Resolution: Theory of operation
In the electrode humidifier, current flowing between the electrodes in the water generates the heat necessary to boil the water and the amperometric transformer (TAM) regulates electric current in the humidifier by controlling water level and mineral concentration in the steam cylinder. This is accomplished by opening and closing the feed water solenoid valve and the cylinder electric drain valve. When steam is needed, the humidifier contact is closed, providing power to the immersed electrodes. When the current falls below the value required as a result of the fall in the water level, the feed water solenoid valve is opened.
The cylinder electric drain valve is opened at intervals depending on the characteristics of the feed water supply in order to maintain the optimum concentration of dissolved minerals in the water in the cylinder.
Feed water
Values for the feed water for medium-high level of conductibility of a humidifier with immersed electrodes:
Limits
Description
Units
Minimum
Maximum
Hydrogen ion activity pH
-
7
8.5
Specific conductibility at 20°C σ R, 20°C
μS/cm
300
1250
Total dissolved solids TDS
mg/l
(1)
(1)
Residual fixed at 180°C R180
mg/l
(1)
(1)
Total hardness TH
mg/l
100(2)
100
Temporary hardness
mg/l
60(3)
300
Iron + manganese
mg/l Fe + Mn
0
0.2
Chlorides
ppm Cl
0
30
Silica
mg/l
0
20
Residual chloride
mg/l
0
0.2
Calcium sulphate
mg/l
0
100
Metallic impurities
mg/l
0
0
Solvents, diluents, soaps, lubricants
mg/l
0
0
(1) Values dependent on the specific conductibility; in general: TDS @ 0,93 * s20; R180 @ 0,65 * s20
(2) Not lower than 200% of the Chloride content in mg/l di Cl-
(3) Not lower than 300% of the Chloride content in mg/l di Cl-
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