Alkalinity, Amines, Phosphates or polymers, and Sulfites are
essential to preserve the life of a low pressure boiler. Here is the
purpose of each boiler component.
Alkalinity
is used to increase the boiler water pH to above 10.5. This serves
three purposes. pH above 10.5 will decrease your overall corrosion
rates, it will keep a 3:1 ratio of total alkalinity to silica, and it
allows the polymer to react with calcium. A 3:1 ratio keeps silica from
plating in the boiler. A low pH will result in an over general corrosion
appearance on your boiler tubes.
Amines are used to increase the
condensate pH to a range of 7.8 to 8.7. When generating steam, carbonic
acid forms and as a result your steam pH is low. Amines are volatile and
when introduced into the steam header or boiler water, amines will
increase the condensate pH. A low pH will lead to excessive condensate
pipe corrosion.
Phosphates and polymers are used to react with any
calcium in the water. The polymer attaches itself to the calcium. The
polymer and calcium then is able to exit the boiler through the surface
or bottom blowdown. Phosphate reacts with the calcium and sinks the
calcium to the bottom of the boiler. When using phosphates you must
perform boiler blowdown daily to release the phosphate and calcium.
Failure to use a polymer or phosphate will result in calcium build up on
the tubes or as some call it boiler scale. This will decrease the over
boiler efficiency and will drastically increase your fuel cost.
Sulfites
are used to remove any dissolved oxygen from the water. Dissolved
oxygen enters the boiler in make up water or as air is sucked into the
system. Dissolved oxygen is extremely corrosive to your tubes and
localized pits will form, ultimately resulting in premature tube
failure. Maintain a 20 to 40 ppm residual of sulfite in your boiler
water.
Remember water expands 100,000 times when changing from a
liquid to vapor phase. A typical home water boiler 30 gallon system has
enough energy to throw a 2,000 pound car over 100 feet in the air if
catastrophically failed. Every year people die from not implementing a
basic water treatment program.
That is boiler water treatment made simple for less then 200 psi boilers.
