Call Us 404-363-6000      
Pye-Barker Logo Pumps Compressors Blowers Contact Us E-mail
 
Tech Tips Index
Tech Tips 1
Tech Tips 2
Tech Tips 3
Tech Tips 4
Tech Tips 5
Tech Tips 6
 
 Departments
Pumps
Compressors
Blowers & Vacuum Pumps
Cylinders
Valves
Filters/Regulators/Lubricators
Fittings & Couplers
Compressed Air Accessories
Service & Fabrication
Miscellaneous
View All Manufacturers

Product of the Month


   
 

SCFM vs ACFM

When manufacturers list performance for blowers and compressors it is stated as "Capacity" in CFM (Cubic Feet per Minute). This refers to the volume of air at the inlet to the unit, therefore this is often referred to as Inlet CFM (ICFM) or Actual CFM (ACFM). These terms are used interchangeably and mean basically the same thing (CFM, ICFM, ACFM).

In many process applications there is a critical demand for a specific minimum flow in terms of some base or reference pressure, temperature and relative humidity. Many standards are used, the most common being the Compressed Air & Gas Institute (CAGI) and the American Society of Mechanical Engineers (ASME) standards, which are 14.7 PSIA, 68Deg. F and 36% relative humidity. When you express your "Demand" in Standard CFM (SCFM), you are saying that you want this compressor or blower to deliver this CFM even at your worst case conditions.

If you have a "DEMAND" of 500 SCFM and you pick a unit from the manufacturers literature that indicates a "CAPACITY" of 500 ACFM you will not get the amount of air that you require during times when your inlet conditions vary from the standard conditions. Corrections must be made to assure that the unit furnished will provide the proper amount of air for the process to function properly.

To convert your "DEMAND" SCFM to ACFM that you can use to select a unit from the manufacturers literature, you plug your standard conditions and the "worst case" inlet conditions (that will exist at the unit) into the formula shown below:

ACFM=SCFM x Ps-(RH s x PVs) x T a x Pb
Pb – (RHa x PVa) Ts Pa
Where:
Ps = Standard pressure (PSIA)
Pb = Atmospheric pressure - barometer (PSIA)
Pa = Actual pressure (PSIA)
RH s = Standard relative humidity
RHa = Actual relative humidity
PVs = Saturated vapor pressure of water at standard temperature (PSI)
PVa = Saturated vapor pressure of water at actual temperature (PSI)
Ts = Standard temperature (DegreesR) Note: DegreesR=DegreesF + 460
T a = Actual temperature (DegreesR)

Specifying "DEMAND" in SCFM is generally limited to process applications and those who write specifications that require SCFM should always provide the following information to the vendor with the request for quotation:

- what standard you wish to use (PSIA, temp, %RH)

- worst case inlet conditions (PSIA, temp, %RH)

SCFM is not normally used when specifying "Plant Air" applications.

 

Copyright 2009© 

All rights reserved
Site created by Eric Lunsford
 

Toll-Free Customer Service: 1-800-282-9784
Atlanta 404-363-6000
Augusta 706-798-4832
Columbus 706-568-1500
Savannah 912-238-0303

Serving Industry in Georgia since 1936

Abba, Abbeville, Acworth, Adairsville, Adel, Adrian, Ailey, Alamo, Alapaha, Albany, Allenhurst, Alma, Alpharetta, Alston, Amboy, Ambrose, Americus, Appling, Arlington, Ashburn, Athens, Athens-Clarke County, Atkinson, Atlanta, Attapulgus, Auburn, Augusta, Augusta-Richmond County, Austell, Avondale Estates, Axson, Baconton, Baden, Bainbridge, Bainbridge, Baldwin, Bannockburn, Barnesville, Barney, Barretts, Barwick, Baxley, Bemiss, Berkeley Lake, Berlin, Blackshear, Blairsville, Blakely, Bloomingdale, Blue Ridge, Bogart, Boston, Bowdon, Bowens Mill, Bowman, Braselton, Bremen, Brinson, Bristol, Bronwood, Brookfield, Brooklet, Brooks, Broxton, Brunswick, Buchanan, Buena Vista, Buford, Bushnell, Byromville, Byron, Cairo, Camilla, Canton, Carnesville, Carrollton, Cartersville, Cave Spring, Cecil, Cedartown, Centerville, Chamblee, Chatsworth, Chauncey, Chester, Chickamauga, Chula, City of Calhoun, City of Summerville, Clarkesville, Clarkston, Claxton, Clayton, Cleveland, Clyatteville, Clyo, Cobbtown, Cochran, Cogdell, Cohutta, Colesburg, College Park, Collins, Colquitt, Columbus, Commerce, Conyers, Coolidge, Cordele, Cornelia, Council, Country Club Estate, Coverdale, Covington, Cox, Crawfordville, Crescent, Culloden, Cumming, Cusseta, Cuthbert, Dacula, Dahlonega, Daisy, Dakota, Dallas, Dalton, Damascus, Danielsville, Darien, Dasher, Dawson, Dawsonville, Decatur, Denmark, Dillard, Dixie, Dock Junction, Doerun, Donalsonville, Doraville, Douglas, Douglasville, Dover Bluff, DuPont, Dublin, Dudley, Duluth, East Dublin, East Point, Eastman, Eatonton, Ebenezer, Edison, Edith, Egypt, Elberton, Eldorado, Ellabelle, Ellaville, Ellenton, Ellijay, Enigma, Euharlee, Eulonia, Everitt, Fairburn, Fairmont, Fargo, Fayetteville, Fitzgerald, Flemington, Flowery Branch, Folkston, Forest Park, Forsyth, Fort Gaines, Fort Oglethorpe, Fort Stewart, Fort Valley, Franklin, Fruitland, Funston, Gainesville, Garden City, Garfield, Geneva, Georgetown, Gibson, Glennville, Glenwood, Glory, Graham, Gray, Greensboro, Greenville, Griffin, Grooverville, Groveland, Grovetown, Gumbranch, Guyton, Hagan, Hahira, Hamilton, Hampton, Hapeville, Harding, Harding, Hardwicke, Harrietts Bluff, Hartwell, Hawkinsville, Haylon, Hazlehurst, Helena, Hepzibah, Hiawassee, Hickox, Higgston, Hinesville, Hiram, Hoboken, Hogansville, Holly Springs, Holt, Homeland, Homer, Homerville, Hopeulikit, Hortense, Howell, Inaha, Iron City, Irwinton, Irwinville, Isle of Hope-Dutch Island, Jackson, Janis, Jasper, Jefferson, Jeffersonville, Jesup, Johns Creek, Jonesboro, Keller, Kennesaw, Kinderlou, Kings Bay Base, Kingsland, Kirkland, Kite, LaFayette, LaGrange, Lake City, Lake Park, Lakeland, Lanier, Lawrenceville, Lax, Leary, Leefield, Leesburg, Lenox, Lexington, Lilburn, Lincolnton, Lithonia, Locust Grove, Loganville, Lookout Mountain, Louisville, Lovejoy, Ludowici, Lulaton, Lumber City, Lumpkin, Lyons, Macon, Madison, Manassas, Manchester, Marietta, Maxeys, Mayday, McDonough, McIntosh, McIntyre, McRae, Meigs, Meldrim, Mershon, Metter, Midway, Milan, Milledgeville, Millen, Milton, Moniac, Monroe, Montezuma, Montgomery, Monticello, Montrose, Mora, Morgan, Morrow, Morven, Moultrie, Mount Vernon, Mount Zion, Mountain Park, Mystic, Nahunta, Nankin, Nashville, Needmore, Nelson, Nevils, New Rock Hill, Newnan, Newton, Nicholls, Norcross, Norman Park, Oakwood, Ochlocknee, Ocilla, Odum, Offerman, Offerman, Oglethorpe, Omega, Osterfield, Ousley, Oxford, Palmetto, Parrott, Patterson, Peachtree City, Pearson, Pelham, Pembroke, Perry, Phillipsburg, Pine Lake, Pineora, Pineview, Pooler, Port Wentworth, Portal, Potter, Poulan, Powder Springs, Preston, Pridgen, Pulaski, Queensland, Quitman, Race Pond, Ray City, Rebecca, Register, Reidsville, Remerton, Rentz, Retreat, Riceboro, Richmond Hill, Ridgeville, Rincon, Ringgold, Riverdale, Riverside, Rochelle, Rockingham, Rockmart, Rome, Roswell, Royston, Rutledge, Saint George, Sale City, Sandersville, Sandy Springs, Sasser, Savannah, Screven, Senoia, Sessoms, Shawnee, Shellman Bluff, Sirmans, Skidaway Island, Smithville, Smyrna, Snellville, Social Circle, Soperton, South Newport, Sparks, Sparta, Springfield, St. Marys, St. Simons Island, Statenville, Statesboro, Sterling, Stillmore, Stillwell, Stilson, Stockbridge, Stockton, Stone Mountain, Sugar Hill, Sumner, Sunbury, Sunsweet, Surrency, Suwanee, Swainsboro, Sycamore, Sylvania, Sylvester, Talbotton, Tallapoosa, Tarboro, Tarver, Temple, Thalman, Thelma, Thomaston, Thomasville, Thomson, Thunderbolt, Tifton, Toccoa, Toomsboro, Townsend, Trenton, Trudie, Tucker, Twin City, Twin Lakes, Ty, Ty, Tybee Island, Tyrone, Unadilla, Union City, Unionville, Upton, Uvalda, Valdosta, Valona, Vernonburg, Vidalia, Vienna, Villa Rica, Walthourville, Warner Robins, Warrenton, Warwick, Washington, Waterloo, Watkinsville, Waverly, Waycross, Waynesboro, Waynesville, Weber, West Green, West Point, Westwood, Whigham, White Oak, Whitmarsh Island, Willacoochee, Wilmington Island, Winder, Winokur, Withers, Woodbine, Woodstock, Worth, Wray, Wrightsville, Zebulon