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CONDITION
Scaling Potential — Primary Measurement
Above the given limits, scaling is likely to occur. Scaling indexes should be calculated using the limits below.
pH/Calcium Hardness Method
Index Limits for Probable Scaling Situations (Operation outside these limits is not recommended.)
Scaling indexes should be calculated at 150
Ryznar Stability Index
Langelier Saturation Index
Iron Fouling
Iron Fe
2+
(Ferrous)
(Bacterial Iron Potential)
Iron Fouling
Corrosion Prevention
d
pH
Hydrogen Sulfide (H
S)
2
Ammonia Ion as Hydroxide,
Chloride, Nitrate and Sulfate
Compounds
Maximum Chloride Levels
Erosion and Clogging
Particulate Size and Erosion
Brackish
NOTE(S):
a. Heat exchanger materials considered are copper, cupronickel, 304 SS (stainless steel), 316 SS, titanium.
b. Closed recirculating system is identified by a closed pressurized piping system.
c. Recirculating open wells should observe the open recirculating design considerations.
d. If the concentration of these corrosives exceeds the maximum allowable level, then the potential for serious corrosion problems exists. Sulfides in the water quickly oxidize
when exposed to air, requiring that no agitation occur as the sample is taken. Unless tested immediately at the site, the sample will require stabilization with a few drops
of one Molar zinc acetate solution, allowing accurate sulfide determination up to 24 hours after sampling. A low pH and high alkalinity can cause system problems, even
when both values are within ranges shown. The term pH refers to the acidity, basicity, or neutrality of the water supply. Below 7.0, the water is considered to be acidic.
Above 7.0, water is considered to be basic. Neutral water registers a pH of 7.0. To convert ppm to grains per gallon, divide by 17. Hardness in mg/l is equivalent to ppm.
LEGEND
HWG —
Hot Water Generator
HX
—
Heat Exchanger
Design Limits Not Applicable Considering Recirculating
N/A
—
Potable Water
NR
—
Application Not Recommended
SS
—
Stainless Steel
Table 3 — Water Quality Guidelines
HX
CLOSED
a
MATERIAL
RECIRCULATING
All
N/A
°
F for direct use and HWG applications, and at 90
All
N/A
All
N/A
All
N/A
All
N/A
6 - 8.5
All
Monitor/treat as needed.
All
N/A
All
N/A
Copper
N/A
Cupronickel
N/A
304 SS
N/A
316 SS
N/A
Titanium
N/A
<10 ppm of particles and a
maximum velocity of 6 fps.
All
Filtered for maximum
800 micron size.
All
N/A
OPEN LOOP AND RECIRCULATING WELL
b
pH < 7.5 and Ca Hardness, <100 ppm
°
F for indirect HX use. A monitoring plan should be implemented.
If >7.5 minimize steel pipe use.
If <–0.5 minimize steel pipe use.
°
Based upon 150
F HWG and direct well, 85
2+
If Fe
(ferrous) >0.2 ppm with pH 6 - 8, O
Above this level deposition will occur.
Minimize steel pipe below 7 and no open tanks with pH <8.
At H
S>0.2 ppm, avoid use of copper and cupronickel piping or HXs.
2
Rotten egg smell appears at 0.5 ppm level.
Copper alloy (bronze or brass) cast components are okay to <0.5 ppm.
Maximum allowable at maximum water temperature.
°
°
50
F (10
C)
<20 ppm
<150 ppm
<400 ppm
<1000 ppm
>1000 ppm
<10 ppm (<1 ppm "sandfree" for reinjection) of particles and a maximum
velocity of 6 fps. Filtered for maximum 800 micron size. Any particulate that
is not removed can potentially clog components.
Use cupronickel heat exchanger when concentrations of calcium or sodium
chloride are greater than 125 ppm are present. (Seawater is approximately
25,000 ppm.)
10
c
6.0 - 7.5
–0.5 to +0.5
°
F indirect well HX.
<0.2 ppm (Ferrous)
<5 ppm check for iron bacteria.
2
<0.5 ppm of Oxygen
6 - 8.5
<0.5 ppm
<0.5 ppm
°
°
75
F (24
C)
100
NR
NR
<250 ppm
<150 ppm
<550 ppm
<375 ppm
>550 ppm
>375 ppm
°
°
F (38
C)
NR
NR
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