Diesel generators always come with some form of silencer to reduce the noise levels created when they are in operation. Increased silencing will result in reduced noise levels.

Things to consider when selecting a diesel generator exhaust silencer include:

• Proximity to other components or personnel

• Appearance and aesthetics

• Space availability

• Allowable back pressure

• Required noise reduction

• Cost

Generally speaking, the silencing level will improve proportionally to an increase in the size of the silencer. An increase in noise suppression for a given silencer volume will normally increase exhaust restriction and, therefore, back pressure will be increased.

Round silencers have a greater ability to contain sound than flat surfaces. A double wrap tubing and double wall surface further helps sound containment.

Two main types of silencers exist for diesel generators: industrial silencers that provide approximately 15-20 decibels of suppression, and, residential/critical silencers, which provide 20 to 30 decibels of suppression.

The exhaust inlet and outlet are normally found on the ends of the silencer although they can be on the sides, simplifying the exhaust piping installation.

Rainwater and other contaminants must be prevented from entering the exhaust outlet opening. Counterbalanced flapper type rain caps have proved successful in this application. Conical shaped covers and other common ventilating covers are rarely used because of the high pressure drop they cause.

Over time, exhaust carbon deposits (or particulates) can accumulate on nearby structures; this is why it is important to carefully plan the location of the exhaust outlet point.

A condensate trap and drain valve is incorporated within the exhaust piping design, as close as possible to the engine, so as to drain away the water vapour that forms in the natural combustion process.

Special consideration is given when manifolding or joining the exhaust runs from the engines into one common exhaust run, in multi-engine installations. A problem may arise if one or more engines are operating and the exhaust gas finds its way back into a non-operating engine. Due to their strong tendency to freeze and become inoperative, the use of check valve devices within the exhaust pipe runs should be avoided.

So that no damaging stresses will be imposed on the exhaust system components, because of engine mount flexibility or thermal growth, allowance is to be made for relative movement between the exhaust piping and the engine.

Diesel generator exhaust system pipework may be insulated, as steam pipes are, to minimise the heat radiated to the room, as the exhaust gas temperature leaving the engine is generally in the 500° C range.

This information is provided by PowerContinuity Systems free of charge. Although great care is taken in the preparation of these articles, the information is for educational purposes only.

ABOUT POWER CONTINUITY SYSTEMS

Power Continuity Systems are market leaders in power protection providing design, manufacture, installation and maintenance of complete diesel generator systems, UPS systems and uninterruptible power supplies.

Head Office

PowerContinuity Systems

81 Spinney Hill

Melbourne

DE73 8LX

0845 055 8455