Hydranautics ESPA-2521 Low-Energy Reverse Osmosis Membrane Element
Hydranautics composite-polyamide spiral-wound elements deliver proven, reliable performance for energy-efficient brackish and municipal water treatment. The ESPA-2521 is manufactured by Hydranautics, a Nitto Group company and a global leader in RO, NF and UF membranes.
📄 Download the Hydranautics Datasheet (PDF)
Performance Specifications
| Specification | Value |
|---|---|
| Manufacturer | Hydranautics (a Nitto Group Company) |
| Series | ESPA |
| Element Size | 2.5" x 21" |
| Configuration | Spiral Wound |
| Membrane Polymer | Composite Polyamide |
| Active Membrane Area | 9.9 ft2 (0.92 m2) |
| Permeate Flow Rate | 350 gpd (1.3 m3/d) |
| Salt / Nominal Rejection | 99.4% |
| Minimum Rejection | 98.0% |
| Shipping Weight | ~4 lbs (boxed) |
| Shipping Dimensions | 4" × 25" × 4" (boxed W × L × D) |
| HS Code (Tariff) | 8421.21.0000 — water filtering/purifying apparatus |
Operating & Limiting Conditions
| Parameter | Limit |
|---|---|
| Maximum Applied Pressure | 300 psig (2.1 MPa) |
| Maximum Operating Temperature | 113 F (45 C) |
| Maximum Feed SDI | 4.0 |
| Free Chlorine Tolerance | < 0.1 ppm |
| pH Range — Operating | 2-10 |
| pH Range — Cleaning | 1-12 |
| Maximum Pressure Drop | 10 psi (0.07 MPa) |
Physical Dimensions
| Dimension | Value |
|---|---|
| Overall Length | 21.0 (533.4) |
| Diameter | 2.4 (61) |
| Permeate Tube | 0.75 (19.1) |
| Fits Pressure Vessel | nominal 2.5-inch I.D. |
Performance based on Hydranautics standard test conditions: 1500 ppm NaCl solution, 150 psi (1.03 MPa) Applied Pressure, 77 F (25 C) Operating Temperature, 10% Permeate Recovery, 6.5 - 7.0 pH Range. Individual element flow may vary ±15%. Reference: official Hydranautics (membranes.com) datasheet.
Typical Applications
- Energy-efficient brackish water RO
- Municipal and commercial drinking water
- Industrial process water
- Low-pressure / cost-sensitive systems
Frequently Asked Questions
What is the Hydranautics ESPA-2521?
A 2.5" x 21" low-energy reverse osmosis membrane element from Hydranautics, producing up to 350 gpd (1.3 m3/d) at 99.4% rejection.
What is the rated flow and rejection?
Up to 350 gpd (1.3 m3/d) at 99.4%, at standard test conditions (1500 ppm NaCl solution, 150 psi (1.03 MPa) Applied Pressure, 77 F (25 C) Operating Temperature, 10% Permeate Recovery, 6.5 - 7.0 pH Range).
What pressure vessel does it fit?
A nominal 2.5-inch I.D. RO pressure vessel.
What is the price of the ESPA-2521?
Contact ForeverPure at 408-969-2688 or sales@foreverpureplace.com for current pricing and availability.
