AAON RN Series, Installation Operation & Maintenance, Page: 121 / 136

121
Appendix A - Heat Exchanger Corrosion Resistance
Corrosion Resistance of Copper and Stainless Steel in Brazed Plate Heat Exchangers
- Points to Measure and Check in a Water Analysis
The resistance guide provides the corrosion resistance of stainless steel type AISI 316 and pure
Copper (99.9%) in water, to a number of important chemical factors. The actual corrosion is a very
complex process influenced by many different factors in combination.
Explanations: + Good resistance under normal conditions
0 Corrosion problems may occur especially when more factors are valued 0
- Use is not recommended
Water
Containing
Concentration
(mg/l or ppm) Time Limits -
Analyze Before
AISI
316
SMO
254
Copper
Alloy
Nickel
Alloy
Alkalinity
(HCO
3
-
)
< 70
Within 24
Hours
+ + 0 +
70-300 + + + +
> 300 + + 0/+ +
Sulfate (SO
4
2- )
< 70
No Limit
+ + + +
70-300 + + 0/- +
> 300 0 0 - +
HCO
3
- / SO
4
2-
> 1.0
No Limit
+ + + +
< 1.0 + + 0/- +
Electrical
Conductivity
< 10µS/cm
No Limit
+ + 0 +
10-500 µS/cm + + + +
> 500 µS/cm + + 0 +
pH
< 6.0
Within 24
Hours
0 0 0 +
6.0-7.5 0/+ + 0 +
7.5-9.0 + + + +
> 9.0 + + 0 +
Ammonium
(NH
4
+
)
< 2
Within 24
Hours
+ + + +
2-20 + + 0 +
> 20 + + - +
Chlorides (Cl - )*
< 300
No Limit
+ + + +
> 300 0 + 0/+ +
Free Chlorine
(Cl
2
)
< 1
Within 5 Hours
+ + + +
1-5 + + 0 +
> 5 0/+ + 0/- +
Hydrogen
Sulfide (H
2
S)
< 0.05
No Limit
+ + + +
> 0.05 + + 0/- +
Free
(aggressive)
Carbon Dioxide
(CO
2)
< 5
No Limit
+ + + +
5-20 + + 0 +
> 20 + + - +
*See Chloride Content Table