Manufacturing Facility 4604 Kolb Avenue Columbus, GA 31904 Tel: (800) 323-0571 Tel: (706) 323-0500 Fax: (706)
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Sales Office P.O. Box 2026 Kalamazoo, MI 49003 Tel: (706) 332-3787 Fax: (706) 323-0510
Email: info@aeriscorporation.com
Technical Bulletin
March 1, 2004 TB-001
Subject:
Air Receiver Volume Calculations For Short Term Demands
The following equation enables one to calculate the air receiver volume in terms of gallons necessary to power an air caster system for a specified length of time, given an undersized compressor:
V = T(C-S)P0 (P 1-P2)
Where: V T C S P0 P1 P2 is the receiver capacity in cubic feet is time in minutes is the air requirement of the air casters (scfm) is the air being delivered to the receiver from a compressor (scfm) is the atmospheric pressure, psia (refer to table 1 below) is the initial receiver pressure, psig is the final receiver pressure, psig
Table 1
Altitude above sea level, ft 0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500 5,000 5,500 6,000 6,500 7,000 Atmospheric pressure psia 14.69 14.42 14.16 13.91 13.66 13.41 13.16 12.92 12.68 12.45 12.22 11.99 11.77 11.55 11.33 Altitude above sea level, ft 7,500 8,000 8,500 9,000 9,500 10,000 10,500 11,000 11,500 12,000 12,500 13,000 13,500 14,000 14,500 Atmospheric pressure psia 11.12 10.91 10.70 10.50 10.30 10.10 9.90 9.71 9.52 9.34 9.15 8.97 8.80 8.62 8.45
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Air Receiver Volume Calculations For Short Term Demands (Continued)
Example: A customer currently owns a 15 HP Rotary Screw Air Compressor capable of delivering 56 scfm @ 125 psig. The load to be moved is at 1000 feet above sea level and weighs 10,000 pounds with equal loading on all casters. Aeris recommends using a 4LD21SL (rated at 32,000 pounds, 125 scfm @ 32 psig) with a 50 foot supply hose. What receiver tank size is required to provide continuous operation for 2.0 minutes. V T C S P0 P1 P2 is the tank (cubic feet) is the time (2.0 minutes) is the air requirements of the 4LD21SL on a smooth sealed concrete surface (125 scfm) is the compressor air delivery (56 scfm) is the pressure at 1000 feet above sea level (14.16 psia) is the rated pressure of the compressor (125 psig) is the final pressure. The air casters will operate at 10 psig This is calculated based upon the ratio of the actual load to the system capacity times the pressure at system capacity or (10,000/32,000) * 32 = 10 psig At this point we want to add in the pressure drop from the tank to the air casters and a safety factor to guarantee a continuous supply of air. Therefore add an additional 25 psig to the 10 psig = 35 psig.
V = 2.0 min x (125 scfm 56 scfm) x 14.16 psia (125 psig 35 psig) V = 21.7 ft3 or 162.4 gallons
Solution: Supply a ASME 200 gallon Air Receiver Tank (21.7 ft3 * 7.48052 = 162.4 gallons)1 . List price of this vertically mounted tank is approximately $773.00. Prices are subject to change without notice. Check with factory for current pricing. Dimensions: 30 inch diameter x 72 inch long. Typically equipment is moved at a safe pace of 40 feet per minute. Therefore this arrangement will allow for an 80 foot move prior to recharging the tank .
To convert cubic feet to gallons (US liquid) multiply by 7.48052. www.aeriscorporation.com
Air Receiver Volume Calculations For Short Term Demands (Continued)
In applications where it is desired to charge an air receiver tank and then discharge only the tank (ie the compressor does not operate during the discharge cycle) then in the equation found on page 1 set S = 0. Using Air Receiver Tanks to supplement existing plant air systems is a viable method of allowing air casters to be used on an intermittent basis. Its low cost and Aeris can deliver these systems in less than 4 weeks and installation is easy. If you have any questions or comments concerning the above please contact us:
Aeris Corporation 4604 Kolb Ave. Columbus, GA 31904 Email: Web: Toll Free: Phone: Fax: info@aeriscorporation.com www.aeriscorporation.com (800)323-0571 (706) 332-3787 (706) 323-0510
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