Dual Chamber Silencers
Dual chamber silencers are proven, high noise reduction, low back pressure systems designed for marine engines of all sizes and proven in use over 20 years.  Every unit is Lloyds Type Approved and will last indefinitely.  A range of standard sizes is manufactured, or alternatively the body can be specifically shaped and the inlet and outlet positions varied.  Dual chamber silencers range in diameter from 400mm to 1000mm and are manufactured for exhaust systems from 90mm to 400mm. 

The graph shows the noise reduction measured by staff from the Institute of Sound and Vibration Research at Southampton University, who measured exhaust noise output on a 700hp six cylinder marine diesel with a  metre exhaust length, and then tested the same engine again when the dual chamber silencer was added to the system.  Halyard has over 25,000 Dual Chamber silencers in service on leisure and commercial craft, many of these now 20 years old.
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