4"x21" | 800 GPD | 99.4% Salt Rejection | Watermaker | FilmTec Seawater Membrane

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Brand DOW Filmtec
This product has been discontinued by the manufacturer and is no longer available. We recommend Applied Membranes M-S4021A which can be used as a direct replacement.
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This product has been discontinued by the manufacturer and is no longer available. We recommend Applied Membranes M-S4021A which can be used as a direct replacement.

DOW FilmTec Membrane Elements

DOW FILMTEC™ SW30-4021 Seawater RO Elements for Watermakers and Marine Systems

DOW FILMTEC SW30-4021 elements have one of the highest flow rates available to meet the water demands of both sea-based and land-based desalinators. Commonly used in on-board Watermakers to create drinking water from seawater for yachts, boats, and cruise ships, DOW FILMTEC marine SWRO elements offer the highest productivity while maintaining excellent salt rejection.  DOW FILMTEC SW30 elements may also be operated at lower pressure to reduce pump size, cost, and operating expenses

DOW FILMTEC SW30-4021 is FDA – 21 CFR 177.2550; Food and Drug Administration Compliant.

Product Specifications


FilmTec Membranes are FDA Compliant     Genuine DOW FilmTec Membrane Element   



Specifications for SW30-4021

FilmTec Product: SW30-4021
FilmTec Part Number: 80740
Size (Approximate): 4" Dia. x 21"L
Flow Rate: 800 gpd (3.0 m³/d)
Applied Pressure: 800 psig (55 bar)
Stabilized Salt Rejection: 99.4%
Exterior: Hard Shell Fiberglass
Active Membrane Surface Area: 33 sq. ft.
Membrane Type:
Polyamide Thin-Film

Permeate flow and salt rejection based:  32,000 ppm NaCl feed stream, 77°F,5% recovery, 800 psig.

Operating Limits for SW30-4021

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 (1.4m³/h)
pH Range, Continuous Operation*: 2-11
pH Range, Short-Term Cleaning**: 1-13
Maximum Feed Silt Density Index: SDI 5
Fere Clorine Tolerance***: <0.1ppm

*Maximum temperature for continuous operation above pH 10 is 95°F
**Refer to cleaning guidelines.
***Under certain conditions, the presence of free chlorine and other oxidizing agents will cause premature membrane failure. Since oxidation damage is not covered under warranty, Dow recommends removing residual free chlorine by pretreatment prior to membrane exposure.

Related Products for use with SW30-4021 Seawater Elements

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
Membrane Preservative Cartridge for Preserving the System and Membrane During Extended Periods of Non-Operation.
655139-03 Oil Adsorbing 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

Benefits of DOW FilmTec Marine RO Membranes:

  • Convert seawater into drinking water on yachts, boats, cruise ships, off-shore platforms, and resorts
  • High flux reduces energy use or pressure required
  • Good rejection results in good quality water
  • FilmTec performance and quality

Common Applications for FilmTec SW30-4021 Seawater RO Elements:

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

Physical Dimensions of DOW FilmTec SW30-4021 SWRO

Dimensions of FilmTec Membrane Element  
A 21.0 (533)
B 1.05 (26.7)
C 0.75 (19)
D 3.9 (99)

SW30-4021 Fits nominal 4-Inch ID pressure vessels.

For more information, please visit this products webpage.