Westerbeke WPDS-20 Technical Manual page 11

10
cause rapid deterioration. Galvanized
iron fittings and galvanized iron pipe is
recommended for the exhaust line. The ex-
haust line must be at least as large as
the engine exhaust manifold flange and be
increased in size if there is an especial-
ly long run and/or many elbows. It should
be increased by 1/2" in
I.
D. for every 10
feet beyond the first 10 feet.
EXHAUST SYSTEM WITH WATER JACKETED
STANDPIPE
To insure vibration doesn't transmit to
hull, use a flexible section preferably of
stainless steel, no less than 12" overall,
threaded at each end and installed as
close to the engine as possible. This
flexible section should be installed with
no bends and covered with insulating mater-
ial. The exhaust pipe should be properly
supported by brackets to eliminate any
strain on the manifold flange studs. Many
installations use flexible rubber exhaust
hose for the water cooled section of the
exhaust line because of the ease of instal-
lation and flexibility. Provide adequate
1.3/4" 0.0.
'0'1"'0 0
0;
11-1/2"
01.0,
1"11J~"L
ER, PN 1)1;1,.
1-311.." 0,0.
5-318"
WATER LIFT EXHAUST SYSTEM WITH
"HYDRO-HUSH" MUFFLER
support for the rubber hose to prevent
sagging, bending, and formation of water
pockets.
Always arrange that water discharge
into the rubber hose section is behind a
riser or sufficiently below the exhaust
flange so that water cannot possibly flow
back into the engine. Also make sure that
entering sea water cannot spray directly
against the inside of the exhaust piping.
Otherwise excessive erosion will occur.
MEASURING EXHAUST GAS BACK PRESSURE
Back pressure must be measured on a
straight section of the exhaust line and
as near as possible to the engine exhaust
manifold. The engine should be run at
maximum load during the measurement period.
Set-up should be as shown below.
1. For normally asperated engines:
Pressure Test Mercury Test Water Column
1-1/2" Max PSI 3" Mercury
39"
2. For turbo-charged engines:
Pressure Test Mercury Test
0.75 Max PSI 1-1/2" Mercury
Checking The Back Pressure
1. Exhaust pipe flange
2. Exhaust line
Water Column
19-1/2"
3. Transparent plastic hose, partly filled
with water. Measurement "A" may not
exceed 39" for normally asperated
engines and 19.5" for turbo-charged
engines.
WATER CONNECTIONS
Seacocks and strainers should be of the
full flow type at least one size greater
than the inlet thread of the sea water
pump. The strainer should be of the type
which may be withdrawn for cleaning while
the vessel is at sea.
Water lines can be copper tubing or
wire-wound, reinforced rubber hose. In