FOR OPTIMUM RESULTS, THE FEEDWATER SUPPLY SHOULD BE TESTED PRIOR TO INITIAL STARTUP, 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 BOILER ON AT LEAST A ONCE A DAY BASIS. IF BOILER WATER OR FEEDWATER ARE OUTSIDE THE
ABOVE LIMITS, A MORE FREQUENT BLOWDOWN IS REQUIRED.
RECOMMENDED LIMITS WITHIN A BOILER
TOTAL DISSOLVED SOLIDS, ppm 3500
TOTAL ALKALINITY, ppm 850
SUSPENDED SOLIDS, ppm 300
SILICA (Si0
2
), ppm 125
SULFITE (SO
3
), ppm 25–50
PHOSPHATE, ppm 30–60
P-ALKALINITY AS CaCO
3
, ppm 900
IRON, ppm 2
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 FEED-
WATER 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 INTERNAL SUR-
FACES. 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 CON-
CENTRATION AND REPLACING IT WITH MAKEUP WATER OF A LOWER CONCENTRATION.
Sussman Boilers
Installation, Operation & Maintenance Manual
Water Quality Information for Carbon Steel Boilers
23
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