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E. Boiler Water Treatment
Water treatment is required for satisfactory operation
of the boiler. It must be devised to prevent depositing
of scale and corrosion from acids, oxygen and other
such harmful elements that may be in the water
supply. A qualified water treatment chemist should
be consulted and the water systematically treated.
"Hot water systems must operate with a pH above 8.5.
A system that has a pH below 8.5 will usually develop
the following problems:
• Gas formation (air trouble)
• Pump seal and gland problems
• Air vents sticking and leaking
• Frequent relief valve operating
• Piping leaks at joints
(American Boiler Manufacturers Association [ABMA],
2005. Boiler Water Quality Requirements and
Associated Steam Quality for Industrial / Commercial
and Institutional Boilers)"
The basic objectives of water treatment are:
• Prevent the accumulation of scale and deposits
in the boiler.
• Remove dissolved gases from the water.
• Protect the boiler against corrosion.
• Maintain the highest possible boiler fuel
efficiency.
• Decrease the amount of boiler down time from
cleaning.
1. Water Softener
a. It is highly recommended that a zeolite water
softener be used for all make-up to the boiler.
It is intended that this be used in addition to
the chemical treatment of the boiler. Water
softening removes calcium and magnesium,
the primary causes of hard boiler scale.
Thermal Solutions, 1175 Manheim Pike, Lancaster, PA 17601 Website: www.thermalsolutions.com
Phone: 717-239-7642 Fax: 877-501-5212 Email: sales@thermalsolutions.com
2. Continuous Monitoring
a. Water treatment should be checked and
maintained according to Table 27 whenever
the boiler is operating. The boiler operator
should be sure that the boiler is not operating
for long periods without proper water
treatment.
b. Water treatment may vary from season to
season or over a period of time. Therefore,
the water treatment procedure should be
checked not less than four times a year and
possibly more frequently as the local water
conditions may indicate.
c. See Table 26 for examples of typical chemical
agents found in untreated water along with
their potential effects.
Table 26: Chemical Agents and Effects
Compound
Calcium Carbonate, (CaCO
Calcium Bicarbonate (CaHCO
Calcium Sulphate (CaSO
4
Calcium Chloride (CaCl
2
Magnesium Carbonate (MgCO
Magnesium Bicarbonate (MgH-
CO
)
4
Magnesium Sulphate (MgSO
Silicon Dioxide (SiO
)
2
d. It should be noted that water boilers may well
need chemical treatment for the first filling
plus additional periodic chemical treatment,
depending on system water losses and the
makeup requirements.
e. All water introduced into the boiler should
be softened and should include an oxygen
scavenger like sodium sulfite. This is required
to remove dissolved oxygen from the water.
Dissolved oxygen will cause severe system
corrosion.
Effect
)
Soft Scale
3
)
Soft scale, CO
3
2
)
Hard Scale
)
Corrosion
)
Soft Scale
3
Corrosion, Scale
)
Corrosion
4
Hard Scale
43
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