REVERSE OSMOSIS
INSTALLATION AND OPERATION MANUAL
R12-Wall Mount
IMPORTANT
Please read the entire manual before proceeding with the installation and startup:
Do not use where the water is microbiologically unsafe.
Always turn off the unit, shut off the feed water, and disconnect the electrical power when
working on the unit.
Never allow the pump to run dry.
Never start the pump with the reject valve closed.
Never allow the unit to freeze or operate with a feed water temperature above 100°F.
NOTES
Changes in operating variables are beyond the control of Watts. The end user is responsible for
the safe operation of this equipment. The suitability of the product water for any specific
application is the responsibility of the end user.
Successful long-term performance of an RO system depends on proper operation and
maintenance of the system. This includes the initial system startup and operational startups and
shutdowns. Prevention of fouling or scaling of the membranes is not only a matter of system
design, but also a matter of proper operation. Record keeping and data normalization are
required in order to know the actual system performance and to enable corrective measures when
necessary. Complete and accurate records are also required in case of a system performance
warranty claim.
Changes in the operating parameters of an RO system can be caused by changes in the feed
water or can be a sign of trouble. Maintaining an operation and maintenance log is crucial in
diagnosing and preventing system problems. For your reference, a typical log sheet is included
in this manual.
TABLE OF CONTENTS
I. Introduction
A. Specifications
B. RO Overview
C. Pre-treatment
II. Controls, Indicators, and Components
III. Operation
A. Installation
B. Plumbing Connections
C. Electrical
D. Startup
E. Control Function
F. Operation and Maintenance Log
G. Troubleshooting
IV. Replacement Parts List
V. Membrane Replacement
VI. Appendix
Temperature Correction Factors
I. INTRODUCTION
The separation of dissolved solids and water using RO membranes is a pressure driven
temperature dependent process. The membrane material is designed to be as permeable to water
as possible, while maintaining the ability to reject dissolved solids.
The main system design parameters require the following:
Internal flows across the membrane surface must be high enough to prevent settling of fine
suspended solids on the membrane surface.
The concentration of each dissolved ionic species must not exceed the limits of solubility
anywhere in the system.
Pre-treatment must be sufficient to eliminate chemicals that would attack the membrane
materials.
A. SPECIFICATIONS
Maximum Productivity (Gallons per day)
Quality (membrane rejection) 98 % 98 % 98 % 98 %
Recovery (user adjustable) 15 - 75 % 15 - 75% 15 - 75 % 30 - 75 %
Membrane Size
Number Of Membranes
Prefilter (System ships with one 5 micron cartridge)
Feed Water Connection
Product Water Connection (Tubing OD) 3/8”
Reject Water Connection (Tubing OD) 3/8”
Feed Water Required (Maximum) 2.4 gpm
Feed Water Pressure (Minimum) 10 psi
Drain Required (Maximum) 2.4 gpm
Electrical Requirement
Motor Horse Power
Dimensions W x H x D (approximate inches)
Shipping Weight (estimated pounds)
R12-0150 R12-0250 R12-0600 R12-1200
150 250 600 1200
2.5” x 14” 2.5” x 21” 2.5” x 40” 2.5” x 40”
1 1 1 2
10”
1/2” NPT
120 VAC 60 Hz 8 amps
1/2
22 x 32 x 12 22 x 52 x 12
50 50 60 70
B. RO OVERVIEW
Reverse osmosis systems utilize semipermeable membrane elements to separate the feed
water into two streams. The pressurized feed water is separated into purified (product) water
and concentrate (reject) water. The impurities contained in the feed water are carried to drain
by the reject water. It is critical to maintain adequate reject flow in order to prevent
membrane scaling and/or fouling.
RO Membrane
Feed Water Product Water
Reject Water
C. PRETREATMENT
The RO feed water must be pretreated in order to prevent membrane damage and/or fouling.
Proper pretreatment is essential for reliable operation of any RO system.
Pretreatment requirements vary depending on the nature of the feed water. Pretreatment
equipment is sold separetly. The most common forms of pretreatment are described below.
Media Filter - Used to remove large suspended solids (sediment) from the feed water.
Backwashing the media removes the trapped particles. Backwash can be initiated by time or
differential pressure.
Water Softener - Used to remove calcium and magnesium from the feed water in order to prevent
hardness scaling. The potential for hardness scaling is predicted by the Langelier Saturation
Index (LSI). The LSI should be zero or negative throughout the unit unless approved antiscalents are used. Softening is the preferred method of controlling hardness scale.
Carbon Filter
- Used to remove chlorine and organics from the feed water. Free chlorine will
cause rapid irreversible damage to the membranes.
The residual free chlorine present in most municipal water supplies will damage the thin film
composite structure of the membranes used in this unit. Carbon filtration or sodium bisulfite
injection should be used to completely remove the free chlorine residual.
Chemical Injection
- Typically used to feed antiscalant, coagulant, or bisulfite into the feed water
or to adjust the feed water pH.
Prefilter Cartridge - Used to remove smaller suspended solids and trap any particles that may be
generated by the other pretreatment. The cartridge(s) should be replaced when the pressure drop
across the housing increases 5 - 10 psig over the clean cartridge pressure drop.
The effect of suspended solids is measured by the silt density index (SDI) test. An SDI of five
(5) or less is specified by most membrane manufacturers and three (3) or less is recommended.
Iron & Manganese - These foulants should be removed to less than 0.1 ppm. Special media
filters and/or chemical treatment is commonly used.
pH - The pH is often lowered to reduce the scaling potential. If the feed water has zero hardness,
the pH can be raised to eliminate CO2.
Silica: Reported on the analysis as SiO2. Silica forms a coating on membrane surfaces when the
concentration exceeds its solubility. Additionally, the solubility is highly pH and temperature
dependent. Silica fouling can be prevented with chemical injection and/or reduction in recovery.
I. CONTROLS, INDICATORS, and COMPONENTS (see figure 1)
A. On / Off Switch – Turns the unit on and off.
B. Product Pressure Switch – Automatically turns the unit on and off based on the
product water pressure.
C. Reject Control Valve - Controls the amount of reject flow.
D. Reject Recycle Control Valve – Controls the amount of recycle flow.
E. Prefilter Pressure Gauges (optional) - Indicate the inlet and outlet pressures of the
prefilter. The difference between these two gauges is the prefilter differential
pressure.
F. Pump Discharge Pressure Gauge - Indicates the membrane feed pressure.
G. Reject Flow Meter (optional) - Indicates the reject flow rate in gallons per minute
(gpm).
H. Product Flow Meter (optional) - Indicates the product flow rate in gallons per minute
(gpm).
I. Prefilter Housing - Contains the RO prefilter.
J. Automatic Inlet Valve - Opens when pump is on and closes when the pump is off.
K. RO Feed Pump - Pressurizes the RO feed water.
L. RO Membrane Vessel(s) - Contains the RO membrane(s).
M. Low-pressure indicator.
Figure 1
III. OPERATION
A. INSTALLATION
1. Proper pretreatment must be determined and installed prior to the RO system.
2. The water supply and pretreatment equipment should be sufficient to provide a
minimum of 10-psig at the maximum feed flow.
3. An electrical receptacle with a ground fault interrupt (GFI) is highly recommended.
4. Responsibility for meeting local electrical and plumbing codes lies with the owner /
operator.
5. Install indoors in an area protected from freezing. Space allowances for the removal
of the membranes from the pressure vessels should be provided.
B. PLUMBING CONNECTIONS
Note: It is the responsibility of the end user to ensure that the installation is done according to
local codes and regulations.
1. Connect the pretreated feed water line to the inlet valve (Figure # 1 item J). A feed
water shutoff valve should be located within 10 feet of the system.
2. Temporarily connect the product water outlet to a drain. (The product outlet is
located below the product pressure switch, or on top of the product flow meter,
depending on how the unit is equipped.) The product water line should never be
restricted. Membrane and/or system damage may occur if the product line is blocked.
3. Connect the reject water outlet to a drain. (The reject outlet is located at the reject
needle valve, or on top of the product flow meter, depending on how the unit is
equipped). The reject drain line should never be restricted. Membrane and/or system
damage may occur if the reject drain line is blocked. An air gap must be located
between the end of the drain line and the drain. The use of a standpipe or other open
drain satisfies most state and local codes and allows for visual inspection and
sampling.
4. If a bladder tank is used for product water storage then the product pressure switch
(Figure #1 item B) needs to be connected. Install a tee and tube fitting in the inlet
piping of the bladder tank and connect the tank to the pressure switch using poly
tubing. A check valve should be installed between the RO unit and this tee.
C. ELECTRICAL
Note: It is the responsibility of the end user to ensure that the installation is done according to
local codes and regulations.
1. Make sure the on / off switch is in the off position (Figure # 1 item A).
2. Plug the unit into a standard 120 volt 3 prong outlet. An outlet protected with a
ground fault interrupt (GFI) is recommended.
D. STARTUP
1. Verify that the pretreatment equipment is installed and working properly. Verify that no
free chlorine is present in the feed water.
2. Verify that the on / off switch is in the off position.
3. Install a 10" five micron filter cartridge in the prefilter hou sing.
4. Open the reject control valve completely (Figure # 1 item C) by turning it
counterclockwise.
5. Close the reject recycle control valve (Figure # 1 item D) completely by turning it
clockwise.
6. Open the feed water shutoff valve installed in step III-B-1 above.
7. Move the controller on/off switch to the on position.
8. Allow the unit to run for 15 – 30 minutes to flush the preservative from the membrane(s).
9. Adjust the reject control valves (Figure # 1 items C & D) until the desired flows are
achieved. Closing the reject valve increases the product flow and decreases the reject
flow. Opening the reject recycle valve decreases both the reject and product flow. See
the flow rate guidelines and temperature correction table in the appendix to determine the
flow rates for different operating temperatures. Do not exceed 200 psi on the pump
discharge gauge (Figure #1 item F).
10. Allow the product water to flow to drain for 30 minutes.
11. Turn off the system and connect the product line to the point of use. The product water
line should never be restricted. Membrane and/or system damage may occur if the
product line is blocked.
12. Restart the system and record the initial operating data using the log sheet.
E. CONTROL FUNCTION
1. When the on / of switch is in the on position, the inlet valve opens and the pump runs. If
the product pressure switch is used then the pump will cycle based on the product water
pressure. The switch is factory set to cut off at 40 psi and cut on at 20 psi. Instructions
for adjusting the cut off and cut on pressures are located on the inside cover of the switch.
2. If the water pressure feeding the pump drops below 5 psi for more than 5 seconds, the
pump will turn off and the amber light on the control box will turn on. The controller
will automatically reset after 30 minutes and the pump will turn back on. Cycle the off /
auto switch to manually reset a low-pressure shutdown.
3. Autoflush – This is an optional feature that provides increased reject flow at startup and
for 2 minutes every hour. The timer is preprogrammed at the factory and should not be
adjusted.
F. Operation and Maintenance Log
DATE PRODUCT
GPM
REJECT
GPM
PUMP
DISCHARGE
PRESSURE
FEED
TDS
PPM
PRODUCT
TDS
PPM
FEED
WATER
TEMP
FEED
WATER
HARDNESS
FEED WATER
CHLORINE
LEVEL
PRE FILTER
INLET
PRESSURE
PRE FILTER
OUTLET
PRESSURE
REMARKS
Note: Change the prefilter when the differential pressure increases by 5 - 10 psi over the clean differential pressure.
Clean the RO membrane(s) when the product flow drops by 15% or more. (See appendix)
G. TROUBLESHOOTING
RO MEMBRANE TROUBLE SHOOTING GUIDE
SYMPTOMS
Salt Passage Permeate Flow Pressure Drop Location Possible Causes Verification Corrective Action
Normal to
increased
Normal to
increased
Increased
Normal to
moderate
increase
Decreased or
moderately
increased
Increased Increased Decreased Most severe in
Increased Increased Decreased Most severe in
Increased Normal to
Increased Normal to low Decreased All stages Conversion too
Decreased Normal to
increased
Decreased Normal to
increased
Decreased Increased Predominantly
Decreased Normal to
moderate
increase
Decreased Normal All stages Organic fouling Destructive
Decreased At random O-ring leaks, End
increased
Predominantly
first stage
Predominantly
first stage
last stage
Can occur in
any stage
the first stage
the first stage
Metal oxide Analysis of metal
Colloidal fouling SDI measurement
Scaling
, CaSO3,
(CaSO
4
, SiO2)
BaSO
4
Biological fouling Bacteria count in
Chlorine oxidant
attack
Abrasion of
membrane by
crystalline material
or side seal glue
leaks.
high.
ions in cleaning
solution.
of feed/ X-ray
diffraction
analysis of
cleaning sol.
residue.
Analysis of metal
ions in cleaning
sol. Check LSI of
reject. Calculate
maximum
solubility for
, BaSO4,
CaSO
4
in reject
SiO
2
analysis.
permeate and
reject. Slime in
pipes and vessels.
testing, e.g. IR
reflection
analysis.
Chlorine analysis
of feed.
Destructive
element test.
Microscopic
solids analysis of
feed. Destructive
element test.
Probe test.
Vacuum test.
Colloidal
material passage.
Check flows and
pressures against
design guidelines
Improved pretreatment
to remove metals.
Cleaning with acid
cleaners.
Optimize pretreatment
system for colloid
removal. Clean with
high pH, anionic
detergent formulation.
Increase acid addition
and scale inhibitor for
CaSO
and CaSO4.
3
Reduce recovery.
Clean with an acid
formulation for
, CaSO4 and
CaCO
3
.
BaSO
4
Shock dosage of
sodium bisulfite.
Continuous feed of
low conc. bisulfite at
reduced pH. Peracetic
acid sterilization.
Clean with alkaline
anionic surfactant.
Chlorine dosage upstream with
dechlorination.
Replace cartridge
filters.
Optimization of
pretreatment system
(e.g. coagulation
process.)
Resin/activated carbon
treatment. Clean with
high pH detergent.
Check chlorine feed
equipment and
dechlorination
equipment.
Improved
pretreatment. Check
all filters for media
leakage.
Replace O-rings.
Repair or replace
elements.
Reduce conversion
rate. Calibrate sensors.
Increase analysis and
data collection.
RO SYSTEM TROUBLE SHOOTING
PROBLEM REMEDY
General
High Product Water TDS
Membrane frozen, high temp, or backpressure. Replace membrane.
Membrane attack by chlorine Carbon pre-filter may be exhausted. Replace filter and membrane.
Product seal on end cap. Determine if seal or o-ring is bad. Replace as needed.
No Product Water or Not Enough Product Water
Feed water shut off. Turn on feed water.
Low feed pressure. Feed pressure must be at least 10 psi. Consider booster pump.
Pre-filter cartridge clogged. Replace pre-filter cartridge.
Membrane fouled. Determine and correct cause; replace or clean membrane.
Product check valve stuck. Clean or replace check valve.
Low pump discharge pressure
Low feed water temperature
Adjust reject valve or replace pump
Increase membrane feed pressure or heat the feed water.
IV. REPLACEMENT PARTS LIST
A list of common replacement parts is provided below. Contact your dealer for replacement
parts assistance.
Part Number Description
S9550-D/T Pre filter housing 10"
R9677-SV2514.1 RO membrane pressure vessel 2.5” x 14" SS
R9677-SV2521.1 RO membrane pressure vessel 2.5” x 21" SS
R9677-SV2540.1 RO membrane pressure vessel 2.5” x 40" SS
R2451 Pressure gauge, 2", 0-100 psi, dry, bottom mount
R2456 Pressure gauge, 2", 0-100 psi, dry, back mount
R2461 Pressure gauge, 2 1/2", 0-400 psi, LF
R5126 Flow meter 0.1 – 1.0 gpm
R5129 Flow meter 0.2 – 2.0 gpm
R9852 Product pressure switch
R9852C Product pressure switch with auto / off lever
R2200-120/60 Motor 0.5 HP single phase 120 volt
R2101-140 Pump 140 GPH carbonator with relief valve
R23-1070S Low pressure controller
R23-PS32 Low pressure switch, ¼” MPT, 3 – 40 psi
R2530 Reject & recycle brass needle valve
R2402 Inlet solenoid valve, 1/2”, 120 volt coil
W-2514-TW 2.5” x 14” RO membrane
W-2521-TW 2.5” x 21” RO membrane
W-2540-TW 2.5” x 40” RO membrane
S1025AB Prefilter cartridge, 10”, 5 micron
R9812-4SS Product check valve, SS
V. MEMBRANE REPLACEMENT
1. Turn off the system and close the feed water shutoff valve.
2. Disconnect the tubing from the pressure vessel.
3. Remove the retaining "U" pins from the pressure vessels.
4. Push the old membrane out of the vessel in the direction of the feed flow
5. Record the serial numbers of the new membranes.
6. Lightly lubricate the brine seals on the new membranes with clean water.
7. Install the new membranes in the direction of flow with the brine seal end going in
last.
8. Lightly lubricate the end cap internal and external o-rings with glycerin.
9. Install the end caps and secure them with the "U" pins.
10. Reconnect the tubing to the pressure vessel.
11. Verify that all retaining "U" pins are installed.
12. Follow the start up procedure in section III-D.
Flow Direction
Membrane Brine Seal
VI. APPENDIX
The following tables are intended as a guide to determining the flow rates for the R12
series RO systems. All flows are in gallons per minute (GPM).
Nominal flows for systems operating at 50% recovery.
R12-0150 R12-0250 R12-0600 R12-1200
Product 0.10 0.17 0.41 0.83
Reject 0.10 0.17 0.41 0.83
Temperature Correction Factors
Deg C Deg F Correction Factor
30 86 1.16
29 84.2 1.13
28 82.4 1.09
27 80.6 1.06
26 78.8 1.03
25 77 1.00
24 75.2 0.97
23 73.4 0.94
22 71.6 0.92
21 69.8 0.89
20 68 0.86
19 66.2 0.84
18 64.4 0.81
17 62.6 0.79
16 60.8 0.77
15 59 0.74
14 57.2 0.72
13 55.4 0.70
12 53.6 0.68
11 51.8 0.66
10 50 0.64
9 48.2 0.62
8 46.4 0.61
7 44.6 0.59
6 42.8 0.57
5 41 0.55
Multiply the nominal product flow at 25° C by the temperature correction factor to determine the
flow at various other temperatures.
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