13
The Membranes
The membranes need to be cleaned only when feed pressure begins to rise due to fouling or
the product quality degrades. The primary causes of fouling are biological growth and scaling.
Biological growth occurs when the system is left unused without flushing or pickling. Fouling
from mineral scaling will form when the feed water is
“
hard
”
or high in carbonates. Very small
“
colloidal metal
”
and metal oxide particles can also plug the pores in the membrane. Monitor
the product salinity and feed pressure for higher than normal readings for the existing condi-
tions. Other conditions can cause high pressure such as cold feed water or clogged filters. Low
product flow is usually due to low voltage, damaged feed pump or Clark Pump. Look for all
other causes before cleaning the membrane. Membrane life can be shortened by excessive
cleaning.
There are two types of cleaners: acid and alkaline. The acid cleaner (SC
-
3) will remove mineral
scaling. The alkaline cleaner (SC
-
2) is used to remove biological by
-
products, oil, and dirt parti-
cles that get past the prefilters. If membrane performance is reduced and it has not been
“
pickled
”
recently, cleaning with both chemicals is recommended. The acid cleaner should be
used first. Colloidal Metals and Metal Oxides are very difficult to remove. If the membrane
fails to respond to both cleanings, this is an indication of another problem with the system, or
that it is time to replace the membrane. Contact Spectra Watermakers before removing a
membrane.
