RDG603A13
– Issue 19
Page 43 of 97
particularly where severe angles of heel are expected. The swan neck must be
450mm above heeled water line.
4. Remember that 15% of the volume of the exhaust hose may be water. The size
of the silencer selected must be such that water draining into it will fit it by no
more than one third.
5. A siphon break must be used.
The silencer may only be used in a Water Injected marine exhaust system. The overall
design of the system, and choice of components, will have a result on the back pressure in
the exhaust which is vital to the performance and life of the engine.
Barrus recommend
that Halyard (M&I) Limited are used for the Lift Silencer, Siphon Break and other
components. Contact Halyard (M&I) Limited for further information.
The silencer must be drained before the boat is craned or transported and during the
winter.
There must be at least 450mm distance between the water injection point and the position
of the silencer to allow adequate cooling of the exhaust gases. Maximum temperature
during continuous operation of the silencer is limited to 85 degrees centigrade. Normally in
a well-designed system, the temperature of the silencer should be between 50-70 degrees
centigrade. Such operation will result in longer exhaust life.
Connections to the silencer should be made using suitable exhaust hose, which is type
approved by Lloyds and DNV. Do not use oil or grease to lubricate hoses when installing,
wetting the inside of the hoses with water will help them slip more easily over the silencer
spigots. A minimum of 2 hose clips must be used. Securely tighten all hose clamps, but be
careful not to overtighten.
The silencer should be positioned within 300mm of the centre line of the vessel, or to the
engine on which it is installed. This is particularly important on sailing vessels where a
substantial angle of heel can be encountered. On systems where the exhaust manifold is
near or below the water line. A siphon break should be used to prevent the water flow
continuing after the engine shut down.
In all installations the silencer should be at the lowest point if the entire exhaust system.
The top of the silencer should be at least below the exhaust manifold outlet for the best
performance. If a distance less than is allowed, the margin of safety for preventing reverse
flow of water toward the manifold will decrease.
