PH is a measure of hydrogen ion concentration in a solution on a logarithmic scale. It is used to monitor the acidity or alkalinity of boiler water, with ideal ranges of 7.5-14 for boiler water and 6.5-10 for condensate water. Various tests and treatments are used to control boiler and feedwater chemistry. These include filtration to remove impurities, chemical precipitation to reduce dissolved minerals, ion exchange to remove ions, deaeration to remove oxygen, and internal treatments and blowdown to control solids concentration in the boiler.

1. 1. Define pH and how it is measured and controlled.
PH Test
Solutions of which water forms a part, contain hydrogen ions and
hydroxyl ions, when this are presentin equal amounts the solution is
said to neutral. When there is an excess of hydrogen ions it is acid,
and when an excess of hydroxyl ions it is alkaline. Keeping the water
in slightly alkaline conditionreduces corrosion.The level of acidity or
alkalinity is usually express in terms of pH Value. This is basically a
measure of the hydrogen ion concentration in the solution; for
convenience the very small values involved are express in terms of
the logarithms of their reciprocals.
PH = Logarithm of the reciprocal of the Hydrogen Ion in the solution
It should be noted that as the reciprocalis being use, the pH value
increases as the actual hydrogen ion concentration decreases.
PH Value (Reciprocalor HydrogenIon) Test
7.5 – 14.0 for Boiler Water
6.5 – 10.0 for Condensate Water
Purpose:
1. To give warning on acidity or alkalinity of boiler water sample.
2. Result help to establish the dosage of boiler compound to fight
against corrosion.
Procedures:
1.Take a 50 ml sample of the water to be tested in the plastic sample
container provided.
2.Using the white 0.6 gram. Scoop provided,add one measure of the
pH reagent to the water sample, allow dissolving – stirring if required.
3.Selectthe correctrange of pH test strip and dip it into the water
sample for one minute.
4.Withdraw the strip from the sample and compare the colorobtained
with the colorscale on the pH indicator strips container.
5.Record the pH value obtained on the log sheet provided,against
the date on which the test was taken.

2. 2.Evaluate the test used in the control up Boiler and
Feedwater Treatment.
a. Removing impurities fromboiler feedwater
Feedwater is filtered to remove suspended matter and if the
suspended solids are very fine, a flocculation step may be needed to
enable effective filtration. The water is then subjected to other treatments
to make it suitable for the boiler.
b. Filtration
Filtration is the essential first step before the chemical treatment and
conditioning of the boiler feedwater. Filtration removes or minimizes all
types of suspended solid impurities. If rust, sand (silica) etc. are not
filtered out, they lead to severe scale formation, which is difficult to clean
and reduce boiler efficiency. Even the condensate feedwater must be
filtered before returning to the boiler.
c. Coagulation and flocculation
The suspended particles in water are so fine that even cartridge
filters are unable to remove them. In such a situation, before cartridge
filtration, the water is first treated with coagulants. Coagulation is charge
neutralization of finely divided and colloidal impurities in water into masses
that can be filtered.
d. Chemicalprecipitation
Chemical precipitation is a process in which chemical added reacts
with dissolved minerals in the water to produce a relatively insoluble
reaction product. Precipitation methods are used in reducing dissolved
hardness, alkalinity, and silica.
e. Reaction of lime and soda in softening process
Calcium hydroxide (hydrated lime) reacts with soluble calcium and
magnesium carbonates to form insoluble precipitates. They form a sludge
that can be removed by settling and filtration. Lime, therefore, can be used
to reduce hardness present in the bicarbonate form (temporary hardness)
as well as decrease the amount of bicarbonate alkalinity in water. Lime
reacts with magnesium sulfate and chloride and precipitates magnesium

3. hydroxide, but in this process soluble calcium sulfate and chlorides are
formed. The calcium carbonate formed by the reaction precipitates as
sludge and can be filtered out. The resulting sodium sulfate and chloride
are highly soluble and non-scale forming.
f. Ion Exchange
Minerals dissolved in water form electrically charged particles called
ions. Calcium carbonate, for example, forms a calcium ion with positive
charges (a cation) and a bicarbonate ion with negative charges (an anion).
Some synthetic and natural materials have the ability to remove mineral
ions from water in exchange for others.
g. Deaerationof water
Dissolved oxygen in water is a major cause of boiler system
corrosion. It should be removed before the water is put in the boiler.
Feedwater deaeration removes oxygen by heating the water with steam in
a deaerating heater. Part of the steam is vented, carrying with it the bulk
of the dissolved oxygen.
h. Combination of ion exchange and lime process
A common combination treatment is the hot lime-zeolite process.
This involves pretreatment of the water with lime to reduce hardness,
alkalinity, silica, and subsequent filtration and a cation exchange softening.
This combination accomplishes several functions like softening, alkalinity
and silica reduction, some oxygen reduction, and removal of suspended
matter and turbidity.
i. Reverseosmosis
Reverse osmosis overcomes the osmotic pressure with a higher
artificial pressure to reverse the process and concentrate the dissolved
solids on one side of the membrane. Operating pressures of about 300 to
900 psi are required to achieve this. Reverse osmosis reduces the dissolved
solids of the raw water, making the final affluent ready for further
treatment. This process is suitable for any type of raw water, but
sometimes the installation and operation cost may not be economical.

4. j. Internaltreatmentof boiler feedwater
Internal treatment of water inside the boiler is essential whether or
not the feedwater has been pretreated. Internal treatment compliments
external treatment and is required regardless of whether the impurities
entering the boiler with the feedwater are large or small in quantity.
k. Blowdown
Blowdown is the discharge of boiler water containing concentrated
suspended and dissolved feedwater solids. As the blowdown water is
replaced with lower solids feedwater, the boiler water is diluted The
amount of blowdown needed depends on how much feedwater impurities a
given boiler can tolerate.
l. Corrosion in steam condensate system
Corrosion in steam condensate system is caused by carbon dioxide
and oxygen carried into the system by steam. Dissolved carbon dioxide in
condensed steam forms corrosive carbonic acid. If oxygen is present with
carbon dioxide, the corrosion rate is much higher, and is likely to produce
localized pitting. Ammonia, in combination with oxygen, attacks copper
alloys.
m. Care of out-of-serviceboilers
Much of the corrosion damage to boilers and condensate equipment
results during idle periods due to corrosion caused by the exposure of wet
metal to oxygen in the air. Wet boiler lay-up method is of storing boilers
full of water. Material, such as hydrated lime or silica gel, which absorb
moisture, is placed in trays inside the boiler. The boiler is then sealed to
prevent air from entering. Periodic replacement of the drying chemical is
required during long storage periods.