DPD No. 4 Rapid Tablets for Total Chlorine

Overview

DPD No. 4 rapid tablets complete the chlorine picture. Used after a free chlorine tablet on the same sample, they develop the colour for total chlorine, and the difference between the two readings is the combined chlorine — the chloramine fraction that points to ammonia in the water. On a potable system that difference is often the first sign that breakpoint chlorination is not being reached.

Key features

• Gives total chlorine, and combined chlorine by difference from the free reading
• One tablet per test, so there is no measuring or decanting of liquid reagents
• Foil-sealed strips keep unused tablets dry until they are needed
• Supplied in the standard 250-tablet pack, item code TbSRD4250

DPD No. 4 rapid tablets specifications

Applications

Potable water and SANS 241 compliance monitoring, wastewater effluent disinfection, cooling water carrying ammonia, pools tracking chloramines, and troubleshooting taste and odour complaints.

Why buy DPD No. 4 rapid tablets from Hadron Group

Hadron Group supplies water treatment chemicals, dosing equipment and analytical products throughout South Africa and the SADC region. We hold DPD No. 4 rapid tablets as standard stock in the 250-tablet pack, we can supply the matching photometer, cuvettes and spares, and our technical team will help you settle on the right test set for your plant. Browse the full reagent range or ask us for a quote.

Frequently asked questions

Why does combined chlorine matter?
Combined chlorine is chlorine bound to ammonia and organics. It disinfects poorly and carries the familiar chlorine smell, so a rising combined figure usually means a higher dose or a shock treatment is due.

Rapid grade or photometer grade — which do I need?
The rapid-dissolving grade is made to break up by hand for comparators, colour discs and pool testers. Use the photometer grade in an instrument that reads a cuvette, and keep to one grade so your readings stay comparable.

How should the tablets be stored?
Keep them sealed, cool and dry, and work through the oldest strip first. Once a strip is opened the tablets take up moisture, so use them promptly.