How noisy is a medical air plant?

HTM 02-01 asks for plantrooms designed and constructed to ensure satisfactory control of noise emission, with their construction also considering noise attenuation and the reduction of vibration transfer. Compressor noise values should be assessed as part of the main project design and, where necessary, a competent acoustician should advise on compliance with environmental and operational noise criteria. Free-field noise levels should be provided to support the acoustic design of the plantroom.

Running several machines together adds up: in duplex and multiplex installations, HTM 02-01 says the free-field noise level outside the plantroom increases by 5 dBA for each additional pump or compressor operating, over and above the specified limits.

Noise control measures in HTM 02-01

• Acoustic enclosures to reduce free-field noise in noise-sensitive areas next to the plantroom, designed so that they do not inhibit normal cooling or maintenance.
• Acoustic treatment of the plantroom, such as acoustic lining, which HTM 02-01 says may be preferable to individual acoustic cabinets: where cabinets are removable, their noise attenuation may be lost.
• Anti-vibration mountings under compressors and pumps, where necessary, to minimise the transfer of noise and vibration to the building structure.
• Flexible connectors on pipework and electrical conduits, where necessary, to prevent noise and vibration travelling along them.
• Silencing for the exhausts of electronic drains and purge valves, whose pitch and volume may cause a nuisance, and additional screens, filters and silencers on the compressor air intake where required.

Noise figures in the Ultra Controlo tables

The ULTRAAR ESW medical air plant uses oil-less ULTRACECO ESW piston compressors. The ULTRACECO ESW datasheet gives noise measured at 1 m according to Pneurop/CAGI PN8NTC2: 82 to 95 dB(A) for the models without CA in their name and 67 to 70 dB(A) for the models marked CA. These are compressor values at 1 m, not the level of a complete plant or the level outside a plantroom.