Reducing the Noise Level of Portable Compressors
Most of the noise is generated by the engine, and since the engines used are standard industrial units with no particular attention paid to silencing for the compressor market, the burden is on the compressor manufacturer to apply sound reduction techniques to the canopy enclosure. The following techniques have been found useful:
• Line the canopy with sound-deadening material. The use of such materials as absorbent foam in the engine/compressor section where there could be contamination by fuel and oil leading to a fire hazard should be avoided. Double skinning could be used instead.
• Use flexible engine mounts between engine and chassis.
• Ensure the enclosure is complete. Use undertrays. Any opening doors should be well sealed. Instruments must be capable of being read from outside without opening the doors.
• The canopy should be soundly made, reinforced where necessary to prevent panel drumming and rattle.
• Extra engine exhaust silencing.
• Line the cooling air intake and exhaust passages with sound deadening material. This is an important point to observe – much noise can escape through the cooling air passages. Use silenced exhaust valves.
• Compressor intake from inside canopy.
• Mount canopy flexibly on chassis.
Some or all of these methods arc capable of reducing noise level down to the required level. See chapter on Compressor Noise Suppression for further techniques.
In countries with high ambient temperatures, the incorporation of sound insulation material may have an adverse effect on the cooling of the compressor. Some of the insulation can be omitted but only for those countries where it is permitted.