This standard applies to all types of water in boiler operation with a total hardness of at least 1.25 nmol/l and at most 10 nmol/l. If more than 2 ng iron(ll) or 400 µg copper(ll) is present in the analysis sample, the determination is impaired. Most other metal ions do not interfere with the described method.
NEN 6549-1988 history
1988NEN 6549-1988 Water for boiler plants Photometric determination of total hardness