The noise caused by an industrial plant (or by a part of an industrial plant) and perceived in a surrounding residential area is not easily measurable, since it cannot be easily separable from the other sources (e.g., other plants, traffic, etc.) due to the distance between the plant itself and the residential area.
However, this kind of noise is determined by a series of industrial machineries and equipment, such as: rotating electrical machines, transformers, rotors and stators, combustion engines, compressors, electrical switch gears, ventilation fans, vibrating panels, HVAC systems, office machines, turbines, hydraulic and pneumatic tools and pumps.
When monitoring industrial noise, the operations performed by the plant equipment must be taken into account as well, since they generate different noise levels. The most typical operations depend on the kind of plant. Amongst them (and in addition to the ones enlisted above) we can mention: presses, forges, sand-blasters, furnaces, boilers, metal cutters/formers/dividers, punchers, shearers, milling machines, grinders, textile machines, printing machines, filling machines, robotic arms, conveying belts and lanes.
It is worth to say that industrial noise is a primary concern for professional workers, who have to work close to industrial equipment for a significant number of hours per day, but its effects impact also on the surrounding residential areas, especially when they are in close proximity to a plant.
As a reference, we can consider the following LEQ average values at 5m from the observer, if not specified differently, depending on the different industrial sectors (source: Health and Safety Executive, Topic Inspection Pack – Noise, HSE, May 2008):
- Size reduction machines (e.g., granulators, shredders, crumbers, etc.): 90 dB(A)
- Injection moulding machines: 95-100 dB(A)
- Extruders: 90 dB(A)
- Mould cleaning guns: 105 dB(A)
- Extrusion line cut off saws: 100 dB(A)
- Ultrasonic welding machines 95 dB(A)
- Circular saws: 95-105 dB(A)
- Moulders: 95-100 dB(A)
- Band resaws: 95-105 dB(A)
- Planer thicknessers: 97-101 dB(A)
- Mould filling / demoulding / stacking on steel tables: 95-110 dB(A)
- Mould filling / demoulding / stacking on tables with rubber coverings: 86-93 dB(A)
- Vibratory presses: 70-110 dB(A)
- Rumblers / tumblers: 85-95 dB(A)
- Extrusion plants / pallet conveyors: 86-93 dB(A)
- Cleaning equipment: up to 120 dB(A)
FOOD AND DRINK
- Glass bottling: 85-100 dB(A)
- Wrapping / bagging: 85-95 dB(A)
- Bowl choppers: >90 dB(A)
- Milling operations: 85-100 dB(A)