Acoustic Enclosures or Canopies
For diesel or gas powered generator sets.
Our enclosures or canopies are designed to suit the customer's exact requirements.
The basic concept requires answers to the following questions before we are able to offer a quotation and a design:
1. What generator set or plant is being placed inside the housing?
2. What size is the enclosed plant, what cooling airflow, what available pressure, what exhaust gas flow?
3. What site restrictions exist, if any? Height, width, length, obstructions?
4. Will the housing be externally located and subject to weather or internal and therefore protected from weather conditions?
5. What is the housing to be located on? Steel framework, concrete base, etc? Is a separate bunded base required?
6. Is the housing to be a one-piece dropover type, demountable, etc?
7. What noise limits are there, if any? How many dBA and at what distance?
8. Can the exhaust gases discharge at low level or must they be piped away to high level of other?
9. How is the housing to be finished? Painted? What specification, if this is important?
10. Where, approximately, is the site, for transportation considerations?
11. Do you require dampers (motorised, gravity, fire) to be fitted, lighting and electrics, fuel lines, etc?
Acoustic canopies are principally of the drop over design, although a fully de-mountable option is available for applications where installation space is limited. The dropover design has the advantage of low installation time, quick access to the generator set for major maintenance, integral weatherproofing and it may be re-used at alternative sites.
A further option using an acoustically treated ISO container is available. This offers the advantages of easier handling for transport and off-loading with no extra packaging being required.
The following diagram shows typical styles.
TYPICAL DESIGN STYLES OF ACOUSTIC CANOPIES
Acoustic performance is designed to match individual customer requirements and is usually based upon the proximity of the generating set to noise sensitive areas such as residential properties, offices etc. We have a comprehensive library of engine manufacturers' noise level data, together with engine exhaust gas and radiator/fan cooling air details. From this we are able to quickly determine the most economic system to meet the noise level specified.
Engines ranging from 10 - 1000 KVA output can emit from 90 up to 110 dBA at 1m distance.
Engines ranging from 1000 - 2500 KVA output can emit from 110 up to 125 dBA at 1m distance.
Noise levels decay with increasing distance and the chart shows the reductions that can be expected. The end customer will either expect you to suggest a suitable noise level, dependent on the actual site conditions, how close the neighbours are (who have every legal right to sue the operator for nuisance if they choose) and the best orientation to direct hot air and exhaust fumes away from sensitive areas - or will set his own limits required.
As a guide, where business or residential neighbours are likely to be affected by noise from the generator set, a local authority would suggest a limit of 45dBA at the boundary of the property for daytime - or 35dBA for night time operation. Where precise noise limits are set, the equipment must be designed correctly. We will be pleased to assist with individual requirements.
An acoustic enclosure can reduce this noise by varying degrees according to requirements, this meaning that the thicker and heavier the walls, in conjunction with the longer that the cooling air attenuators are, the better the acoustic performance is. There is no easy selection method for this and we have to look at each individual application to assess what is needed. Typical noise limits range from 85dBA at one metre down to 55dBA at one metre. However, the lower the noise level required, the more expensive is the solution.
The cooling air requirements for each generator set must be determined before accurate sizing can take place. This mostly involves obtaining information from the radiator manufacturer, where they should be able to advise airflow volume and additional fan pressure (i,e, pressure available over and above the requirements of the radiator alone), with regard to the operating ambient temperatures. This additional pressure is what enables the radiator fan to overcome the resistance caused by the attenuation equipment, dampers, weatherlouvres, mesh guards, etc.
The selection of attenuation must be designed correctly to avoid any possibility of overheating.
We offer a standard range of acoustic enclosures that are constructed using our 'pentapost' 75mm thick acoustic panels, fixed onto a 2.5mm thick, zinc coated steel framework. The panels have a 1.5mm thick zinc coated steel outer skin, with the acoustic infill retained in place behind 0.7mm thick, perforated galvanised sheet steel. The complete assembly has an external grey etch primer paint finish, suitable for an additional paint treatment, if required. The 60kg/m3 heavy density rock fibre acoustic infill is inert, vermin proof and non-hygroscopic. It has a Class 1 spread of flame certificate to BS 476, part 6 and has a bonded glass fibre mesh scrim facing, to prevent fibre migration. The hinged acoustic doors have an outer steel skin, with an acoustic infill sandwich. They are fitted with a lockable slam fastening handle with an internal panic release button and compressible extruded neoprene seals. Where double glazed windows are fitted, these use 6mm thick safety glass panels set into an extruded neoprene outer frame.