Setup: Axeon Reverse Osmosis System NL-PRO Series User Manual

Overview

The Reverse Osmosis System NL-PRO Series is a commercial single-pass water treatment system designed to produce high volumes of purified permeate from properly pretreated feedwater. The series includes the NL-PRO 2000 and NL-PRO 4000 models, making it suitable for facilities that need approximately 2,000 to 4,000 gallons of reverse osmosis water per day.

Each system uses a multi-stage stainless steel pump, 4040 reverse osmosis membrane elements, sediment pre-filtration, pressure monitoring, and separate permeate and concentrate connections. Correct feedwater preparation, gradual startup, regular monitoring, and documented maintenance are essential for reliable production and membrane life.

Specifications

• Models: NL-PRO 2000 and NL-PRO 4000
• Configuration: Single pass
• Maximum feedwater TDS: 2,000 ppm
• Standard recovery: 32% for the NL-PRO 2000 and 46% for the NL-PRO 4000
• Permeate production: 2,000 gallons per day (7,570 liters per day) for the NL-PRO 2000; 4,000 gallons per day (15,141 liters per day) for the NL-PRO 4000
• Permeate flow: 1.39 gallons per minute (5.26 liters per minute) for the NL-PRO 2000; 2.78 gallons per minute (10.52 liters per minute) for the NL-PRO 4000
• Minimum concentrate flow: 3 gallons per minute (11.36 liters per minute)
• Feed connection: 3/4-inch FNPT
• Permeate connection: 1/2-inch quick connection
• Concentrate connection: 1/2-inch quick connection
• Membranes: 4040 size; one membrane in each vessel; one total in the NL-PRO 2000 and two total in the NL-PRO 4000
• Nominal TDS rejection: 98%
• Pump: Multi-stage pump with a 1.0-horsepower motor
• Motor speed: 3,480 RPM at 60 Hz
• Electrical options: 110 V, 60 Hz, single phase at 10.6 A, or 220 V, 60 Hz, single phase at 5.4 A
• Approximate dimensions: NL-PRO 2000, 18 x 22 x 55 inches; NL-PRO 4000, 23 x 22 x 55 inches
• Approximate weight: 100 pounds for the NL-PRO 2000 and 110 pounds for the NL-PRO 4000

Detailed Description

Feedwater first passes through a 5-micron polypropylene depth filter. This cartridge removes sediment that could obstruct valves, damage pump components, or foul the membrane surface. The pressure gauges before and after the pre-filter help identify when the cartridge is becoming restricted.

The multi-stage centrifugal stainless steel pump raises the feedwater pressure before it enters the membrane vessel. A low-pressure switch protects the pump by stopping the system when inlet pressure falls below 15 psi. Automatic restart occurs when a steady inlet pressure of at least 35 psi is restored.

Inside the membrane vessel, the AXEON XE3-Series thin-film composite membrane separates dissolved solids and other contaminants from water. The purified stream leaves through the permeate outlet and flow meter, while the concentrated reject stream leaves through the concentrate outlet and must remain unrestricted.

The permeate flow meter displays product-water flow. The pump pressure gauge shows pressure leaving the pump and entering the membrane. A pressure gauge associated with the pre-filtration stage helps compare inlet and outlet pressure across the sediment cartridge.

Membrane Performance

Under the stated test conditions, the systems are designed to provide approximately 2,000 to 4,000 gallons per day at 77°F, with nominal TDS rejection of up to 98%. Actual output changes with feedwater temperature, TDS, pressure, recovery, and pretreatment quality.

Rejection describes the percentage of dissolved solids retained by the membrane. Calculate it by subtracting permeate TDS from feed TDS, dividing by feed TDS, and multiplying by 100.

Recovery describes the portion of feedwater converted into permeate. Calculate it by dividing product-water flow by feedwater flow and multiplying by 100. Feedwater flow equals permeate flow plus concentrate flow, using the same flow units for each measurement.

The XE3-4040 membrane has a polyamide thin-film composite construction, a continuous operating pH range of 4 to 10, and a short-term cleaning pH range of 2 to 12 for up to 30 minutes. Its maximum feed silt density index is 3, maximum feed flow is 14 gallons per minute, and chlorine tolerance is zero.

For a newly installed membrane, increase feed pressure gradually over 30 to 60 seconds. Establish cross-flow gradually over 15 to 20 seconds, avoid sudden hydraulic changes, and discard permeate produced during the first hour of operation. Avoid static pressure on the permeate side and do not allow pressure drop across one membrane vessel to exceed 15 psi.

Safety

• Read and understand the complete operating and service instructions before installing, operating, or maintaining the system.
• Keep all warning, caution, electrical hazard, and identification labels attached to the equipment.
• Do not use the system with microbiologically unsafe or unknown water unless suitable testing and disinfection are completed before or after treatment.
• Before service, switch off the system, close the feedwater supply, release all pressure, and disconnect electrical power.
• Never allow chlorine, chloramines, or other oxidizing agents to reach the membrane. Pretreatment must remove substances that can attack the membrane material.
• Do not operate the system when it is frozen, and do not expose feedwater to temperatures above 85°F.
• Never operate the pump without adequate feedwater flow.
• Do not completely close the concentrate line. A blocked or restricted drain can create backpressure and damage membranes or other components.
• Do not exceed the specified operating pressure, temperature, feedwater limits, or minimum flow requirements.
• Provide a protective earth ground and have electrical connections completed in accordance with applicable electrical codes.

Operating Limits

• Design feed temperature: 77°F
• Feed temperature range: 40°F minimum to 85°F maximum
• Ambient temperature range: 40°F minimum to 120°F maximum
• Feed pressure range: 45 to 80 psi
• Operating pressure range: 70 to 130 psi
• Maximum operating pressure: 200 psi
• Maximum SDI: Less than 3
• Maximum turbidity: Less than 1 NTU
• Free chlorine: Less than 0 ppm; chlorine must not be present
• Maximum TDS: 2,000 ppm
• Maximum hardness: 0 grains per gallon
• Continuous pH: 4 to 10
• Cleaning pH: 2 to 12 for a maximum of 30 minutes

Obtain an up-to-date feedwater analysis before startup. Higher TDS, lower temperature, inadequate pressure, and changing feedwater chemistry can reduce production and affect membrane performance. Conditions outside the stated limits require application-specific evaluation and appropriate pretreatment.

Setup and Operation

Choose an Installation Location

• Provide enough clearance to remove membrane elements and reach all gauges, fittings, filters, valves, and electrical components.
• Place the system near a suitable drain and compatible electrical supply.
• Protect the unit from direct sunlight, freezing temperatures, excessive heat, and high humidity.
• Secure the system in accordance with applicable local requirements.
• Use a feedwater line no smaller than 3/4 inch to help prevent pressure fluctuations.

Connect the Water Lines

1. Connect the feedwater supply to the 3/4-inch FNPT connection marked FEED.
2. Connect the 1/2-inch quick connection marked PERMEATE to a suitable storage tank.
3. Connect the 1/2-inch quick connection marked CONCENTRATE to a drain.
4. Use an air break on the concentrate drain when practical to reduce the chance of siphoning while the system is in standby.
5. Keep the concentrate line open enough to maintain the required minimum flow.

Electrical Connection

The NL-PRO Series is available in 110 V or 220 V, 60 Hz, single-phase configurations. Confirm that the electrical service matches the rating of the installed model. A dedicated circuit is recommended, and the incoming supply must include protective earth grounding.

Initial Startup and Purging

Membrane elements are supplied separately and must be installed before operation. Inspect all plumbing and electrical connections before applying power. Keep the system switched off until the startup sequence calls for operation.

1. Route the permeate line to a drain rather than the storage tank.
2. Move the solenoid-valve lever to the offset bypass position.
3. Open the feedwater supply and allow the system to purge for approximately 5 to 10 minutes.
4. Return the solenoid-valve lever to the inline operating position.
5. Set the system to position 2 and start it.
6. Run the unit continuously for at least one hour to flush preservative from the membranes and inspect for leaks.
7. Stop the system after the flush period.
8. Redirect permeate to the storage tank and restart the system.
9. Record operating readings daily for the first week. After that, continue recording them at least once per week.

Do not use the first-hour permeate for drinking water or food preparation. The permeate pH can be one to two points lower than feedwater pH, so evaluate downstream plumbing materials where low-pH water could be aggressive.

Cleaning and Maintenance

Pre-Filter Replacement

The system is supplied with a 5-micron sediment cartridge. Replace it when the pressure difference between the filter inlet and outlet reaches approximately 10 to 15 psi. For example, if inlet pressure is 60 psi, replace the cartridge when outlet pressure falls to 50 psi or lower.

• Monitor the filter inlet and outlet pressures.
• Replace cartridges on condition rather than allowing severe restriction.
• Never operate the pump with insufficient feed flow.
• Maintain a daily operating log during initial operation and a weekly log thereafter.

Membrane Installation or Replacement

1. Confirm that every pressure gauge reads zero.
2. Switch off the system, disconnect power, close feedwater, and relieve pressure.
3. Disconnect permeate tubing or fittings from the upper end plug.
4. Remove the locking crescents with a 5 mm hex wrench.
5. Thread a 1/2-inch by 6-inch PVC nipple, or a similar tool, into the permeate port and pull the end plug out carefully.
6. Wear clean gloves and place removed components on a clean surface.
7. Remove the old membrane with long-nose pliers.
8. Inspect the new membrane, brine seal, permeate tube, and O-rings for damage.
9. Lubricate the brine seal and O-rings with a non-petroleum lubricant. Do not use petroleum-based lubricant.
10. Apply the same compatible lubricant inside the vessel below the locking-crescent groove.
11. Install the membrane in the direction shown by the vessel flow arrows, with the brine seal correctly positioned.
12. Push the membrane fully down until it seats on the lower end plug.
13. Reinstall the upper end plug without pinching or damaging O-rings.
14. Replace and tighten the locking-crescent screws.
15. Reconnect all fittings and complete the purging procedure before returning permeate to service.

Extended Shutdown and Storage

Do not leave the system shut down for extended periods without preserving the membranes. For storage, fully immerse the membrane elements in a 2% M-100 preservative solution and isolate the solution from outside air by closing the valves. Check the preservative pH weekly and replace the solution when the pH reaches 3 or lower. Repeat the preservation process at least monthly.

Before storage, clean the system with the specified C-10 and C-20 membrane cleaners, flush it with permeate water, and protect the elements with M-100 solution. Completely drain the pressure vessels and plumbing, or fill them with the appropriate propylene-glycol preservation mixture to prevent freezing.

For cold-weather storage, add 10% to 40% propylene glycol by weight after mixing the 2% M-100 solution. A 30% mixture provides freeze protection to approximately 7°F. Never allow residual water in plumbing to freeze.

Temperature Correction

Rated membrane production is based on 77°F water. To estimate output at another temperature, divide the rated permeate flow by the temperature correction factor for the actual feedwater temperature. A temperature correction factor of 1.000 applies at 77°F; colder water produces less permeate, while warmer water produces more.

After applying the temperature correction, measured permeate flow should generally remain within 20% of the corrected rated production. Record feed temperature and flow together in the operating log.

Operating Log

Record the following information during routine monitoring:

• Date, time, and operating hours
• Filter inlet and outlet pressure
• Pump discharge and concentrate pressure
• Feed, permeate, concentrate, and recycle flow
• Recovery percentage
• Feed temperature
• Feed and permeate TDS
• Rejection percentage
• Feed and permeate pH
• Scale inhibitor feed
• Iron, free chlorine, and hardness readings
• Cleaning date, system identification details, and startup information

Troubleshooting

Low Inlet Pressure

• Possible causes: Low supply pressure, plugged cartridge, or a visible leak.
• Corrective actions: Increase or restore inlet pressure, replace the sediment cartridge, and repair leaks.

Low Permeate Flow

• Possible causes: Low operating pressure, cold feedwater, damaged brine seal, fouled membrane, or membrane scaling.
• Corrective actions: Check inlet pressure, apply temperature correction, inspect the brine seal, and clean or replace affected membrane components as appropriate.

High Permeate Flow

• Possible causes: Feedwater temperature above the specified maximum, an oxidized or damaged membrane, or damaged product-tube O-rings.
• Corrective actions: Verify temperature, inspect the membrane, and replace damaged membranes or O-rings.

Poor Permeate Quality

• Possible causes: Damaged or oxidized membrane, metal-oxide fouling, colloidal fouling, scaling, biological fouling, organic fouling, or chlorine exposure.
• Corrective actions: Check dechlorination and pretreatment, improve metal and colloid removal, use the appropriate acid or high-pH cleaning method, reduce recovery when scaling requires it, replace cartridge filters, and correct chlorine-control equipment.

Common Fouling Conditions

• Mineral scaling: Review acid and antiscalant dosing, reduce recovery if necessary, and use a compatible acid cleaner.
• Biological fouling: Review disinfection, dechlorination, biocide strategy, and cartridge-filter condition.
• Organic fouling: Improve activated-carbon or other pretreatment and use the specified high-pH cleaner when suitable.
• Crystalline abrasion: Improve pretreatment and check filters for media leakage.

When escalating a technical problem, have the installation date, serial number, operating readings, feedwater information, pretreatment details, and a precise description of the symptom available.

Warranty

The system warranty covers defects in materials and workmanship for 12 months from the warranty commencement date when the equipment is installed, operated, and maintained within the specified conditions and instructions.

The warranty commencement date is the later of product receipt or installation, provided installation occurs within three months of shipment. Proof of purchase and, when requested, proof of installation may be required.

The warranty remedy is limited to repair or replacement of a component determined to be defective. Disposable items such as fuses, O-rings, regeneration materials, and chemicals are excluded from coverage.

Coverage may be voided by misuse, abuse, accident, unauthorized repair or modification, incorrect installation, operation outside the stated limits, failure to maintain the equipment, use of unauthorized replacement parts, or exposure of membranes to incompatible chemicals, lubricants, chlorine, chloramines, or other oxidizing agents.

Labor, travel, consequential losses, production losses, and incidental or commercial damages are excluded under the stated warranty terms. The warranty provides specific legal rights, which may vary by jurisdiction.

Pros & Cons

• Pros: Two production capacities, single-pass operation, commercial 4040 membranes, stainless steel multi-stage pumping, integrated pressure monitoring, automatic low-pressure protection, and detailed operating-log guidance.
• Cons: Performance depends heavily on correctly conditioned feedwater, chlorine must be completely removed, the concentrate line cannot be restricted, and regular filtration, monitoring, cleaning, and preservation are required.