Conversion table ’’water hardness

The total water hardness refers to the total concentration of alkaline earths calcium and magnesium in mmol/1. The concentrations of strontium and barium, which are usually very low, are not considered. The following is valid for conversion to German degress of hardness (°d) 1 mmol/1 hardness = 5.61 °d. Factors for conversion to the degree of hardness of other countries are given in Table 23.2. 

The Langelier saturation index (LSI) is probably the most widely used indicator of a water scale potential. This index indicates the driving force for scale formation and growth in terms of pH as a master variable. In order to calculate the LSI, it is necessary to know the alkalinity (mg L as CaCOj or calcite), the calcium hardness (mg L Ca + as CaCOj), the total dissolved solids (mg L h TDS), the actual pH, and the temperature of the water (°C). If TDS is unknown, but conductivity is, one can estimate mg L" TDS using a conversion table (Table 8.15). LSI is defined as... 

The corrosion of lead in natural waters depends on the hardness of the waters, as evidenced by the data in Table 4.56. The natural waters of moderate hardness (i.e., less than 125 ppm calcium carbonate) tend to be less aggressive due to the formation of a protective film, which is also aided by the presence of silicates. On the other hand, nitrate ions disrupt the protective film and increase the corrosion rate. Corrosion of lead occurs in waters containing carbonic acid due to the conversion of carbonate in the film into... 

Pt-zeolite catalysts were also employed for the selective reduction of NO by HCs and were very active at lower reaction temperatures compared to Fe-, Cu- and Co-zeolites, but little, if any, literature was found for the Pt-exchanged zeolite catalysts deahng with the water tolerance. Iwamoto and coworkers conducted a comparative investigation of Pt- and Cu-MFI and Fe-MOR for their performance in NO reduction by C2H4. Pt-MFI-97 was found to be more active than the other two metal-exchanged zeolite catalysts at low temperatures and its activity for NO conversion at 200"C is hardly alfected by the addition of 8.6% H2O into the feed gas stream (Table 6), whereas the conversion of N2O formed during the course of the reaction slightly decreases by less than 10 /o. In... 

DHA-NVP System. We conducted several copolymerization experiments to high conversion in order to examine some characteristics of the systems and to determine some properties of the formed copolymers. The findings are summarized in Table II. The purified poly (DHA-co-NVP) materials were white, powdery solids completely soluble in water, alcohols, chloroform, DMF, and DMSO and insoluble in acetone, benzene, and ether. The copolymers had good film-forming properties, i.e. air-dried films were clear and hard with a high gloss. 

Drinking Water 987 Table 23.2. Conversion factors for degrees of hardness ... 

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