Water Quality
Parameter
HX
Material
Closed
Recirculating
Open Loop and Recirculating Well
Scaling Potential - Primary Measurement
pH/Calcium Hardness
All
-
pH < 7.5 and Ca Hardness <100ppm
Method
Index Limits for Probable Scaling Situations -
(Operation outside these limits is not recommended)
Ryznar
All
-
6.0 - 7.5
Stability Index
If >7.5 minimize steel pipe use.
Langelier
All
-
-0.5 to +0.5
Saturation Index
If <-0.5 minimize steel pipe use. Based upon 66°C HWG and
Direct well, 29°C Indirect Well HX
Iron Fouling
Iron Fe
2+
(Ferrous)
All
-
<0.2 ppm (Ferrous)
(Bacterial Iron potential)
If Fe
2+
(ferrous)>0.2 ppm with pH 6 - 8, O2<5 ppm check for iron bacteria.
Iron Fouling
All
-
<0.5 ppm of Oxygen
Above this level deposition will occur .
Corrosion Prevention
pH
All
6 - 8.5
6 - 8.5
Monitor/treat as
needed
Minimize steel pipe below 7 and no open tanks with pH <8
Hydrogen Sulfide (H
2
S)
All
-
<0.5 ppm
At H
2
S>0.2 ppm, avoid use of copper and copper nickel piping or HX's.
Rotten egg smell appears at 0.5 ppm level.
Copper alloy (bronze or brass) cast components are OK to <0.5 ppm.
Ammonia ion as hydroxide, chloride,
nitrate and sulfate compounds
All
-
<0.5 ppm
Maximum
Maximum Allowable at maximum water temperature.
Chloride Levels
10
$
C
24
$
C
38 C
Copper
Cupronickel
-
<20ppm
NR
NR
-
<150 ppm
NR
NR
304 SS
-
<400 ppm
<250 ppm
<150 ppm
316 SS
-
<1000 ppm
<550 ppm
< 375 ppm
Titanium
-
>1000 ppm
>550 ppm
>375 ppm
Erosion and Clogging
Particulate Size and
Erosion
All
<10 ppm of particles
and a maximum
velocity of 1.8 m/s
Filtered for maximum
841 micron [0.84 mm,
20 mesh] size.
<10 ppm (<1 ppm "sandfree” for reinjection) of particles and a maximum
velocity of 1.8 m/s. Filtered for maximum 841 micron 0.84 mm,
20 mesh] size. Any particulate that is not removed can potentially
clog components.
Notes:
Rev.: 4/6/2011
15
Application not recommended.
1RGHVLJQ0D[LPXP
&ORVHG5HFLUFXODWLQJV\VWHPLVLGHQWLILHGE\D
closed pressurized piping system.
5HFLUFXODWLQJRSHQZHOOVVKRXOGREVHUYHWKHRSHQUHFLUFXODWLQJGHVLJQFRQVLGHUDWLRQV
Above the given limits, scaling is likely to occur. Scaling indexes should be calculated using the limits below
Scaling indexes should be calculated at 66°C for direct use and HWG applications, and at 32°C for indirect HX use.
A monitoring plan should be implemented.
Table 4: Water Quality Standards
Water Quality Standards
17
R e s i d e n t i a l S p l i t U n i t s - 6 0 H z P u r o n
®
R e v. : 6 D e c . , 2 0 1 1
