Rotek RA Series User manual

1
MODELS
RA800
RA1500
RA2000
RA3000
RA4500
RA6000
USER’S MANUAL
Reverse Osmosis System
RA Series

2
Table of Contents
Introduction 3
Safety 5
Labelling 5
Feedwater specifications 6
System Specifications 7
System Component Identification 8
System Flow Schematic 9
Unpacking and Installation 10
Installation Procedure 11-12
Start up and Operation 13-14
Microprocessor Controller and TDS Readout 15
Troubleshooting 16
Appendix 1 Membrane Cleaning 17-20
Appendix 2 Sample operations log 21
Appendix 3 Sample analysis request format 22
Warranty and Guarantee 23
Notes 24

3
Introduction
Your compact commercial Rotek reverse osmosis system is a durable piece of equipment which,
with proper care and maintenance will last for many years. These systems are part of a family
of reverse osmosis units designed for operation with fresh feedwaters having TDS values below
1,500ppm. Models are available with permeate outputs of between 150 and 1,000 litres/hour
as shown in the specification tables.
Common features to these systems include:
≈High pressure stainless steel braided flexible hose lines
≈Flow meters for permeate (treated product) and reject (waste) streams
≈Liquid filled pressure gauges for feedwater pressure and membrane discharge pressure
≈Automatic membrane flush (with feedwater) at start-up and every 24 hours continuous
operation
≈304 grade stainless steel perimeter frame with rubber isolation feet
≈Integrated microprocessor-based controller with display for TDS and system status
≈Feedwater inlet cartridge filter
≈Feedwater inlet solenoid valve
≈Low feedwater pressure sensor with automatic shutdown
≈High pressure SS membrane pressure vessels
≈High performance, low pressure membranes
≈Adjustable pressure regulating valve

4
Options are available for:
≈Reject recirculation to recirculate some of the waste stream and improve recovery rates
≈CIP provision for semi-automated membrane cleaning
≈CIP station to simplify membrane cleaning
≈Chemical dosing systems for automation of pre-treatment
≈Automatic backwash sediment removal filters
≈Automatic backwash carbon and de-chlorination systems
≈Automatic water softeners for mineral hardness reduction.
≈415VAC 3 phase power operation
This User’s Manual outlines installation, operating, maintenance, and troubleshooting details
vital to the reliable performance of your system.
The systems are designed to operate at pressures between 760 and 1520 kPa (110-220psig)
unless otherwise stated. The expected recovery rate with fresh feedwater below 1,500ppm
TDS is between 15%-75%. Lower TDS feedwaters will allow higher recovery rates without a
significant deterioration in membrane performance of operating life. A reject recirculation
facility is available to improve system, recovery rates should feedwater quality permit this.
A current and comprehensive feedwater analysis is essential and should be obtained prior to
system commissioning. This will assist in selecting the correct pre-treatment, chemical dosing
and RO membrane selection. A typical water analysis of what is required is shown in the
Appendix.
If your system is re-adjusted on-site after commissioning, or if the feed water quality changes,
please contact your local dealer or distributor to determine the revised operating conditions
and recommendations for conversion efficiencies to best suit these new conditions.
NOTE: In order to maintain any warranty, an operating log must be maintained as per the
included sample sheet. Copies must be sent to your local dealer or distributor for review.
NOTE: Prior to operating or servicing this system, this User’s Manual must be read and fully
understood. Keep this manual and other associated information for future reference and for
new operators or qualified personnel who may use the system at a future date.

5
Safety
The Safety section of this User’s Manual outlines the various safety headings used throughout
this manual as shown below:
NOTE: Indicates statements that provide further information and clarification.
CAUTION: Indicates statements that are used to identify conditions or practices that could
result in equipment or other property damage.
WARNING: Indicates statements that are used to identify conditions or practices that could
result in injury or loss of life. FAILURE TO FOLLOW WARNINGS COULD RESULT IN SERIOUS
INJURY OR EVEN DEATH.
All electrical works should be performed by a licensed electrician and conform to all relevant
electrical safety regulations
All plumbing works should be performed by a licensed plumber and conform to relevant
plumbing codes.
Labelling
Do not under any circumstances remove any Caution, Warning, or other descriptive label from
the system.

6
Feed Water Specifications
General Feed Water Requirements
Feedwater quality, pressures and flow rates have a significant impact on the performance of
any reverse osmosis system. To ensure reliable and consistent long-term performance, it is
important to supply feed water having the minimum specifications detailed below. If your
feedwater supply is marginal, you should consider using a feedwater break tank and booster
pump to supply the system.
FEED WATER SPECIFICATIONS (minimum)
Hardness
<1 ppm
Hydrogen Sulphide
0 ppm
Free Chlorine
0 ppm
Manganese
<0.05 ppm
Total Dissolved Solids
<1,500 ppm
Organics
<1 ppm
Turbidity (SDI)
<5
Temperature
+5 to +40°C
pH
3-11
Silica
<1.0 ppm
Iron
<0.01 ppm
Pressure
>300 kPa
These specifications should be met in order to have the reverse osmosis system perform
optimally. All operation specifications are based on the test conditions listed below.
RO OPERATION SPECIFICATIONS
Min. Working Pressure
240kPa (35 psi)
Max. Pressure
1700 kPa (250 psi)
Min. NaCl % Rejection
96%
Max. NaCl % Rejection
99%
Min. Feed (lpm)
5
Max. Feed (lpm)
50
Max. Hardness
1.0 ppm
pH Range
3 – 11
Max. TDS
10,000 ppm
Max. Temperature
40°C (105°F)
TEST CONDITIONS: Permeate flow and salt rejection based on 1500 ppm NaCl, 1034kPa
(150psi), 77°F (25°C), pH 6.5-7.0, and recovery of 15%.
NOTE: Higher TDS and/or lower temperatures will reduce the system’s production

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System Specifications
Systems for raw water TDS value below 1,500 ppm
Model RA800 RA1500 RA2000 RA3000 RA4500 RA6000
Permeate Flow
[GPD/LPH]
800 / 150 1500 / 250 2000 / 350 3000/500 4500 / 750 6000 / 1000
Dimensions (LWH) [cm] 60*48*155 60*48*155 60*48*155 69*63*147 69*63*147 69*63*147
Weight (approx.) [kg] 35 62 70 88 94 100
Element Size [in.] 4” x 21” TFC 4” x 40” TFC 4” x 40” TFC 4” x 40” TFC 4” x 40” TFC 4” x 40” TFC
Elements [qty.] 1 1 1 2 3 4
High Pressure Pump Procon Pump
LPE2-11
Multistage
Pump
LPE2-11
Multistage
Pump
LPE2-11
Multistage
Pump
LPE2-11
Multistage
Pump
LPE2-11
Multistage
Pump
Voltage 110V~410V 220V~410V 220V~410V 220V~410V 220V~410V 220V~410V
Hertz 50/60
Operating pressure [kPa] 760-1520 (adjustable)
Pre-filtration (standard) 20" filter housings x 3pcs, 5μm & 1μm PP elements and carbon cartridge
RO Membrane Vessel High pressure SS304 end port type, 2100 kPa (300 PSI) rating
Flow Meters RO permeate and Reject streams (optional for recirculation)
Pressure Gauges Feedwater, membrane discharge (optional for pump discharge)
Electrical controls Micro-processor based, overload breakers, LED indicators, TDS monitor
System Protection Low feedwater pressure sensor, Automatic membrane flush, Inlet feedwater solenoid valve
Power 220-240VAC 50hZ single phase (optional 415VAC 3 phase)
Frame AISI 304 grade stainless steel, electro polished

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System Component Identification
11
10
15
09
14
01
02
03
12 04
05
07
13
08 06
01
02
03
04
05
07
13
06
12
08
11
10
15
09
14
01
02
03
04
05
07
06
12
09
08
11
14
10
15
Front Front
Front
Back Back Back
No.
Component
Part Number
1
Inlet Pressure Gauge
ON/OFF
2
RO Outlet Pressure Gauge
CBMC3T220VHS
3
Power Switch
GP35B25
4
Needle Valve (Concentrate Water Regulator)
GP07B25
5
Permeate Water Flow Meter
SMNV12F
6
Computer Programmed T.D.S. Controller
CMSNPS203
7
Concentrate Water Flow Meter
CSVNC04
8
Low Pressure Protection Switch
P02507
9
Electromagnetic Protection Switch
GF-CRI/CRN
10
Solenoid Valve
CSWHNO
11
Pre-Filters
FRP4040-300
12
RO Membrane + Vessel
GFMDLZB05-CH
13
Rotary Van Pump
GFMDLZB02-CH
14
1HP Motor
HFET2034BL+F0CHO5-20
15
Auto Flush Valve
NC04

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System Flow Schematic
Raw Water Inlet
S
Inlet
Solenoid Valve
20”Pre-Filter
Inlet Pressure
Gauage Low Pressure
Switch
High Pressure
Pump
RO Membrane Module
Neede Valve
Permeate
Flow Meter
Concentrate
Flow Meter
S
Flush
Solenoid Valve
Drain Drain
Product Water Outlet
Recovery Valve
Optional features not shown here include:
•Reject (concentrate) recirculation valve
•Reject recirculation flow meter
•CIP connections
•Chemical dosing connections

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Unpacking and Installation
Packing List
1Reverse Osmosis System
2½” Flexible PE Tubing (5 m)
3Filter Housing Spanner
4Operating Manual
Check that all components are present and in an undamaged condition. If anything is missing
or appears damaged, notify your supplier immediately.
Installation Notes
1Before installation, check that the power supply available matches the power requirements
of the system. Most units are supplied as standard for 220-240VAC 50Hz single phase
operation. Options are available for 415V AC 3 phase power.
2Ensure that all plumbing connections for the feed water inlet, permeate, concentrate and
membrane flush outlets are secure and conform to relevant plumbing regulations.
3Ensure that power lead is rated to carry the current draw of the system. A minimum
electrical wire diameter of 3.5mm is recommended.
4The external storage tank level contact switch should be connected to the blue wires
labelled for tank connection and located inside the electrical cabinet. Do not apply power to
these wires as the connection is designed for a simple non-powered contact type closure
switch only.
5Use an external pressure booster pump if the feedwater pressure is below 150kPa.
6If your feedwater supply is marginal, use a feedwater storage tank and booster pump to
supply the RO system and prevent system cycling.

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Installation Procedure
01
02
03
04
Step 1
Connect the pre-
treated feedwater source to the
inlet solenoid valve using a ¾” mal
e thread coupling.
Use Teflon tape and leak sealant as necessary to
ensure a leak-proof connection.
Step 2
Connect a length of ½”
flexible PE tubing to the fitting
on the rear of the front panel labelled ‘Concentrate’
.
Run this tubing to a nearby tun
dish to drain. There
must be an air gap between the open end of the
tubing and the tundish to prevent suck-
back. The
discharge point must be below the level of the outlet
connection and within 2 metres of the installation.
Step 3
Connect a length of ½”
flexible PE tubing to the fitting
at the rear of the front panel labelled ‘Permeate’
.
Run this tubing into the treated water (permeate)
storage tank.
Step 4
Connect a length of ½”
flexible PE tubing to the
outlet of the membrane flush solenoid valve
and run
this to drain via a tundish as described in step 2. The
tundish may be shared with the ‘Concentrate’
stream.

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Step 5
Take the blue wire from the wiring loom inside the
electrical box and connect this to the float level
sensor in the permeate storage tank. This allows
the RO to turn on and off automatically according
to the treated water storage tank level. Note that
this connection is a contact closure only. Do not
apply any power at any time to these connections.
Step 6
Connect the power supply to the contact breaker
inside the electrical box. Ensure that the available
power matches the power requirements of the
system and that the power cables are rated to
carry the current load of the system.

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Start Up and Operation
System Operation Notes
1. Ensure that feedwater pressure is a minimum of 140kPa (20psi).
2. Check that your feedwater supply flow rate is sufficient for your particular model
3. Check that the available power supply matches your unit requirements.
4. Re-check all installation instructions and that all plumbing and electrical connections have
been made correctly and are secure.
System Operation
01
02
03
Step 1
Loosen the breather valve(s) on top of
the filter
housing(s) to release any air pressure that may
build-up when the system is started up.
This step will generally only have to be performed at
initial start-up or where air may have entered the
feedwater supply line.
Step 2
Turn the power switch on the front panel ON. This
will open the inlet solenoid valve and allow
pressurised feedwater to enter the filter housing(s).
Once any trapped air has been vented from the
filter housings, close the breather valve(s) on the
filter housings.
Step 3
Once the unit is switched ON, it will go into an
automatic membrane flush cycle for 40 seconds.
During this time the feedwater inlet solenoid valve
will remain open, the membrane flush solenoid
valve will open and the RO pressure pump will run.
While t
he membrane flush cycle is operating, the
LCD will show a countdown from 60 to 0 seconds
and all indicator lights will flash.

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.
06
06
Under most operating conditions the ratio between permeate flow and reject flow is between 1:1
and 1:3 and this ratio will vary according to feedwater quality. The normal operating pressure on
the system is around 1050kPa.
NOTE: The system will automatically enter a membrane flush mode for 60 seconds after continuous
operation for 24 hours. This is to remove any sediment build-up that may have occurred on the
membrane surface. The system will continue to operate normally after this process has finished.
Step 4
After the membrane flush cycle is complete, the unit
will
close the membrane flush solenoid, check that
sufficient feedwater pressure is available and go into
normal operating mode
Step 5
If the system detects no error condition, normal
operation will continue. If an error is detected, the
system will shut down until the error condition is
rectified. See “Troubleshooting”
section for more
information.
Step 6
Open the pressure regulator valve by fully turning
anticlockwise. When the system starts up, check flow
rates and operating pressures for permeate and reject
streams. Close the pressure regulator valve slowly
until
the RO outlet pressure gauge reads 700kPa.
Check system flow rates. Adjust the operating
pressure gradually until specified system permeate
flow rate is reached. Use the minimum pressure
possible for desired performance. Ensure that the
operating press
ure on the RO outlet pressure gauge
does not exceed the maximum specified for the
system (generally 1400kPa).
Membrane pressure and flow rates
may also be
altered by opening or closing the RO pump outlet
valve. This valve is located on the discharge side of
the pump. Close the valve slowly to reduce the
overall system output and membrane pressure.

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Microprocessor Controller and TDS Readout
Display Description
Status Lamps
Full Alerts operator when the permeate storage tank is full. The light will turn
green and the RO system will stop automatically.
Flush This lamp is red while the system is going through an automatic membrane
flush cycle
Purify This lamp is green while the system is operating normally and treating
feedwater.
Inlet This lamp is green whenever the power is on. If there is insufficient
feedwater pressure, this lamp will turn on and off every second to alert the
operator to a fault.
Manual Whenever the Flush button is pressed, this light will appear red and remain
red until the membrane flush cycle is complete.
Control Switch Functions
Switch This button switches the display between operation time (1=10 minutes, 99-
990 minutes) and permeate TDS value.
Flush This button may be pressed to initiate a membrane flush cycle while the
system is in normal operation. After the 60 second membrane-flush cycle
normal system operation will resume.
Reset This button may be used to reset the operating time to zero.

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RO TROUBLE SHOOTING GUIDE
SYMPTOMS
Location
Possible
Causes
Verification
Corrective Action
Salt Passage
Permeate Flow
Pressure
Normal to
increased
Decreased
Normal to
increased
Predominantly
first stage.
Metal oxide
scaling.
Analysis of metal
ions in the
feedwater. Check
suitability of
chemical dosing
solution
Improved
pretreatment to
remove metals.
Membrane cleaning
with acidic cleaners.
Normal to
increased
Decreased
Normal to
increased
Predominantly
first stage.
Colloidal
fouling.
Feedwater SDI
and/or X-ray
diffraction analysis of
cleaning solution
residue.
Optimize pre-
treatment system for
colloidal removal.
Clean with high pH,
anionic detergent
formulation.
Increased
Decreased
Increased
Predominantly
last stage.
Scaling due to
chemical
precipitation
(CaSO4, CaSO3,
BaSO4, SiO2).
Analysis of metal
ions in cleaning
solution.
Check LSI of reject
stream. Calculate
max solubility for
CaSO4, BaSO4, and
SiO2 in reject
analysis.
Increase acid addition
and scale inhibitor for
CaSO3and CaSO4.
Reduce recovery.
Clean with an acidic
solution formulation
for CaCO3, CaSO4and
BaSO4.
Normal to
moderate
increase
Decreased
Normal to
moderate
increase.
Can occur in
any stage.
Biological
fouling.
Bacteria count in
permeate and reject
streams.
Slime build-up in
pipework and
pressure vessels.
Shock dosage with
Sodium bisulphite.
Continuous feed of low
concentration of
bisulfate at reduced
pH. Clean with alkaline
anionic surfactant.
Consider upstream
Chlorine dosage and
pre-RO dechlorination.
Replace cartridge
filters.
Decreased
or
moderately
increased
Decreased
Normal
All stages.
Organic
fouling.
Destructive testing of
membrane, e.g. IR
reflection analysis.
Optimization of
pretreatment system
(e.g. flocculation or
coagulation stage).
Resin/activated carbon
treatment. Clean with
high pH detergent
Increased
Increased
Decreased
Most severe in
the first stage.
Chlorine based
oxidant attack.
Chlorine analysis of
feedwater.
Destructive element
test.
Check chlorine feed
equipment and
efficiency of
dechlorination steps.
Increased
Increased
Decreased
Most severe in
the first stage.
Abrasion of
membrane by
crystalline
material.
Microscopic solids
analysis of
feedwater.
Destructive element
test.
Improved pre-
treatment stages
Check all filters for
media leakage.
Increased
Normal to
increased
Decreased
At random.
O-ring leaks in
pressure
vessel.
End or side seal
glue leaks.
Probe test of
pressure vessel and
membranes.
Vacuum test.
Colloidal material
passage.
Replace O-rings.
Repair or replace
elements.
Increased
Normal to low
Decreased
All stages.
Conversion too
high.
Check flows and
pressures against
design guidelines.
Reduce conversion
rate.
Calibrate sensors.
Increase analysis and
data collection.
Troubleshooting

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Appendix 1
Membrane Cleaning
Periodic cleaning of the membrane(s) can improve system performance. In normal
operation, mineral scale, biological matter, colloidal particles, and organic substances can
foul the membranes and reduce performance. The best prevention is to use a well-designed
pre-treatment system incorporating efficient sediment removal, de-chlorination (if chlorine-
based sanitisers are present), and softening or chemical dosing for the removal of scale
forming minerals.
WARNING: Cleaning chemicals are dangerous and can cause injury and damage to the
environment. It is the user’s responsibility to comply with all applicable federal, state, and
local regulations.
General Safety Precautions
1. When using any chemical indicated here in subsequent sections, follow accepted safety
practices. Consult the chemical manufacturer for detailed information about safety,
handling and disposal.
2. When preparing cleaning solutions, ensure that all chemicals are dissolved and well
mixed before circulating the solutions through the membrane elements.
3. It is recommended the membrane elements be flushed with good-quality chlorine-free
water after cleaning. Permeate water is recommended; but a de-chlorinated potable
supply or pre-filtered feedwater may be used, provided that there are no corrosion
problems in the piping system. Operate initially at reduced flow and pressure to flush
the bulk of the cleaning solution from the elements before resuming normal operating
pressures and flows. Despite this precaution, cleaning chemicals will be present on the
permeate side following cleaning so divert the permeate stream to drain for at least 10
minutes or until the water is clear when starting up after cleaning.
4. During recirculation of cleaning solutions, the temperatures must not exceed 50°C at pH
2-10, 35°C at pH 1-11, and 30°C at pH 1-12.

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Organic Foulant Cleaning
The following cleaning procedures are designed specifically for membranes that have been
fouled with organic matter. Review the general cleaning instructions for information that is
common to all types of cleaning such as suggested equipment, pH and temperature limits,
and recommended flow rates.
Cleaning Procedures for organic fouling
1. Prepare the cleaning solution as listed below.
Organic Fouling Cleaning Solution
* Preferred 0.1% (wt) Soda Ash
pH 12, 30°C maximum
* Alternative solution 0.1% (wt) NaOH 0.025% (wt)
pH 12, 30°C maximum
Notes:
1 (wt) Denotes weight percent of active ingredient.
2 Cleaning chemical symbols in order used: NaOH is sodium hydroxide.
2. Low-flow rate pumping. Pump mixed, preheated cleaning solution into the vessel at a
low flow rate of 5-10 litres per minute at low pressure (<120kPa) to displace the process
water. Use only enough pressure to compensate for the pressure drop from feed to
concentrate. The pressure should be low enough so that little to no permeate is
produced. A low pressure minimizes re-deposition of dirt on the membrane. Dump the
concentrate, as necessary, to prevent dilution of the cleaning solution.
3. Re-circulate. After the process water is displaced, cleaning solution will be present in
the concentrate stream and this can be recycled to the cleaning solution tank. Recycle
the cleaning solution for 15 minutes or until there is no visible colour change. If a colour
change occurs, dispose of the cleaning solution and prepare a new solution as described
in step 2.
4. Soak. Turn the recirculation pump off and allow the elements to soak for 1-15 hours
(soaking overnight will give best results). To maintain temperature during an extended
soak period, use a slow recirculation rate (2-5 litres per minute). Soak time will vary
depending on the severity of the fouling. For lightly fouled systems, a soak time of 1-2
hours is sufficient.
5. High-flow pumping. Recirculate the cleaning solution through the membranes at 15-20
litres per minute for 45 minutes. This high flow rate flushes out the foulants removed
from the membrane surface by the cleaning. If the elements are heavily fouled, using a
higher flow rate is possible up to the maximum pressure drop across the membrane
permissible (check with membrane manufacturer’s data sheets). With higher flow rates,
excessive pressure drop may be a problem. The maximum recommended pressure
drops for most common membranes are 100kPa per element or 340 kPa per multi-
element vessel, whichever value is more limiting.

19
6. Flush out. Clean RO permeate water is preferred for this stage. If clean RO permeate
water is not available, pre-filtered raw water can be used for flushing out the cleaning
solution unless there will be corrosion problems (e.g., stagnant seawater will corrode
stainless steel piping). To prevent precipitation of any remaining contaminants, the
minimum flush out temperature is 20°C. The system should be flushed for 1 hour.
7. Re-start the system. The RO elements and the system need to stabilize before taking
any performance data. The stabilization or normalisation period will vary depending on
the severity of the fouling. To regain optimum performance, it may take several
cleaning and soak cycles.
Inorganic Foulant Cleaning
The following cleaning procedures are designed specifically for membranes that have been
fouled with inorganic matter. Review the general cleaning instructions for information that
is common to all types of cleaning such as suggested equipment, pH and temperature limits,
and recommended flow rates.
Cleaning Procedures for inorganic material fouling
1. Make up the cleaning solution listed from Table 1.
Inorganic Cleaning Solution
* Preferred 2.0% (wt) Citric Acid PH 2, 45°C maximum
* Alternate Muriatic Acid
* Alternative 1.0% Na2S2O4
Notes:
1. (wt) denotes weight percent of active ingredient.
2. Cleaning chemical symbols in order used: HCI is hydrochloric acid (Muriatic Acid).
2. Low-flow rate pumping. Pump mixed, preheated cleaning solution into the vessel at a
low flow rate of 5-10 litres per minute at low pressure (<120kPa) to displace the process
water. Use only enough pressure to compensate for the pressure drop from feed to
concentrate. The pressure should be low enough so that little to no permeate is
produced. A low pressure minimizes re-deposition of dirt on the membrane. Dump the
concentrate, as necessary, to prevent dilution of the cleaning solution.
Vessel
3. Re-circulate. After the process water is displaced, cleaning solution will be present in
the concentrate stream that can be recycled to the cleaning solution tank. Recycle the
cleaning solution for 10 minutes or until there is no visible colour change. If at any time
during the circulation process there is a change in pH or a colour change, dispose of the
solution and prepare a new solution as described in step 2. A pH of 2 must be
maintained for the cleaning to be effective.
4. Soak. Turn the pump off and allow the elements to soak. Soak the elements for 1-15
hours (soaking overnight will give best results). To maintain temperature during an
extended soak period, use a slow recirculation rate (2-5 litres per minute). Soak time
will vary depending on the severity of the scaling. For lightly scaled systems, a soak time
of 1-2 hours is sufficient.

20
5. High-flow pumping. Feed the cleaning solution at 15-20 litres per minute for 45 minutes.
The high flow rate flushes out the foulants removed from the membrane surface by the
cleaning. If the elements are heavily fouled, using a higher flow rate is possible up to the
maximum pressure drop across the membrane permissible (check with membrane
manufacturer’s data sheets). With higher flow rates, excessive pressure drop may be a
problem. The maximum recommended pressure drops for most common membranes
are 100kPa per element or 340 kPa per multi-element vessel, whichever value is more
limiting.
6. Flush out. Clean RO permeate water is preferred for this stage. If clean RO permeate
water is not available, pre-filtered raw water can be used for flushing out the cleaning
solution unless there will be corrosion problems (e.g., stagnant seawater will corrode
stainless steel piping). To prevent precipitation of any remaining contaminants, the
minimum flush out temperature is 20°C. The system should be flushed for 1 hour
7. Re-start the system. The RO elements and the system need to stabilize before taking
any performance data. The stabilization or normalisation period will vary depending on
the severity of the fouling. To regain optimum performance, it may take several
cleaning and soak cycles.
NOTE: These recommendations are specific for the ROTEK membrane elements used in
these reverse osmosis systems and may not be compatible with other brands of membrane
elements. It is your responsibility to ensure the suitability of these recommendations and
procedures if they are applied to membrane elements other than those which come with
your system.
Additional Information
Never recirculate the cleaning solution for longer than 20 minutes. With longer recirculation,
the carbonate scale can re-precipitate and end up back on the membrane surface, making it
more difficult to clean. Carbonate scale reacts with HCl releasing carbon dioxide gas.
Depending on the severity of the fouling, it may take repeated cleanings to remove all the
scale. Cleaning severe scale may not be economical and element replacement may be the
best choice.
Citric acid was originally used as a cleaner for cellulose acetate membranes and is not as
effective with thin film composite chemistry. Furthermore, it has a disadvantage of being a
nutrient source for systems which have biological fouling. I t is, however, easier to handle
than HCl and is included as an alternative cleaner for that reason.
NOTE: No freedom from any patent, design registration or copyright owned by Seller or
others is to be inferred. Because conditions of use and applicable laws may differ from one
location to another and may change with time, the end-user is responsible for determining
whether products and the information in this document are appropriate for their needs and
for ensuring that their workplace and disposal practices are in compliance with applicable
laws and other governmental regulations. Seller assumes no obligation or liability for the
information in this document. NO WARRANTIES ARE GIVEN; ALL IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE ARE EXPRESSLY EXCLUDED.