4"x40" | 1950 GPD | 99.6% Salt Rejection | Seawater RO Membrane | Applied Membranes

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AMI 4x40 Seawater Desalination Reverse Osmosis Membranes
For Watermakers and Land-and-Sea Based Seawater Desalinators

Highest Salt Rejection Seawater RO Watermaker Membranes

AMI high rejection and high productivity seawater reverse osmosis membranes are specially designed for marine applications. AMI SWRO membranes are ideal for seawater desalination in shipboard applications, watermakers, land-based desalinators and sea-based desalinators. AMI Membranes are Made in the USA in their ISO 9001:2015 Certified Facility and are 100% Quality and Performance Tested.

Looking for a replacement seawater desalination membrane element for your watermaker filter system? View our Watermaker Replacement Membrane Chart.

Specifications for SWRO Membranes for Watermakers


Benefits of AMI Seawater Desalination RO Membranes:

  • Convert seawater into drinking water on yachts, boats, cruise ships, off-shore platforms, and resorts
  • High Rejection & Flow Rate 
  • Made in the USA 
  • Manufactured in ISO 9001:2015 Certified Facilities 
  • 100% Performance and Quality Tested 
  • High Quality for Consistent and Reliable Performance
  • Uses the most advanced membrane film technology and manufacturing processes
  • Standard dimensions to fit in commonly available housings
Genuine AMI Membranes ISO USA Quality

M-S4040A Specifications

AMI Model Number M-S4040A
Can Replace Models:

DOW SW30-4040,
DuPont SW30-4040,
FilmTec SW30-4040,
Spectra FT-MB-SW4x40,
Industry-Standard 4x40 Size Seawater RO Elements
Size (Approximate): 4" Dia. x 40"L
Flow Rate: 1950 gpd (7.38 m³/d)
Applied Pressure: 800 psig (55 bar)
Stabilized Salt Rejection: 99.6%
Minimize Salt Rejection: 99.4%
Single Element Recovery: 8%
Exterior: Hard Shell Fiberglass
Membrane Type:
Polyamide Thin-Film
For Use in Systems:

Watermakers or marine systems using 4x40 SWRO Membranes

Katadyn Spectra Systems:
Spectra Farallon 1800c,
Spectra Farallon 2800c,
Spectra LB 1800,
Spectra LB 4000

Permeate flow and salt rejection based on 32,000 ppm NaCl feed stream, pressure and recovery listed above.  Element Permeate flow may vary +/- 20%

M-S4040A Operating Limits

Maximum Operating Temperature: 113°F (45°C)
Maximum Operating Pressure: 1,000 psig (69 bar)
Maximum Pressure Drop: 15 psig (1 bar)
Maximum Feed Flow Rate: 16 gpm (3.6m³/h)
pH Range, Continuous Operation: 2-11
pH Range, Short-Term Cleaning: 1-13
Maximum Feed Silt Density Index: SDI 5
Fere Clorine Tolerance: 0


Related Products for use with M-S4040A Seawater Elements

40E100-1 4x40 Fiberglass Membrane Housing for Seawater RO Membranes (Water Maker Pressure Vessel)
C-C2510-A11 Membrane Cleaning Cartridge with Acid Cleaner to Remove Scale Buildup and Prolong Membrane Life
C-C2510-A22 Membrane Cleaning Cartridge with Alkaline Cleaner to Remove Organics and Prolong Membrane Life
C-C2510-A88  Membrane Preservative Cartridge for Preserving the System and Membrane During Extended Periods of Non-Operation.
655139-03 Oil Absorbing Filter Cartridge - Oil-Water Separator Replacement Cartridge, 20" Big Blue Pentair Pentek  Filter
H-F10100CF Plankton Filter  - 10" Standard 100 Micron Spun Polypropylene Replacement Filter Cartridge

Common Applications for AMI Seawater Watermaker Elements:

  • Seawater Desalination
  • Marine Applications
  • Watermaker RO Systems
  • Yachts

Physical Dimensions of AMI M-S4040A SWRO Marine Element

Reverse Osmosis Membrane Dimensions  
L 40.0 (1016)
I 38.0  (960)
D 3.9 (99)
P 0.75 (19)

Replacement Compatibility for AMI 4 x 40 SWRO Membranes

AMI 4040 membrane elements are may be used as direct replacements for most industry-standard 4" x 40"  seawater Membrane elements, including:  DOW FilmTec SW30-4040, Katadyn Spectra FT-MB-SW4x40 , and most other Industry-Standard 4x40 Size Seawater RO Elements - for use in any system using these membrane elements.  Some common systems using these elements are:

  • Spectra Farallon 1800c
  • Spectra Farallon 2800c
  • Spectra LandBased 1800 (Spectra LB 1800)
  • Spectra LandBased 4000 (Spectra LB 4000)
  • Katadyn Farallon 1800c
  • Katadyn Farallon 2800c
  • Katadyn LandBased 1800 (Katadyn LB 1800)
  • Katadyn LandBased 4000 (Katadyn LB 4000)
  • FL-1800c-110-12, FL-1800c-110-24, FL-1800c-220-12, FL-1800c-220-24, FL-1800c-24
  • FL-2800c-220-12, FL-2800c-220-24
  • LB-1800M, LB 1800 M, LB 1800 F, LB-1800F
  • LB 4000 M, LB-4000M, LB 4000 F, LB-4000F

If you do not see your system listed or wish to learn more about compatibility, please contact us.  Our certified water treatment experts will be happy to discuss your application.  To ensure prompt and accurate information, please include as much information about your system as possible, such as:  model, manufacturer, model of membranes being replaced, any available. product manuals or literature associated with your system, and photographs of your system or membranes.