２１
3. Description and Function of Each Part
Principle of Operation
(6) TOC Reduction system
The TOC reduction system consists of returning the distilled water stored in the distilled water tank,
via TOC reduction UV, deaeration membrane module, distilled water quality electrode, and
circulation return check valve, to the distilled water tank by means of the distilled water sampling
pump.
With LED (the second LED from the bottom, which corresponds to the water amount of about 5.5
liters) indicating the distilled water level in the tank going ON in green, the TOC reduction system is
activated, starting circulation. Almost simultaneously with passage of the distilled water through the
deaeration membrane module, the deaeration vacuum pump is activated. The electric conductivity
of deaerated distilled water decreases. When the electric conductivity of distilled water in the tank
exceeds
0.83μS
／
cm, the TOC reduction UV lamp goes ON. The TOC value decreases along with
increase in this electric conductivity. When the electric conductivity increases above 0.95μ
Ｓ
/cm, the
TOC reduction UV lamp goes OFF. Then, the distilled water is sampled. Circulation and vacuum
pumps stop when the level LED (the LED in the bottom, which corresponds to thwater amount of
about 2.5 liters). Under other conditions, both circulation and vacuum pumps are in operation
normally while the TOC reduction UV lamp goes ON/OFF depending on the conditions. In this
manner, the distilled water quality in the tank can be maintained.
To protect the vacuum pump (VP), the pump is open to the atmosphere for five minutes every two
hours by means of the solenoid valve. In this case, VP exhaust sound may become louder.