Specifications

LWLCWH COLUMBIA BOILER COMPANY REV. 13106
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Below a pH of 5.0 the water is acidic enough to dissolve the steel boiler plates. Under these condi-
tions the steel gradually becomes thinner and thinner until its destruction. At a pH between 5 and 9.4
pitting of shell plates will occur at a rate depending on the amount of dissolved oxygen in the boiler.
Dissolved Oxygen
Dissolved oxygen is caused by the solubility of atmospheric oxygen into the supply water. Aeration of
the city water supply is frequently used to remove other noxious gasses. Efficient aeration results in
saturation of the water with oxygen.
The majority of corrosion problems are directly related to the quantity of dissolved oxygen in the boil-
er water. Elimination of the corrosive effect of dissolved oxygen can be accomplished both directly or
chemically.
Direct or mechanical removal of dissolved oxygen is done through the use of a deaerator or by heat-
ing the water to a temperature above 180°F. Heating the water can be done with a preheater or a
sparge tube installed in the return system.
Chemical deaeration is done through the introduction of specific chemicals in the boiler to react with
the oxygen. The dissolved oxygen content should be maintained at a minimum but at no time should
it exceed 0.007 mg/l.
Sulfites
Sodium sulfite is generally used for the chemical removal of dissolved oxygen within the boiler water.
To assure the rapid and complete removal of the oxygen entering the boiler feedwater system the con-
centration of sulfite in the boiler must be maintained at a minimum of 20 PPM.
(parts per million)
Solids
Solids can be broken up into two categories: suspended solids, and dissolved solids. Suspended
solids are those which can be removed by filtration, while dissolved solids are in solution with the
water. The best test for the determination of solids content of the boiler water is through a conduc-
tance test.
The conductance value of boiler water varies by the various ionized salts present. The conductance
can be used to measure the total dissolved solids in the boiler water and to serve as an accurate
means for the control of solids through the use of blowdown.
Another test which is sometimes used as a gauge of solids is to measure the chloride present in the
boiler water. The ratio of chlorides in the boiler water to that of the feed water can be used as a means
to determine the amount of blowdown required. The chloride test is unsuitable for feedwater with low
incoming concentrations and the concentrations in the feedwater must be averaged over time for
accuracy.
High boiler solids will lead to foaming, priming, surging and carry over. These problems can be over-
come by proper, daily blowdown of the boiler.