1.1 Methods
Notes:
1. Application: Testing of residual corrosion inhibitors (Oxygen scavengers) in boiler feed
water or condensate.
2. Before using clean the vials with Hydrochloric acid (approx. 20%). Rinse thoroughly with
deionised water.
3. Ideally temperature for full colour development is 25°C ± 3 °C.
4. Volume should always be metered by using suitable pipette (class A).
5. Keep blank and sample dark during colour development time. UV-light (sunlight) causes
high measurement results.
6. Interferences:
• Iron (II) interferes at all concentrations:
Repeat the test procedure but without adding the VARIO DEHA Rgt 2 solution. If the
displayed result is above 20 μg/l subtract this value from the DEHA test result.
• Substances which reduce Iron (III) interfere. Substances which complex iron strongly
may interfere also.
• Substances who may interfere when present in concentrations at:
Borate (as Na
2
B
4
O
7
) 500 mg/l
Cobalt 0.025 mg/l
Copper 8.0 mg/l
Hardness (as CaCO
3
) 1000 mg/l
Lignosulfonates 0.05 mg/l
Manganese 0.8 mg/l
Molybdenum 80 mg/l
Nickel 0.8 mg/l
Phosphate 10 mg/l
Phosphonates 10 mg/l
Sulfate 1000 mg/l
Zinc 50 mg/l
7. There is an option to change the unit from mg/l to μg/l.
mg/l
μg/l
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