User Manual

26 Utility AirSpade Technical Applications Bulletin
ADDITIONAL CONSIDERATIONS
SIZE
Air compressors are sized by air pressure and air flow. In the
US, pressure is measured in pounds per square inch (psi). Flow
is measured in cubic feet of air per minute (cfm). Virtually all air
compressors nominally operate at approximately 90 - 100 psi while
air flow capacities vary from model to model -- from a few cfm for
small electric piston units, to hundreds of cfm for gas or diesel driven
portable screw compressors. However, by far, the most popular tow-
behind air compressors are rated 185 cfm. At larger job sites, or
where more air flow is required to run multiple air tools, 375 cfm air
compressors are often preferred.
Utility AirSpade is available with three, off the shelf Supersonic
Nozzles to match commercially available, tow-behind air compressors.
AIR PRESSURE
Utility AirSpade Supersonic Nozzles are designed to operate optimally
at 90 psi in order to produce a Mach 2 air jet. Since the vast majority
of portable air compressors deliver compressed air in the 90 to
100 psi range, these nozzles are well-matched. Keep in mind that
increasing the air pressure above 90 psi delivered to the Supersonic
Nozzle does not lead to a proportional gain in excavation capability.
Note that a lower flow (cfm) nozzle may always be used on a higher
capacity compressor, but not the reverse. Running a nozzle with a
higher flow rating than the capacity of the compressor will result in
noticeably diminished performance.
Mode l
Nozzle Flow (cfm) Recommended Min. Compressor Size (cfm)
Utility
AirSpade
4000
105 125
150 175
225 250
AIR COMPRESSOR BASICS
What’s SCFM and PSIG?
Some manufacturers list air compressor capacity in “SCFM” which is short
for “Standard Cubic Feet per Minute.” Others use the layman’s term “CFM”
for short. Both measures are identical.
Manufacturers also list air compressor output pressure in “PSIG” or
“Pounds per Square Inch Gauge.” “PSI” is also a layman’s term and the
identical measurement.