Figure 2-20.—Demineralizer.
The inlet supply valve to the demineralizer must
be adjusted on system start-up and periodically there-
after to maintain the correct flow rate through the
flowmeter. Too high a flow rate can damage the car-
tridges. If the flow rate cannot be increased to the
proper rate with the inlet supply valve fully open, you
should check to ensure that the outlet valve is filly
open.
The submicron filter is used to remove small
particles that have a size greater than 0.5 micron from
the coolant flow. If the filter becomes clogged, it also
reduces the flow of coolant, which necessitates a
change of the filter cartridge or filter sheet (the mem-
brane). To change the filter, you must properly posi-
tion the demineralizer valves. If the filter cartridge or
the membrane continually becomes clogged (about
1/2 hour or less after replacement), the usual cause in
the distilled-water system is the presence of bacterio-
logical impurities. Bacteriological impurities intro-
duced into the secondary liquid-cooling system using
distilled water may exist in the demineralizer car-
tridges and/or the whole secondary cooling system. If
the impurities are in the whole secondary cooling sys-
tem, the growth rate in a warmwater environment
could be of a magnitude that exceeds the capability of
the demineralizer. In that case, you must determine
the source and magnitude of contamination. However,
bacteriological contamination in a secondary cooling
system that uses distilled water and ethylene glycol is
highly improbable.
Improper handling or storage of the cartridges
could cause them to be a source of contamination.
Therefore, you should always store the cartridges in a
cool, dry area, as exposure to heat hastens the growth
of any biological contaminates that may have entered
the cartridges. The three types of cartridges are or-
ganic removal, oxygen removal, and mixed bed.
Organic Removal Cartridge: The organic re-
moval cartridge, which contains granulated activated
charcoal (carbon) to remove large organic molecules
and chlorine by adsorption, is always installed in the
first exchanger (if required) to prevent organic mole-
cules from fouling the remaining cartridges.
2-21
