Vannkvalitet i laboratorier

Contaminant Parameter and unit Type 3 Type 2 Type 1
Ions Resistivity (MΩ•cm @ 25°C) >0.05 >1.0 >18.0
Organics TOC (ppb) <200 <50 <10
Pyrogens (EU/mL) NA NA <0.03
Particulates Particulates > 0.2 µm (units/mL) NA NA <1
Colloids Silica (ppb) <1000 <10 <10
Bacteria Bacteria (cfu/mL) <1000 <100 <1

 

 

International Organization for Standardization (ISO)

The ISO based its specification on ISO 3696:1987, and specifies three grades of water: Grade 1, Grade 2 and Grade 3, where Grade 1 is the most pure (see below):

Water quality parameters for ISO grades

Parameter Grade 1 Grade 2 Grade 3
pH value at 25oC 5.0–7.0
Conductivity (μS/cm)  at 25oC, max 0.1 1.0 5.0
Oxidisable matter Oxygen content (mg/l), max 0.08 0.4
Absorbance at 254 nm and 1 cm optical path length, absorbance units, max. 0.001 0.01
Residue after evaporation on heating at 110oC (mg/kg), max 1 2
Silica (SiO2) content (mg/l), max 0.01 0.02

American Society for Testing and Materials (ASTM)

The ASTM uses D1193-06 and has four grades of water (see table below).

Water quality parameters for ASTM types

Parameter Type I* Type II** Type III*** Type IV
Conductivity (μS/cm) at 25oC, max 0.056 1.0 0.25 5.0
Resistivity (MΩ-cm) at 25oC, max 18.0 1.0 4.0 0.2
pH at 25oC 5.0–8.0
TOC (μg/l), max 50 50 200 No limit
Sodium (μg/l), max 1 5 10 50
Silica (μg/l), max 3 3 500 No limit
Chloride (μg/l), max 1 5 10 50