Air Audit of the Month (Page 15) Compressed Air Best Practices - March 2009 - Compressed Air Audit of the Month (Page 16) Compressed Air Best Practices - March 2009 - Air Standards (Page 17) Compressed Air Best Practices - March 2009 - Air Standards (Page 18) Compressed Air Best Practices - March 2009 - Air Standards (Page 19) Compressed Air Best Practices - March 2009 - Air Standards (Page 20) Compressed Air Best Practices - March 2009 - Assessment Improves Electroplater Production and Saves Energy (Page 21) Compressed Air Best Practices - March 2009 - Assessment Improves Electroplater Production and Saves Energy (Page 22) Compressed Air Best Practices - March 2009 - Assessment Improves Electroplater Production and Saves Energy (Page 23) Compressed Air Best Practices - March 2009 - Demand-Side System Optimization (Page 24) Compressed Air Best Practices - March 2009 - Demand-Side System Optimization (Page 25) Compressed Air Best Practices - March 2009 - Demand-Side System Optimization (Page 26) Compressed Air Best Practices - March 2009 - Demand-Side System Optimization (Page 27) Compressed Air Best Practices - March 2009 - Seven Sustainability Projects for Industrial Energy Savings (Page 28) Compressed Air Best Practices - March 2009 - Seven Sustainability Projects for Industrial Energy Savings (Page 29) Compressed Air Best Practices - March 2009 - Seven Sustainability Projects for Industrial Energy Savings (Page 30) Compressed Air Best Practices - March 2009 - Seven Sustainability Projects for Industrial Energy Savings (Page 31) Compressed Air Best Practices - March 2009 - Seven Sustainability Projects for Industrial Energy Savings (Page 32) Compressed Air Best Practices - March 2009 - Seven Sustainability Projects for Industrial Energy Savings (Page 33) Compressed Air Best Practices - March 2009 - Seven Sustainability Projects for Industrial Energy Savings (Page 34) Compressed Air Best Practices - March 2009 - Seven Sustainability Projects for Industrial Energy Savings (Page 35) Compressed Air Best Practices - March 2009 - Seven Sustainability Projects for Industrial Energy Savings (Page 36) Compressed Air Best Practices - March 2009 - Seven Sustainability Projects for Industrial Energy Savings (Page 37) Compressed Air Best Practices - March 2009 - Seven Sustainability Projects for Industrial Energy Savings (Page 38) Compressed Air Best Practices - March 2009 - Seven Sustainability Projects for Industrial Energy Savings (Page 39) Compressed Air Best Practices - March 2009 - Personal Productivity (Page 40) Compressed Air Best Practices - March 2009 - Personal Productivity (Page 41) Compressed Air Best Practices - March 2009 - Personal Productivity (Page 42) Compressed Air Best Practices - March 2009 - Resources for Energy Engineers (Page 43) Compressed Air Best Practices - March 2009 - Resources for Energy Engineers (Page 44) Compressed Air Best Practices - March 2009 - Resources for Energy Engineers (Page 45) Compressed Air Best Practices - March 2009 - Wall Street Watch (Page 46) Compressed Air Best Practices - March 2009 - Wall Street Watch (Page 47) Compressed Air Best Practices - March 2009 - Wall Street Watch (Page 48) Compressed Air Best Practices - March 2009 - Advertiser Index (Page 49) Compressed Air Best Practices - March 2009 - Classifieds (Page 50) Compressed Air Best Practices - March 2009 - Classifieds (Page Cover3) Compressed Air Best Practices - March 2009 - Classifieds (Page Cover4)
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