Hydranautics is one of the earlier manufacturers to industrialise thin-film composite polyamide membranes and is now part of Nitto Denko. Its elements are installed in large numbers in power, petrochemical and municipal systems. A distinguishing feature is fine model segmentation within a series: the same 8040 format is split into several models by membrane area (365/400/440 ft²) and feed spacer (standard/LD low pressure drop), so the array can be tuned in detail.
For designers, one practical aspect of the Hydranautics naming system is that the three main series, ESPA, CPA and SWC, correspond to ultra-low pressure, high-rejection brackish water and seawater respectively. Element selection therefore starts with the series, then narrows by area and pressure drop, which is far faster than comparing parameters model by model across dozens of models.
Series
| Series | Positioning | Representative models | Typical application |
|---|---|---|---|
| ESPA | Ultra-low pressure brackish water | ESPA1/ESPA2/ESPA2-LD | Drinking water, industrial process water, municipal and industrial wastewater reuse, and polishing after seawater desalination |
| CPA | High-rejection brackish water | CPA2/CPA3/CPA5 MAX/CPA7 MAX | High-purity water for pharmaceutical, power, electronics and semiconductor plants; high-salinity brackish water |
| SWC | Seawater desalination | SWC6/SWC6 MAX/SWC6-LD | Seawater desalination and high-TDS industrial wastewater |
| ESNA | Nanofiltration/loose RO | ESNA1-LF/ESNA1-LF2 | Softening, removal of pesticides and pathogens, removal of organics and colour, nitrate removal |
| LFC | Fouling resistant, low fouling | LFC1/LFC3/LFC3-LD | Wastewater and surface water with high fouling potential |
| SanRO/PWS | Sanitary/small systems | SanRO-HS, SanROCPA3-4 | Pharmaceutical, biotechnology, medical, food and beverage, semiconductor |
The “Typical application” column summarises the use descriptions on Hydranautics product pages (ESPA, CPA, SWC, LFC, ESNA and SanRO on membranes.com). No assessment of price, lead time or relative performance has been added.
Representative models and parameters
The table below lists representative models in 8040 format (365–510 ft² per element) from the library, sorted by area from largest to smallest; this format contains 93 elements in total. The full model list can be filtered by brand in the design tool.
| Model | Membrane area ft² | Stabilised salt rejection | Category |
|---|---|---|---|
| ESPA2 ULTRA | 510 | 99.6% | Brackish water RO |
| ESPA5 ULTRA | 510 | 99.7% | Brackish water RO |
| CPA5 MAX | 440 | 99.7% | Brackish water RO |
| CPA6 MAX | 440 | 99.8% | Brackish water RO |
| CPA7 MAX | 440 | 99.8% | Brackish water RO |
| ESPA2 MAX | 440 | 99.6% | Brackish water RO |
| ESPA2+ | 440 | 99.6% | Brackish water RO |
| ESPA2-LD MAX | 440 | 99.6% | Brackish water RO |
| ESPA4 MAX | 440 | 99.2% | Brackish water RO |
| ESPA5-LD MAX | 440 | 99.7% | Brackish water RO |
| ESPAB MAX | 440 | 99.3% | Brackish water RO |
| SWC4 MAX | 440 | 99.8% | Seawater desalination |
| SWC4B MAX | 440 | 99.8% | Seawater desalination |
| SWC5 MAX | 440 | 99.8% | Seawater desalination |
| SWC6 MAX | 440 | 99.6% | Seawater desalination |
| SWC6 MAX-800 | 440 | 99.8% | Seawater desalination |
| X_ESPA2-LD MAX | 440 | 99.6% | Brackish water RO |
| X_ESPA5-LD MAX | 440 | 99.7% | Brackish water RO |
How to select
- High electricity price, stable water quality: prefer ESPA2-LD. LD denotes a low pressure drop design, suited to long arrays of 6 or more elements, where the pressure drop in the final stage is more controllable.
- Salinity 2000~5000 mg/L: use CPA3/CPA5, with 99.7% rejection, more tolerant of high salinity than ESPA.
- Seawater or high-salinity water: the SWC6 series; recovery 40%~45%, with attention to per-element pressure drop and the upper temperature limit.
- Reuse water or surface water: LFC3-LD, with a fouling resistant surface and low pressure drop, which extends cleaning intervals noticeably.
The official design software is IMSDesign, including a cloud version. Existing .desx/.des designs can be imported directly into this site for cross-brand comparison.
Official contact
| Official website | www.hydranautics.cn |
|---|
The China region is handled by Nitto Denko (China) New Materials; specific contact details follow those published on the official Hydranautics China website.
FAQ
Which country does Hydranautics come from?
Hydranautics is a US brand headquartered in California and now part of Nitto Denko of Japan.
What is the difference between ESPA and CPA?
ESPA is the ultra-low pressure series: it requires lower pressure for the same permeate flow and suits low-salinity water. CPA is the high-rejection brackish water series, with higher rejection and greater salinity tolerance. Above about 2000 mg/L, CPA is usually preferred.
What design software does Hydranautics provide?
IMSDesign, in both desktop and cloud (IMSDesign Cloud) versions, covering RO, NF and UF. Design files are .desx, or .des in older versions.
Can Hydranautics and DuPont elements be interchanged directly?
Elements of the same 8040 size fit the same pressure vessel, but membrane area (365–440 ft²), pressure drop characteristics and temperature correction differ. Direct substitution changes the permeate and concentrate distribution of each element, so the array must be rechecked.
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Built-in parameters for 733 elements from 8 manufacturers, with comparison under identical conditions, design import and export of calculation reports (Excel/PDF/Word).
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