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Application - Generator Sets Acoustic Treatment

Introduction
Generator Sets in general, produce an overall noise level in the range of 100 to 115 dB(A), depending on the rating and manufacturer. The higher the rating; the higher the noise level produces by the genset.

A typical design of Acoustic treatment for genset room normally will reduce the noise level down to 75 to 85 dB(A) measured at 1 meter away from the genset house. However, the noise can be designed to achieve better if the requirement call for it.

In Malaysia, the Department of Environment (DOE) guidelines on the Acoustic Treatment is to control the noise level to 65 dB(A) during daytime and 55 dB(A) during nighttime, measured at the boundary of premises.

Control At Source
The best way to treat noise is always to do it at the source and for Generator Sets, there are three major noise sources produce by the gensets: -

i) Noise emitted by the Radiator Fan
ii) Noise emitted by the Exhaust System
iii) Noise emitted by mechanical engine itself

Acoustic Equipment for Noise Control treatment in the generator sets room mainly consists of the following: - i) Fan Discharge Silencers ii) Intake Silencers iii) Exhaust Silencers iv) Acoustic Doors Except for the door, the rest of the equipment are in static condition where there is no moving part in the inside or outside of the Acoustic Equipment.

The width and height of the silencer will depend on the airflow of the fan. Higher airflow require the size of the silencer to be bigger.

Discharge Silencers should be not be installed too close to the fan to avoid noise regenerated by the fan blades. Flexible coupling should be used between the silencers and adjoining radiator where there is a possibility of vibration transmission.

Intake Silencers
Since the generator sets required air ventilation for cooling and combustion purposes, an opening at the generator set house is required. However, this will let the noise escape out from the room. Intake Silencers, consequently is used to serve these ends.

It is highly recommended that the Intake Silencers are not to be installed with the same side with the Discharge Silencer. This is to prevent the "short circuit" of the ventilation. Intake Silencer is normally position at the high level of the room.

Exhaust system of the generator set produce the highest noise level of all the three sources. The noise level for the exhaust is typically around 110 - 115 dB(A).

When designing an exhaust system there are a number of factors that should be considered to maximize the design in terms of performance and cost. A few of the items that should be taken into consideration include: -

• Acoustic Environment into which exhaust is discharging
• Engine Rating, i.e. - exhaust flow
• allowable engine back pressure
• engine exhaust outlet noise level
• Engine Exhaust Outlet Design, i.e. single or dual outlets
• Exhaust Piping Arrangement within engine room
• Exhaust Piping Support, Anchoring, and Guiding
• Exhaust Stack Height
• Configuration of Exhaust Silencers, i.e. single or dual inlet

ISTIQ Exhaust Silencers come in standard, stock silencers for general-purpose applications and custom models to fit most OEM engines. These include: -

Model IXP - Multi-Chamber Reactive Type Attenuation - 30 dB
Model IXS - Straight Through Absorptive Type Attenuation - 20 dB
Model IXC - Supercritical or Combination Attenuation - 35 dB

The requirement of Acoustic Door to be incorporated at the generator set room is obviously to prevent the noise from transmitting through the doorways.

ISTIQ Acoustic Doors used for generator sets are all steel doors utilising the absorptive edge principle. They are used to contain the noise within noisy areas or to prevent noise transmission to sensitive areas.