Technical Information

Air Glossary

View Air Glossary of Terms

Cubic Feet Per Minute (CFM)
• CFM is measured in more than one way to apply to specific situations.

CFM variations:

Actual Cubic Feet Per Minute (ACFM)
• ACFM, when applied to compressor capacity, is the amount of air delivered, measured at prevailing
ambient inlet conditions.

Inlet Cubic Feet Per Minute (ICFM)
• ICFM is the same as ACFM for displacement type compressors but may be higher for multi-stage
centrifugal compressors, where clearance type seals may allow leakage between stages, so that the inlet
CFM may be greater than the delivered CFM.

Standard Cubic Feet Per Minute (SCFM)
• SCFM is measured at “Standard” conditions. Standard conditions refer here to the ISO Standard which
generates its measurements at these following conditions: 68° F, 0% relative humidity, and 14.5 psia.
• SCFM is the standard measure used for flow meters.

Capacity, Actual
• The quantity of gas actually compressed and delivered to the discharge of a compressor running at full-rated speed and rated pressure conditions. Actual capacity is expressed in cubic feet per minute (CFM) at the conditions prevailing at the inlet to the first stage.

Displacement
• Displacement of a compressor is the piston volume swept out per unit time; it is usually expressed in
cubic feet per minute.

Free Air
• Air at atmospheric conditions at any specific location. Because the altitude, barometer, and temperature may vary at different localities and at different times, it follows that this term does not mean air under identical or standard conditions.

Piston Displacement
• Net volume actually displaced by the compressor piston at rated machine speed is generally expressed in cubic feet per minute (usually CFM). For multi-stage compressors, the piston displacement of the first stage only is commonly stated as that of the entire machine.

Receivers
• Tanks used for storage of air discharged from compressors. They also serve to damp discharge line pulsation.

The Rule of “7”
• Some air tool manufacturers use CFM to rate their tools. This must be converted to SCFM for the purpose of properly choosing the horsepower of a compressor.
• Use 7 as an estimated (not exact) conversion factor when converting SCFM to CFM and vice versa.
• CFM to SCFM: CFM x 7 = SCFM
• SCFM to CFM: SCFM / 7 = CFM

Air Pressure Conversion

View Air Pressure Conversions: PSI, kPa, Bar

Miscellaneous Conversion Factors

PSI kPa* Bar**
85 586 5.9
90 620 6.2
95 655 6.6
100 690 6.9
125 860 8.6

(*) Preferred: Approximate to the nearest 5 kPa.
(**) Approximate to the nearest 0.5 Bar.

Hex Socket Conversion

View Socket Conversions: mm to inches
mm inches
6 mm .236”
7 mm .276”
8 mm .315”
9 mm .354”
10 mm .394”
11 mm .433”
12 mm .472”
13 mm .512”
14 mm .551”
15 mm .591”
16 mm .630”
17 mm .669”
18 mm .709”
19 mm .748”
20 mm .787”
21 mm .827”
22 mm .866”
23 mm .906”
24 mm .945”
25 mm .984”

Torque Conversion Factors

View General Torque Conversion Factors
To Convert Into Multiply By
Inch Pounds
Inch Pounds
Inch Pounds
Inch Pounds
Foot Pounds
Newton meters
Kg-meters
Kg-Cm
0.0835
0.1130
0.0115
1.1519
Foot Pounds
Foot Pounds
Foot Pounds
Foot Pounds
Inch Pounds
Newton meters
Kg-meters
Kg-Cm
12.0000
1.3560
0.1382
13.8240
Newton meters
Newton meters
Newton meters
Newton meters
Inch Pounds
Foot Pounds
Kg-meters
Kg-Cm
8.8440
0.7370
0.1020
10.2000
Kg-meters
Kg-meters
Kg-meters
Inch Pounds
Foot Pounds
Newton meters
86.8100
7.2340
9.8040
Kg-Cm
Kg-Cm
Kg-Cm
Inch Pounds
Foot Pounds
Newton meters
0.8681
0.0723
0.0980
View Torque Conversions: Ft. Lbs. to Nm
Ft. Lbs. Nm
20 27.12
50 67.79
60 81.35
100 135.58
150 203.37
200 271.16
250 338.95
300 406.75
350 474.54
400 542.33
450 610.12
500 677.91
550 745.70
600 813.49
750 1016.86
800 1084.65
1000 1355.82
View Torque Conversions: In. Lbs. to Nm
In. Lbs. Nm
2 0.23
5 0.56
10 1.13
15 1.69
20 2.26
25 2.82
60 6.78
100 11.3

Miscellaneous Conversion Factors

View Conversion Factors
To Convert Into Multiply By
Inches
Millimeters
Pounds
Kilograms
psi
bar
Millimeters
Inches
Kilograms
Pounds
bar
psi
25.4000
0.0394
0.4536
2.2050
0.069
14.5
0

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