8 ANALYTICAL AND LABORATORY EQUIPMENT
Pure, made
SIMPLE
Mark Bosley explains all you need to know about choosing and operating a reverse osmosis water purifi cation system
Mark Bosley explique tout ce que vous devez savoir pour
choisir et exploiter un système de fi ltration de l’eau par osmose inverse
Mark Bosley liefert Ihnen alle Informationen, die Sie für die Auswahl und Bedienung einer Trinkwasserauf- bereitungsanlage durch Umkehr- Osmose benötigen
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W
ater is one of the most important raw materials used in
the laboratory. Modern reverse osmosis water purifi cation technology can provide a reliable source of pure and ultrapure water, but the best quality and value for money requires care in specifi cation, operation and maintenance. T e chemical composition of raw water even when drawn direct from mains supplies can vary considerably in terms of the quantity and the variety of dissolved minerals, particulate matter and organics. Water contamination comes
from a number of diff erent sources, and the importance of eliminating these diff erent types of contaminant will vary depending on the specifi c equipment and processes in use in the lab. Manufacturers of lab water
purifi cation equipment typically design their systems to meet one of the established European and international standards for water quality, such as ISO 3696 or ASTM D1193-06. T e ISO standard defi nes three basic categories of water: Grade 3, or RO water, for general use, such as washing glassware; Grade 2, or deionised water, for most standard applications; and Grade 1, or ultrapure water, for critical applications where a high level of purity is required. T e ASTM standard categorises water from Type IV, for general use, to Type I for very high purity applications. T e required level of purity in the standards is based on the measurement approach used to determine the level of these diff erent types of contaminants. Ions increase the ability of the water to conduct electricity, for example, so are measured by determining the conductivity of the water. In purer water, due to the lack of ions, its inverse, resistivity, is used. While tap water may have a conductivity
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