Based on internal research testing and consultation with water purification experts, Q-Lab has harmonized the requirements for all QUV, Q-SUN, and Q-FOG tester models, with only two exceptions (Q-SUN spray, QUV non-spray, and Q-FOG CRH models), as shown below. These guidelines are intended to prevent water spotting on test specimens, buildup of mineral scale deposits, and corrosion of test chambers and plumbing systems.
|
Tester Model
|
Resistivity
(Ω-cm)
|
Conductivity
(µS/cm)
|
Total Dissolved
Solids (ppm)
|
Colloidal
Silica (ppm)
|
pH
|
|
QUV/basic, se and cw
|
ordinary tap water is OK
|
|
Q-SUN spray and Q-FOG CRH
|
> 5 M
|
< 0.2
|
< 0.1
|
< 0.1
|
6-8
|
|
All other tester models
|
> 200 k
|
< 5
|
< 2.5
|
not specified
|
6-8
|
Additionally, Q-Lab strongly recommends the use of water purification systems that use reverse osmosis in addition to deionization (RO/DI systems). These systems are not expensive or difficult to operate, and are effective at removing colloidal silica that can cause water spotting on some test specimens. An RO/DI system can be more effective and economical over time than a two-stage deionization system with a Type 1 anion resin, which Q-Lab previously recommended.
In addition to the water purity specifications presented above, Q-Lab also recommends that customers use a water recirculation system wherever possible, to avoid standing water.
For more information, please see Q-Lab’s Technical Bulletin LW-6049 “The Importance of Water Purification for Weathering and Corrosion Testers.” This document is available on q-lab.com and includes detailed information on our research on water purity.