Devair DRD 400 Spécifications télécharger pdf (Page 5)

General Definitions (cont'd)

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'Compressed air' is atmospheric air that has been forced into a volume smaller than it normally occupies.

At an air pressure above that of atmospheric pressure, the compressed air will always want to return to it's normal,

uncompressed state. It is this process that enables the compressed air to do work. This is similar to a spring, wanting

to return to it’s shape at rest.

In dealing with air volume, we must have a unit of measure that is easily recognizable. The standard measure of air

volume is 'Standard Cubic Feet'. The amount of volume used in a given period of time is generally measured in

'Standard Cubic Feet per Minute', or 'SCFM' for short.

Compressed air, as a whole, is generally measured as a volume of air dispensed over a period of time (CFM), and at a

certain pressure (psi). An example: a Compressor Unit may provide 18 CFM @ 150 psi.

‘Figure 3’ shows the effect that compressing one cubic foot of air at 0 psi has when compressed to 75 psi. This figures

shows that as the pressure of air increases, the volume decreases. At 75 psi, the volume of air is roughly 1/6 of that at 0

psi.

Typically, compressing air yields the discharge of both heat and moisture. The greater the air volume compressed,

and the higher the pressure, the greater the heat generated. Moisture is simply caused by the inability of air to hold

moisture as it's pressure increases.

With proper guidance, as dealt with later in this booklet, heat and moisture need not be a concern.

'Figure 3’

Air at Atmospheric Pressure

(0 psig)

1 Standard

Cubic Foot

of Air

@ 0 psi

Air at an Elevated Pressure

(75 psig)

1 Standard

Cubic Foot

of Air

@ 75 psi

2”

In order that Air Compressors are manufactured and and tested in a uniform manner within the industry, testing and

related data and efficiencies are made at what is termed ‘Standard Air’. ‘Standard Air’ is considered to be air at a

temperature of 68°F, atmospheric pressure of 14.7 psi, and a relative humidity of 36%.

Should the ambient temperature rise above 68°F, there will be a loss of air delivery equivalent to 2% for every 10°F

increase in temperature.

What is Compressed Air ?

Are there any ‘by-products’ in compressing air?

General Information

Information Bulletin IFB-01

March ‘07

For Sales & Service contact:

CENTRAIR Air Systems & Supplies 705-722-5747 [email protected] www.centrair.ca

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Devair DRD 400 Spécifications Page 5

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