Instructions for Deionizing Unit
DEI.010

The pack contains sufficient resin to fill the deinonizing tube 12 times.

1. Fill the deionizer plastic tube up to the 135mm mark with deionizer resin. Tap the tube on the bench to pack down the resin.
2. Place one of the cotton wool pads on top of the resin column.
3. Suspend the tube under the tap of a gravity water filter or other source of filtered water. The end of the tap should be centrally located above the resin column and sufficiently inside the tube to prevent any non-deionized water trickling down the outside of the tube.
4. Place a plastic water collecting container on a stool or crate below the deionizer tube. Insert a plastic funnel in the neck of the bottle to collect the deionized water.
5. Slowly turn on the tap of the water filter to obtain a trickle of water.
6. Important: For satisfactory deionization the water must pass through the resin column slowly and evenly. It will take about 1 hour to obtain 4-5 litres of water.
7. If the water is allowed to pass through the column rapidly it will form a channel through or down the side of the resin instead of passing evenly through the entire resin bed. Uneven passage of the water will be indicated by the resin changing colour unevenly down one side of the column. If this is noticed unhook the tube from the tap and turn it the other way round.
8. When about 75% of the resin column appears red, check the conductivity reading of the deinonized water using an appropriate meter such as the Hanna Pure Water Test meter (DEI.040). When a meter is not available, discard the resin when there remains only about 20mm of light brown resin in the bottom of the tube. At this point the conductivity of the water will read around 20 µSm/cm. Discard exhausted resin and refill with fresh batch.

Maintenance of the deionizer resin.

This deinozing unit allows laboratory staff to prepare pure water when it is needed and in the amounts required at a much lower cost than most commercial resin cartridge units. To maximize the life of the resin the following are important:

• Keep the deionizer tube out of sunlight to avoid inactivating the indicator.
• When not in use, remove the deionizer tube and store it in a dark place. This will protect the indicator and also minimize contamination of the resin column. When first used after storage, discard the water passing through the column for the first 5 minutes.
• Keep unused resin in an opaque, sealed, airtight plastic bag or tin.

Safety precautions.

Deionizer resin can cause irritation if it is allowed to enter the eye or skin. It is therefore advisable to wear plastic gloves and protective eye goggles when filling the plastic tube. The resin beads are insoluble in water. Store the resin below 50¼C away from nitric acid and strong oxidisers.

Expected output figures.

Based on water previously filtered through a Berkefeld filter the following are the deionized water output figures that may be expected from 150g (one column fill) of resin for soft, medium and hard water:

Soft (about 50 mg/t.d.s): 55-65 litres

Medium (about 200 mg/t.d.s): 15-17 litres

Hard (about 300 mg/ t.d.s): 11-12 litres

(Note: t.d.s = total dissolved solids)

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