Compressed Air Best Practices - January 2008 - (Page 15)

Focus Industry ENERGY MANAGEMENT | 01/08 | Estimated and Measured Performance Curves from Lubricant-Free Examples Actual input kW of the 3 units described, oilfree two-stage rotary screws, 350 hp 2-step constant speed, 350 hp variable speed (the two 350 hp units are equal at about 80% flow, from 80 to 100% the 2-step becomes more efficient, from 80% down the VSD is more efficient). Lubricated Screw VSD vs Lubricated Vane 100.00 90.00 80.00 % Full Load Average BHP 70.00 60.00 50.00 40.00 30.00 20.00 10.00 0.00 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0 % of Compressor Capacity Lubricated Rotary Screw VSD Lubricated Rotary Vane (Metal) VSD Lubricant Cooled Rotary Metal Vane Compressors Lubricant Cooled Sliding Vanes: The lubricant cooled sliding metal vane compressor is another very reliable product from 5 to 125 hp and its basic operating characteristics create a very favorable VSD performance curve. The following graph shows the typical efficiency relationship between the lubricant cooled rotary screw VSD and lubricant cooled metal sliding metal, single-stage vane VSD. From 100% to 35/40% load the vane unit is more power efficient because the peripheral pressure of the vane to the cylinder walls falls as the rpm slows reducing the friction load. This creates about 10% difference around 50–60% flow. The relative performance deterioration of the vane graph below 35% flow is the effect of the capacity control and becomes a combination of inlet valve modulation and VSD. This lower-end difference is also about a maximum of 10% over a little shorter range. Remember this is a percent (%) of full load kW and is an estimate — “attention to detail” is still needed to make the proper selection and realize the optimum benefits. BP EMERGING MARKET CONTENT DISCOVER W W W.DISCOVERCURTIS.COM ©2007 Curtis-Toledo, Inc. www.airbestpractices.com 19282b CTGNL GENRL Emerging.indd1 1 9/4/07 15 4:18:25 PM http://WWW.DISCOVERCURTIS.COM http://WWW.DISCOVERCURTIS.COM http://www.airbestpractices.com

Table of Contents Feed for the Digital Edition of Compressed Air Best Practices - January 2008

Compressed Air Best Practices - January 2008 Contents Focus Industry Features Compressed Air Industry Articles From the Editor Real World Best Practices: Selecting A VSD Rotary Compressor Audit of the Month: Energy Savings in Peru The Low-Hanging Fruit in Pneumatic Systems Mikropor America, Inc. Wireless Sensor Networks: Improve Efficiency in Compressed Air Systems Special Report: The Chicago Pneumatic Compressor Launch in North America The Importance of Measuring Vacuum The Comp-Air Service Co. Special Report: The 2007 NAACD Wall Street Watch Advertiser Index Job Market

Compressed Air Best Practices - January 2008

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