An instrument designed to detect the ultrasonic emissions and
convert them to audible signal.
UNC
Thread - Unified national coarse.
UNF
Thread - Unified national fine.
Unit type
compressors
Compressors of 20 HP or less, generally combined with all the
components required to put the into operation.
Unload
The air compressor continues to run, usually at full RPM, but
no air is delivered because the inlet is either closed off or
modified, not allowing inlet air to be trapped.
Unloaded horsepower
The power that is consumed to overcome the frictional losses
when operating in an unloaded condition.
Utilization factor
The ratio in percentage of the time that the equipment is in
operation to the total working time.
