Westerbeke 3.5 SBCG Operator's Manual page 10

CARBON MONOXIDE "CO" I LOW-CO GENERATORS
IMPORTANT INFORMATION
Catalyst performance will degrade over time. As the
generator accumulates operating hours, CO concentrations
will increase. The catalyst must be replaced every 2,000
hours of engine operation.
Verification of satisfactory CO levels must be done
seasonally or each 500 hours (which ever occurs first).
Verification involves actual sampling of exhaust gas with an
appropriate CO analyzer.
There are two locations where exhaust gas can be sampled.
Dry,
but hot, exhaust gas can be sampled at the 118NPf
plugged opening on the top of the water injected exhaust
elbow's casting. Measurements at this location may not be
practical in all instances due to the high exhaust temperature,
temperature limits of the analyzer, safety concerns over
temperatures involved or the possibility of high levels of CO.
The other location is the boat's exhaust outlet, which
contains entrained cooling water (except dry stack exhaust
systems). Only analyzers with probes should be used at this
location and it is critical that the probe not ingest water.
Probe-type analyzers have an air pump drawing a gas sample
through the probe. As a result, they tend to ingest water when
it is present. Be sure to aim the probe downwards with the
opening pointed in the direction of the water flow and just
out of the flow. Position the analyzer as high as possible with
the tubing leading to the probe running continuously down-
hill. Observe the usually translucent tubing between the
probe and the analyzer and be sure no water is being
ingested. If any water is ingested into the analyzer, it must be
repaired or replaced and recalibrated.
When measuring CO at the exhaust outlet be aware of the
ambient CO level by also measuring CO away from and
upwind of the exhaust outlet. especially in marinas. the CO
level at the exhaust will be influenced upwards by the
ambient level.
For changing the exhaust
catalyst
and measuring the
exhaust
back pressure,
refer to the Table of Contents.
Whenever taking the time to verify proper CO levels from the
exhaust with a CO analyzer, always take theopportunity to
use the analyzer to "sniff' around the engine looking for CO
from exhaust leaks. Pay close attention to the connection of
the cylinder block to the sump plate, the sump plated to the
water injected exhaust elbow casting and all subsequent
downstream exhaust components and hoses and connection
points. Remember, exhaust gas that has not yet passed
through the catalyst is raw exhaust, untreated exhaust gas and
is very high in CO content.
Analyzers usually require periodic calibration. Follow the
instructions that come with the analyzer very carefully
regarding calibration.
The following are manufacturers that offer CO analyzers:
Extech, TIF, Testo, TSI, Bacharach, Fluke, Monoxor, Fyrite,
Zellwgwer Analytics, Industrial Scientific Corp, GFG, TPI,
Teledyne and others. Westerbeke recommends analyzers with
a probe connected to the analyzer by a length of transparent
tubing. They are slightly more expensive than those with the
sensor built into one end of the analyzer, but they allow you
to sample the exhaust coming out of the boat's exhaust outlet.
Engines
&
Generators
vi