30
Understanding of water hardness and other values
Puckorius Saturation Index (PSI)
PSI = 2
pH
s
-
pH
eq
For PSI index calculation, we recommend water analysis including the following parameters:
pH
s
= 9.3 + A + B - C – D (Edstrom)
A = (log(TDS)-1)/10
TDS (mg/l or ppm)
B = (-13.12 x log(T+273))+34.55
Water temperature T (ºC)
C = log([Ca
2+
]) – 0.4
Calcium hardness or Calcium concentration, [Ca
2+
] (ppm as
CaCO
3
)
D = log(TAC)
TAC (ppm as CaCO
3
)
pH
eq
= 1.465 x log(TAC) + 4.54
TAC (ppm as CaCO
3
)
°dH
°eH
°fH
°aH
ppm as CaCO
3
1°dH
1
1.253
1.79
1.04
17.8
1°eH
0.798
1
1.43
0.83
14.3
1°fH
0.559
0.702
1
0.58
10
1°aH
0.96
1.2
1.71
1
17.1
1 ppm as CaCO
3
0.056
0.072
0.1
0.058
1
Useful conversions
Regional units
Total Alkalinity (TAC)
ppm as CaCO
3
ppm as HCO3
mmol/l
1 mmol/l
50
61
1
1 pmm as CaCO3
1
1.22
0.02
1 ppm as HCO
3
0.82
1
0.0164
ppm as CaCO
3
mmol/l
1 mmol/l
100
1
1 pmm as CaCO3
1
0.02
1 ppm as HCO
3
0.82
0.0164
Total Hardness (TH)
Calcium hardness of Calcium concentration [Ca
2+
]
Calcium hardness can be expressed in mmol/l or mg/l
1 mmol/l of [Ca
2+
] = 1/40 mg/l of [Ca
2+
]
Conductivity (TDS)
1000 μS/cm = 1mS/m
1 μS/cm
~
(1.62 ppm CaCO3 = 1.62 mg/l de CaCO
3
)
Summary of Contents for EvaPack Series
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