RO membrane cross reference: how a replacement element is actually selected
No single Chinese element answers that question from the model code alone, and a supplier who names one on the strength of a code is guessing. RO membrane cross reference works in one direction: an installed designation tells a sourcing desk the nominal format and the duty class the plant was built around, narrowing hundreds of elements to a few candidate families. Which candidate is right is settled by your feedwater analysis, recovery target, cleaning regime and acceptance criteria - seven data points, none of which appear in a cross-reference table.
MembraLink does not assert that any element it sources is equivalent to, or a drop-in replacement for, any named third-party model. Selection is made against your feedwater analysis, installed format, operating conditions and acceptance criteria, and is confirmed with the manufacturer before quotation.
What an RO membrane cross reference can tell you - and what it cannot
An index of installed models is a starting point, not an answer. From a designation it reports three things dependably: the nominal element format, the duty class the brand owner published it under, and whether the code is a current designation, a family name or a legacy code. That narrows a catalogue to a handful of candidates worth pricing.
What it cannot report is which candidate will hold your permeate requirement, at your recovery, on your feed. Equivalence cannot be established from a datasheet alone; a nominally similar element can still be wrong for the feedwater, vessel, recovery target or cleaning regime. Two elements published under one duty class behave differently in the same vessel because the plant, not the element, sets the operating envelope - the practical consequence of how a thin-film composite element separates water from dissolved salts.
Reading the model code: format, duty class and suffix conventions across makers
There is no cross-industry standard for how to read an RO membrane model number; each brand owner uses its own scheme, and the schemes only look alike. Three parts carry meaning: a letter prefix for chemistry and duty, a numeric block for element size in that maker's own convention, and suffixes covering feed-spacer construction or sanitary variants.
Prefixes hold most of the information. In the FilmTec scheme, XLE and LE mark low-energy brackish duty, BW30 brackish water, SW30 seawater and FR a fouling-resistant construction. In the Hydranautics scheme, ESPA marks energy-saving polyamide, CPA composite polyamide, SWC seawater composite, LFC low-fouling composite, and the -LD suffix denotes an LD construction within that maker's portfolio. Toray reads differently again, with TMG20D-400 listed for low-pressure brackish-water duty in its current RO portfolio. Numeric blocks must be read through the relevant maker's nomenclature: DuPont states that the area number in its eight-inch FilmTec names represents active area, but that convention cannot be transferred to another maker. An unfamiliar suffix is therefore a question for the brand owner, not something to interpret by analogy.
The four duty classes buyers search under, and what each is really asking about
An 8040 replacement enquiry can be screened into four duty questions. A low-energy brackish request needs an energy and pressure review; a high-rejection brackish request needs the downstream permeate limit. A request framed around BW30FR-400 should trigger questions about pretreatment, foulant history and cleaning interval. A request framed around an ESPA4 element should identify the exact installed variant, available pressure and permeate limit before any candidate family is discussed.
An SWRO membrane cross reference enquiry carries an extra variable: boron and the pass configuration have to be resolved before a family can be shortlisted, which is handled in our guide to Gulf SWRO membrane sourcing, boron and two-pass configuration. The families we screen against these four classes are on the 8040 membrane series page.
This index uses four installed-model references to show how an enquiry is framed. It is not an equivalence table: it names no substitute product and publishes no comparative specifications. What we return is the technical data required to scope a replacement against your plant.
| Installed model designation | Brand owner | Duty class, in the brand owner's own qualitative terms | Nominal element format | Catalogue status | What we need from you to scope a replacement |
|---|---|---|---|---|---|
| FilmTec XLE-440 | DuPont / FilmTec | Low energy, brackish water | 8-inch × 40-inch (8040) | Shown in DuPont's public BWRO portfolio reviewed 24 August 2026; confirm the current orderable code against the manufacturer quotation | Available feed pressure; dated feed analysis; recovery target |
| Hydranautics ESPA4 series (ESPA4-LD / ESPA4 MAX) | Hydranautics | Very low energy, brackish water | 8-inch × 40-inch (8040) | Current series and element-level variants shown on Hydranautics' official ESPA page, reviewed 24 August 2026; confirm the orderable code against the current manufacturer quotation | Element-level code on the wrap; permeate limit; recovery target |
| FilmTec BW30FR-400 (also listed as BW30FR-400/34 and /34i) | DuPont / FilmTec | Fouling resistant, wide feed spacer | 8-inch × 40-inch (8040) | Legacy installed designation not shown in the DuPont BWRO portfolio reviewed 24 August 2026; current supply status must be confirmed directly with the brand owner | Cleaning frequency and chemistry; pretreatment installed; foulant history |
| FilmTec SW30HRLE-400 | DuPont / FilmTec | Seawater, high rejection, low energy | 8-inch × 40-inch (8040) | Current product data sheet reviewed 24 August 2026; confirm the current orderable code and revision against the manufacturer quotation | Project permeate boron limit; feed salinity and temperature; pass arrangement |
All third-party brand and model names are the property of their respective owners. They are referenced here solely to describe physical format and duty class for compatibility and replacement-selection purposes. MembraLink is not affiliated with, endorsed by or an agent of any of these manufacturers.
No performance figures are published on this page. Active area, salt rejection, permeate flow, operating pressure and boron rejection are issued only from the manufacturer's own datasheet, quoted with the manufacturer's stated test conditions, and confirmed per procurement against those conditions.
Why an installed code still needs a current brand-owner check
Replacement enquiries often begin with the wrap in the plant room. That is useful evidence of what is installed, but it is not evidence that the same code is orderable today. The official portfolio pages reviewed on 24 August 2026 show both series names and element-level variants, while some installed FilmTec designations do not appear in the current product family list.
A family name can leave the element size or variant unresolved. A code absent from a current public portfolio may be legacy, region-specific or simply omitted from that page. MembraLink does not infer which explanation applies. We record the installed code, check the current brand-owner page, and require written confirmation of the exact orderable designation before using it as a reference point.
The seven data points that decide a replacement - none of which appear in a cross-reference table
These are the data points we need before anything is scoped. A factory will confirm dimensions and its own published test conditions in writing; none will underwrite a permeate outcome in a plant it has not seen.
- Installed format and vessel detail - vessel make and length, elements per vessel, end-cap and adapter arrangement. Fit is confirmed against your vessel drawing.
- A dated, complete feedwater analysis, with the laboratory named. A three-year-old well-field analysis is a hypothesis.
- Design and operating envelope - design recovery, feed temperature range, flux basis, available feed pressure, array configuration.
- The permeate requirement the plant is held to, and by whom: a downstream process, a discharge consent or a tender specification.
- Pretreatment as actually installed, with its current performance record rather than its design intent, and any fouling-index history.
- Cleaning regime - frequency, chemistry, and how the interval has moved over the last two replacement cycles. Usually the most informative record a plant holds.
- Commercial and acceptance frame - annual volume, delivery port, required-by date, and the written acceptance criteria your goods-in engineer will apply.
Actual operating results depend on feedwater quality and system design; the project technical specification governs.
How MembraLink shortlists a Chinese element against your feedwater and your installed format
Our cross-reference process starts from your installed format and duty class, not from a claimed equivalence: we specify against your feedwater analysis rather than against a competitor's datasheet. In sequence - the installed code is resolved to a format and duty class; the seven data points are collected and gaps recorded; candidate Chinese manufacturers are screened against that duty and your acceptance criteria; the manufacturer's own datasheet is obtained with its stated test conditions; dimensional fit is confirmed against your vessel drawing. Active area, rejection and operating pressure are confirmed per procurement against the manufacturer's stated test conditions before any quotation is issued.
The shortlist is compared against your requirement list rather than ranked; the awarding decision stays with you, and every line is marked verified or pending. The factory and document checks behind each candidate are the twenty points in our checklist for qualifying a Chinese RO membrane manufacturer, and each item is recorded through the qualification-file method. EPC teams can apply the same evidence gates through the project-sourcing route.
What a replacement enquiry should contain, and where to send it
A workable enquiry is short. Give the designation printed on the wrap, the annual replacement volume, recovery, feed temperature range, available feed pressure and the permeate requirement, plus the vessel arrangement, delivery port and the date you are held to; attach the most recent feed analysis and any cleaning log. Cross-reference enquiry: tell us the installed model and duty, and we return the technical data required to shortlist Chinese manufacturers. When the file is ready, send your requirement to the sourcing desk.
Sources and verification notes
Brand-family descriptions and model status were checked against the pages below on 24 August 2026. A public web page is not a procurement confirmation. The current manufacturer quotation, datasheet revision, exact orderable code and project test conditions still control.
- DuPont FilmTec RO and NF Technical Manual, revision 19, February 2026: FilmTec nomenclature, duty prefixes and eight-inch element naming.
- DuPont brackish-water RO portfolio: current public BWRO families and published test-condition context.
- DuPont FilmTec SW30HRLE-400 product data sheet, revision 8, January 2026: model designation, format and manufacturer-stated test conditions.
- Hydranautics ESPA product family and Hydranautics SWC product family: current public variants and LD descriptions.
- Toray RO product portfolio: current public brackish-water, seawater and low-fouling designations.