Humidifier
72 © robatherm
Circulating water spray humidifier (low pressure)
Water quality
Before commissioning, it is necessary to check the quality of fresh and circulating water.
Fresh water
• Analysis of fresh water (can usually be obtained from local public utilities).
• Total water hardness below 7° dH
• Water quality according to VDI 6022, VDI 3803, DIN EN 13053, and the German
Drinking Water Regulation
Circulating water
Limit values for the quality of the circulating water (recommendations according to VDI
3803 and BG Druck und Papierverarbeitung, among others):
Water quality Normal request Data processing
areas
Sterile and clean
rooms
Electr. conduction
(µS/cm)
< 1.000* < 300 < 120**
Carbonate hardness
(° dH)
< 4 < 4 < 4
Chloride (g/m³) < 180 < 180 < 180
Sulfate (g/m³) < 150 < 100 < 100
pH value 7 to 8.5 7 to 8.5 7 to 8.5
Microbial count
(CFU/ml)
< 1,000 < 100 < 10
Legionella
(CFU/100ml)
< 100 < 100 < 100
Cycle of
concentration
2 to 4 2 to 6*** 2 to 8***
Table 7: Water quality of the circulating water
CFU = Colony Forming Units
*) Softening or partial desalination may be necessary; electrical conduction
max. 800 µS/cm when humidifying to above 95 %r.H.
**)
Full desalination necessary
***)
Lower value without additional disinfection measures; upper value with
additional measures
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