feedwater. Because gas turbine-powered ships that have
Series 9000 Oils (Diesel)
In addition to the transparency and BS&W tests, you
in all tanks (including the tank on makeup) is termed
will need to perform two other tests on 9000 series oils
reserve feedwater. The water flowing to the condensate
(diesel), the oil acidity test and the fuel dilution and oil
system is referred to as makeup feedwater.
thickening test. In performing tests on 9000 series oil
Deaerated feedwaterDeaerated feed water is
samples, follow the steps we described for each of these
produced from the condensate that flows from the
tests in the preceding paragraphs.
condenser to the deaerating feed tank (DFT) where
dissolved oxygen and other gases are removed. The
resulting deaerated feedwater then goes to the tillers.
You will sample and test water products almost as
Deaerated feedwater specifically refers to that water
frequently as you will fuel products. In sampling and
contained between the DFT and the boilers.
testing water, the primary contaminant you will deal
CondensateCondensate is the water that results
with is chloride. Chloride is the direct result of seawater
when used steam is cooled in a condenser. After the
contamination, but other contaminants are also
steam has done its work, it is coded in a condenser and
produced when seawater contamination occurs. Rust
returned to its liquid state. The condenser is a heat
formation (corrosion) and scaling can occur in boilers,
exchanger that uses seawater to cool the steam and turn
feed tanks, piping, and diesel engines. This is why you
it into water. The liquid condensed from steam is called
must frequently sample water products and provide
condensate. Water from other sources, such as makeup
feedwater and low-pressure drains, mixes with and
through a program of diligent sampling and testing.
becomes part of the condensate. The condensate goes to
a condensate cooler, and back to the feedwater tank.
treatment plan to control and eliminate the problem.
Boiler waterIf a DFT is installed, the deaerated
In the following sections, we will tell you about
feedwater, as it enters the boiler separator, becomes
various sampling locations, basic testing guidelines, and
boiler water. Boiler water specifically refers to the water
fundamental treatment procedures for water products.
in the separator, headers, and generating tubes of the
We will use different terms to refer to the water you will
sample and test at specific locations in the shipboard
water cycle. These distinctions are necessary because
Fresh waterFresh water can refer either to a
water quality standards will vary throughout the system.
ship's potable water or to water from certain steam
We will use the following terms to identify water at
drains that is returned to the condensate system.
various points in the system:
You should routinely be able to recognize and use
Distillate--The distillate is the evaporated water
these terms. Keep these terms and their definitions in
that is discharged from a ship's distilling plant. The
mind as you read the following sections.
water in a shipboard water cycle normally begins as
distillate. The distillate is stored in the feedwater tanks.
The chief engineer will designate one of these tanks as
the online feed tank and the others as reserve feed tanks.
Sampling of water products is just as important as
The distillate will be stored in the reserve feedwater
sampling of fuels and oils. The primary difference is that
tanks until it is needed as makeup feedwater.
water products will rarely show any visible signs of
Feedwater--Very simply, feedwater is the water
samples primarily for chemical testing.
(distillate) stored in the feedwater tanks. In its broad
sense, feedwater refers to all waters of the feed system,
You will draw water samples from various locations
including the reserve feedwater, makeup feedwater,
in the plant. These locations will differ according to
condensate, and deaerated feedwater systems. In its
whether the system you are testing is operating under
narrow definition, feedwater can include different types,
normal conditions or casualty conditions. In the
depending on the location of the feedwater in the system.
following paragraphs, we will discuss when you must
take samples under normal operating conditions and the
Reserve and makeup feedwaterThe distillate
sampling locations you should use.
while stored in the feedwater tanks is called reserve