Generator Exhaust Systems – What Choices Do I Have?
Consider the following factors when selecting Generator Exhaust Systems:
1. Available space.
3. Noise reduction requirement.
4. Allowable back pressure.
7. Proximity to other components or personnel.
As a general rule, an increase in silencer size will improve the silencing level. Also, an increase in noise suppression for a given silencer volume will normally increase exhaust restriction and back pressure.
A round silencer is preferable, as it has a greater tendency to contain sound rather than allowing it to escape through a flat surface. Double-wrap tubing and a double-wall surface will also help to contain sound.
Silencers providing two levels of silencing are generally available:
Industrial silencers (approximately 15 to 20 decibels of suppression).
Residential/critical silencers (approximately 20 to 30 decibels of suppression).
Commonly, the exhaust inlet and outlet are on the ends of the silencer. However, they can also be on the sides, and this often simplifies the exhaust piping installation.
Preventing Generator Exhaust System Issues
Rainwater should be prevented from getting into the exhaust outlet. A counterbalanced, flap-type rain cap is usually the best option and can be used in many varied applications. On the other hand, conical-shaped and other similar ventilating covers are seldom practical as they can cause a high pressure drop.
Consideration should be given to the aesthetics of the exhaust outlet point. Bear in mind that gas carbon deposits may accumulate on nearby structures.
It is important to incorporate a condensate trap and drain valve into the exhaust piping design. Why? Because the diesel combustion process produces water vapour. This should be located as close as is practically possible to the engine.
For multiple-engine installs, give careful thought when combining several exhausts into one. Problems may arise if Generator exhaust systems gas finds its way into a non-operating engine whilst other engines are running. Avoid the use of check valves within the exhaust pipe runs, as they have a tendency to freeze or become inoperative.
It is also important to allow for movement between the exhaust piping and the engine. This will help prevent exhaust system components from becoming stressed or damaged due to engine mount flexibility or thermal growth.
The temperature of generator exhaust systems gas leaving the engine is generally in the region of 500°C. The piping may therefore be insulated in the same manner as steam pipes to minimise the heat radiated to the room.
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