Thermo Scientific STANDARD Series Manual page 22

Section 3 Installation
3-10
Water Quality and Standards
Process Fluid
Microbiologicals
(algae, bacteria, fungi)
Inorganic Chemicals
Calcium
Chloride
Copper
0.020 ppm if fluid in contact with aluminum
Iron
Lead
Magnesium
Manganese
Nitrates\Nitrites
Potassium
Silicate
Sodium
Sulfate
Hardness
Total Dissolved Solids
Other Parameters
pH
Resistivity
* MΩ-cm (compensated to 25°C)
Unfavorably high total ionized solids (TIS) can accelerate the rate of galvanic
corrosion. These contaminants can function as electrolytes which increase
the potential for galvanic cell corrosion and lead to localized corrosion such
as pitting. Eventually, the pitting will become so extensive that refrigerant will
leak into the water reservoir.
As an example, raw water in the United States averages 171 ppm (of NaCl).
The recommended level for use in a water system is between 0.5 to 5.0 ppm
(of NaCl).
Recommendation: Initially fill the tank with distilled or deionized water. Do
not use untreated tap water as the total ionized solids level may be too high.
This will reduce the electrolytic potential of the water and prevent or reduce
the galvanic corrosion observed.
Permissible (PPM)
0
<25
<25
<1.3
<0.3
<0.015
<12
<0.05
<10 as N
<20
<25
<20
<25
<17
<50
6.5-8.5
0.01*
Desirable (PPM)
0
<0.6
<10
<1.0
<0.1
0
<0.1
<0.03
0
<0.3
<1.0
<0.3
<1
<0.05
<10
7-8
0.05-0.1*
Thermo Scientific