MANOWNROSM
SYSTEM MAINTENANCE
US Filter
21
If the cleaning solution becomes highly discolored during recirculation,
discard it and repeat the application. If any cleaning solution becomes
highly discolored during the first application, the soak and flush method
may be more applicable.
2.
Soak and Flush Method
Pump the cleaning solution into the RO system, soak the cartridges for
15 to 60 minutes, then flush the unit to drain. Flush the system until the
cleaning solution exiting the system is clear, or nearly clear. Repeat soak
and flush cycles until discolored solution is no longer being flushed from
the system. Use this method when the recirculation method is not
effective.
3.
Flush Residual Cleaning Agents Using Reduced Pressure
Flush the cleaning chemical from the system, starting with a 10 to 15
minute manual flush cycle. Then place the system in the operate mode,
and for the first ten minutes, reduce the feed pressure to approximately
half of the normal operating pressure by opening the reject throttle valve.
This prevents residual foulants from being impacted into the membrane.
After ten minutes, return the system to normal operating pressure, and
continue flushing until the product water is clear of all residual cleaning
agents.
I.
Testing for Residual Cleaning Agents After Flushing
Use the following guidelines to determine if the system is clear of residual
cleaning agents.
1.
Acids and Bases
The pH of the product water would be equal to, or nearly equal to, the pH
of the feed water.
2.
Sodium Bisulfite
The conductivity of the product should be equal to, or less than, the
conductivity of the product before cleaning.
3.
EDTA/Na-EDTA
The conductivity of the product should be equal to, or less than, the
conductivity of the product water before cleaning. If the guidelines for
residual EDTA in the product water are more stringent, use the Hach
Model ED-3 EDTA test kit. For ordering information call the number
provided on the cover of this manual.
Table 4-2: Cleaning Solutions for Polyamide Thin Film Composite Membranes.
