Sussman ES Installation, Operation And Maintenance Manual - page 23
For optimum results, the feedwater supply should be tested prior to initial start-up. If the
mineral content exceeds the following recommended limits, various external treatment
processes (water softener, reverse osmosis, etc.) may be used to correct the problem.
NOTE: An analysis of the on-site boiler feedwater must be made by a
recognized and reliable water treatment company to ascertain the existing
condition and treatment required.
RECOMMENDED FEEDWATER QUALITY
HARDNESS, ppm
8 – 85 (~0.5 – 5 gpg)
P-ALKALINITY, ppm
85 – 410 (~5 – 24 gpg)
T-ALKALINITY, ppm
200 – 500 (~7 – 0 gpg)
pH (strength of alkalinity)
8.0 – 11.4
SPECIFIC RESISTIVITY
~50k
Ω cm (50,000 ohm-centimeter)
Blow down the boiler on at least a once-a-day basis. If boiler water or feed-water are
outside the above limits, a more frequent blowdown is required.
Water quality can affect efficiency or result in boiler damage if neglected. Boiler feedwater
contains impurities in solution and suspension. These impurities concentrate in the boiler
since the steam generated is essentially pure. The concentration of these impurities
increases as more feedwater is introduced into the boiler and steam is produced. If the
suspended solids are allowed to concentrate beyond certain limits, a deposit or “scale”
will form on the boiler’s internal surfaces. This deposit can interfere with proper boiler
operation and cause boiler failure.
The concentration of these impurities is generally controlled by the feedwater quality and
by blowdown. Blowdown refers to removing a portion of the boiler water with high solids
concentration and replacing it with make-up water of a lower concentration.
Water Quality Information for Carbon Steel Boilers
23
Installation, Operation & Maintenance Manual