Beta Marine Beta 28 Operator's Maintenance Manual page 14

HIGH-RISE EXHAUST
In yachts, engines are mostly installed low down and
often below the water line. There are several ways to
avoid cooling water entering the engine.
Syphoning of cooling water can occur when the rubber
impellor of the sea water pump becomes worn. If our
standard injection bend is too low then we can offer a
high-rise injection bend that adds 15 cms to the height.
12 Exhaust with High Rise
25 cm
EXHAUST WITH ANTI-SYPHON VALVE
When the engine is installed with the standard injection
bend - and the water injection point is still less than 25
cms above the 'static' seawater level, then you should
either install a high rise injection bend adding 15 cms to
the height or an anti-syphon valve to resolve the problem.
Some installers will always fit an 'Anti-Syphon' valve in
yachts, regardless of the position of the injection bend -
just to be as safe as possible. When fitting an anti-syphon
13 Exhaust with Anti-syphon Valve
50 cm
If this is still not enough then you have to fit an
'antisyphon' / vacuum valve 50 cms above the 'loaded'
water line sea level.
IMPORTANT!
These valves need to be checked regularly as they have
been known to block up with salt crystals over time.
Standard exhaust system for comparison only
valve to a yacht, it must be mounted as near as possible
to the centerline so that there is no possibility that the
valve goes under the water line when the yacht heels
over.
IMPORTANT!
These valves need to be checked regularly as they have
been known to block up with salt crystals over time.
Standard exhaust system for comparison only
12