Water for Stability Tests

Impact of Water

• prevent spoilage and degradation of the test chamber
• avoid deposit and contamination of the samples 

• Minerals
  Silica, calcium, magnesium and iron are common contaminants that affect the temperature, humidity, irradiance and running costs of Stability Test Chambers (Weathering Test Chambers Application). It is essential that the water, therefore, has low mineral content. Otherwise, the generator’s immersion heater, housing, and float assembly will become encrusted with minerals and cause system failure.
  
  In addition, ions and silica can create deposits on the surface of the samples tested.
  
  Suspended particles, Bacteria (acting as particles, and releasing ions and organics), must be removed to avoid packing and encrustation of the test chamber. 
   
• Organics
  Organics should be removed to avoid a quick spoilage of the test chamber, requiring more frequent maintenance.High-performance VOC (Volatile Organic Compounds) observation chambers have been developed to measure VOC emissions from construction materials, furniture, office equipment, and household appliances. In this case, humidification requires “VOC-free” water, to avoid polluting the samples with extraneous VOCs.
  
  Reverse Osmosis technology, alone or combined with Electro Deionisation is suitable to meet the quality specifications of water required for this application.
  
  The conductivity level after reverse osmosis treatment is in the range 20 to 10 µS/cm which can be suitable for some Stability Test Chambers operation. The level of organics after RO is significantly reduced compared to the level of organics present in tap water. Particles and bacteria are removed by the reverse osmosis membrane and by the depth filter typically used upstream to the RO membrane. When lower ionic contamination is required, the combination of reverse osmosis and electrodeionisation provides water with conductivity below 1µS/cm @ 25°C corresponding to less than 0.5 mg/L ionic contamination. 

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