HARCO Product Catalog
Section 1 Engineering Data and Design
Section 8 Spark Arresting Silencers
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ATTENUATION is a term used to describe the amount of sound reduction an exhaust silencer will provide.
ATTENUATION CURVE is a curve or graph across a range of frequencies.
CFM is a measurement of exhaust gas flow that is used to properly size silencers.
BACK PRESSURE is the amount of resistance or friction to exhaust gas flow, measured in inches of mercury (Hg) or Water (H2o).
DECIBEL ( dB ) is a unit of measure of noise level in which the faintest sound humans can hear is 0 dB, and the loudest sound the human ear can tolerate is 140 dB.
FPM stands for feet per minute or velocity of exhaust gas flow.
Selection and Installation Suggestions
- Determine which design (i.e. End In - End Out or Side In - End Out) best fits your requirements.
- In most cases silencers are too heavy to connect directly to the engine manifold. Exhaust Flex Connectors will help you make the necessary connection. This allows for thermal expansion and isolates vibration between engine and exhaust system.
- Properly secure silencer using mounting brackets or suitable hangers.
- Remember that exhaust piping from silencer's output end must be allowed to freely expand.
(Thermal Growth) Steel exhaust pipe expands 0.0076 inches per foot for every 100° (F) rise in temperature. This piping must not be allowed to put stress on the Silencer!
- Approved wall or roof thimbles must be used for any exhaust piping that passes through any combustible wall or roof.
- In most applications, choose silencer size with inlet connection at least one size larger than size of engine manifold exhaust connection, NEVER reduce or restrict silencer or piping size.
- For best attenuation exhaust piping should project upwards (vertical). Use rain cap to keep moisture out.
- Gen-sets are outdoor appliances and must never be installed in living space or any occupied spaces.