OPERATORS MANUAL
ORION II
Orion II 500-10000 Operators
Page 30 of 95
Manual Part no: DOMAON0100 Issue A
April 2008
5.4.4 Option 42 Twin Pass Reverse Osmosis
The twin pass RO option employs a second RO membrane pass to further purify the water.
It is used on high salinity feed water, feed water containing high concentrations of silica or where
greater process security is desired.
The first pass of a twin pass system is essentially the same as a single pass system with 42
replacing 40 in the item tagging. Permeate form the first pass is fed to the second pass which
provides the final permeate.
Concentrate from the second pass is recycled to TK30-01 via a modulating valve and flow meter
arrangement VA42-03 & FT42-03.
5.5 PURIFIED WATER SYSTEM DEIONISATION SECTION
5.5.1 Option 50 Degassing
Degasser modules (DG50-01, etc) can be supplied as an option to enhance the performance of the
CEDI module where carbon dioxide levels in the feed water are high. This option will be in the form
of 1 2 or 3 modules depending on the Orion model.
The vertically mounted stainless steel degasser module(s) contains thousands of fine hydrophobic
hollow fibres that are impervious to water but allow gases through them. They are potted into end
plates similar in layout to a shell and tube heat exchanger. Water passes through the shell side of
the module and oil-free filtered air (instrument grade) is passed down through the centre of the
hollow fibres to strip carbon dioxide gas from the water.
Permeate from the RO system passes into the bottom connection of the module(s) and out at the top
before passing to an isolation valve (V50-03) and a CIP connection (CIP4).
V50-03 and CIP4 are used to bypass the degasser when the CEDI unit is chemically cleaned with
agents that are non-compatible with the degasser membrane material and cleaning the RO and
degasser units whilst bypassing the CEDI unit.
Air sweep feed pressure and flow rate to the degasser module(s) is regulated and adjusted using
V50-01 & V50-02. Flow and pressure are monitored using FI50-01 and PI50-01. A solenoid valve
(VA50-01) shuts the air supply off when required. A low flow switch FAL50-01 raises an alarm (but
does not cause a shutdown) if the air flow rate on FI50-01 falls below a set minimum during normal
operation.
5.5.2 Option 60 Continuous Electrical Deionisation (CEDI)
A fuller description of the CEDI process is included in the Appendix.
The CEDI system will consist of 1 2 or 3 modules and their associated valves and instruments
depending on the Orion model.
A pressure gauge (P45-01) is located on the inlet to the CEDI module to indicate pressure.
Feed to the CEDI unit(s) is split in two, providing a main stream (or dilute, which is normally
approximately 90% of the feed flow) for purification and a second smaller stream (approximately
