MIOX RIO-S Series Operators Manual
102-00130-D
Page
72
• Graduated Cylinder (1000 mL for MIOX and RIO Series mixed-oxidant or sodium
hypochlorite systems)
• Timer or a watch with a second hand
• Calculator
Preparing Chlorine Demand-Free Water
Demand-free water is required for determination of oxidant concentration in an on-site
generator. Because the oxidant is being diluted significantly, any demand in the dilution
water will cause a significant misreading in the oxidant concentration. There are two
methods for making demand-free water. The first, and preferred, method requires UV
exposure over an extended period and may not be practical for quick analysis. The second
method is quicker, but the calculations must be modified to account for the excess chlorine
residual in the water.
Note: Distilled water, whether purchased at the store or made in a lab, cannot be
trusted to be demand-free.
Method One:
1. Add 5mL of 5.25% bleach into one gallon of distilled water.
2. Shake to mix thoroughly.
3. Allow the water to sit 2 days inside.
4. After 2 days inside, move the water outside where it will be exposed to direct
sunlight since ultraviolet light reduces chlorine to chlorides.
5. Test a sample for chlorine and allow to sit longer in direct sunlight if chlorine is
still present.
Method Two:
1. Add 3 mL of oxidant solution into one gallon of distilled water.
2. Shake to mix thoroughly.
3. Allow the water to sit for thirty minutes.
4. Check the chlorine residual in the water.
5. If there is no chlorine residual in the water, add another 3 mL, and wait another thirty
minutes.
6. If there is a chlorine residual, record the value and wait another 15 minutes.
