Seawater Quality; Pre-Filtration; Air Bubbles; Chemicals - Danfoss iSave 40 Series Operation Manual

Operation guide | iSave 40
16

5.8 Seawater quality

5.8.1 Pre-filtration

It is important that the incoming water is filtered
properly to assure optimum service life of the
iSave. A true graded density melt-blown depth
filter cartridge rated at 3 μm is therefore recom-
mended. Poor pre-filtration of the feed water will
result in reduced service life of the iSave.
The iSave may request a different pre-filter
of the seawater than the HP pump and
other components in the RO system.
It is important with selection of a proper
filter housing to ensure good cartridge
end sealing. If there is a high risk of water
by-pass it is recommended to use a second
stage filter solution.
As the various filters on the market differ
greatly, Danfoss High Pressure Pumps
recommends using cartridges with
consistent, reliable performance and
high efficiency, in which fibres are blown
continuously onto a central support core.
Danfoss High Pressure Pumps does not
recommend cartridges requiring any type
of binders or resins.
Filters can be purchased from Danfoss
High Pressure Pumps.
For more information on the importance of
proper filtration, please consult our publication
"Filtration", 521B1009, which also will provide you
with an explanation of filtration definitions and
guidance on how to select the right filter. See
section 5.8.1 for filter installation instructions.

5.8.2 Air bubbles

Large bubbles in a pressurised RO system can
result in damage to piping and equipment. All air
must be bled from both the LP and HP before the
RO system is pressurised. Special consideration
should also be given to air bubbles in feed flow,
continuously fed into the HP pump and iSave.
180R9239 | AQ299555093252en-001601 | iSave 40 | 09.2022

5.8.3 Chemicals

The iSave should not be exposed to chemicals
that will damage the RO membranes.

5.9 Initial start up and flushing

Prior to the initial start-up, all piping associated
with the iSave unit should be thoroughly flushed
to assure that no impurities enter the iSave.
Inadequate pre-flushing will strongly affect the
life of the iSave and may lead to its eventual
breakdown.
It is recommended to disconnect all connections
to the iSave and to thoroughly flush the piping
before the iSave is connected to the inlet and
outlet connections.
It is recommended to install temporary basket
strainers at both inlets to the iSave during the
initial start-up and commissioning.
It is essential that the water used for the
final pre-flush is pre-filtered to a level
described in chapter 5.8
Also see "Instruction for start and stop of the
SWRO with iSave unit" in appendix 10.1.
5.10 Initial start-up and settings of safety
equipment
The high-pressure pump that feeds water into
the high pressure line may be able to generate a
pressure higher than the maximum allowable
pressure in the system. There is thus a risk of
personal injury and/or damage to the iSave.
Depending of the type and size of the feed
pump of the RO system, this pump may be able
to generate a pressure higher than the maximum
allowable pressure in the LP system. There is thus
a risk that the iSave or the LP equipment could
be damaged by over-pressurisation.