Two membrane data sheets can show the same nominal permeate flow without describing the same test. A useful comparison keeps every rating attached to its feed solution, applied pressure, temperature, pH, element recovery and active area. This guide uses two verified BOKAWATER catalog records to show the method; it does not declare the models interchangeable or predict site energy use.
1. Read each catalog value as one test package
The BW-8040 record states 10,500 GPD (39.7 m³/d) at 2,000 mg/L NaCl, 225 psi (1.55 MPa), 25 °C, pH 7.5–8.0 and 15% recovery. Its listed active area is 400 ft² (37.2 m²), feed spacer 28 mil, rejection 99.60% and minimum rejection 99.50%. None of those numbers should be detached from the stated laboratory condition.
The ULP-8040MR-2 record also states 10,500 GPD (39.7 m³/d), but at 1,500 mg/L NaCl and 150 psi (1.03 MPa), with the same 25 °C, pH 7.5–8.0 and 15% recovery. Its listed active area is 440 ft² (40.9 m²), spacer 28 mil, rejection 99.60% and minimum 99.50%. Equal catalog flow therefore does not mean equal hydraulic behavior at one common feed and pressure.
2. Recalculate both candidates for the actual duty
Ask for a projection using the same feed analysis, temperature range, permeate quality, recovery target, vessel array, concentrate flow and permeate backpressure for every candidate. Feed salinity changes osmotic pressure; temperature changes water permeability; recovery changes concentration along the vessel. The DuPont manual treats these variables explicitly when normalizing measured flow to a reference condition.
Compare the resulting system pressure, flux distribution, salt passage, pressure drop and cleaning constraints rather than dividing a catalog pressure by a catalog flow. The ULP label and lower stated test pressure are selection clues, not a guaranteed energy saving at site. Pump efficiency, pretreatment losses, piping, controls, number of stages and product backpressure all affect the package energy boundary.
3. Verify mechanical and commercial fit separately
For a new design, confirm pressure-vessel rating, element count, staging, feed-flow limits, minimum concentrate flow and monitoring points. For replacement work, record the exact installed model, element dimensions, permeate-tube details, interconnectors, brine seal direction and vessel hardware. Similar family names or nominal 8040 format do not prove direct compatibility.
Request a proposal table that shows the chosen model, quantity, design software revision, feed analysis date, design temperature cases, recovery, expected initial and end-of-run conditions, and acceptance method. Preserve the manufacturer test certificate with its original conditions. This creates an auditable comparison while keeping catalog performance, engineering projection and contractual guarantee as three different kinds of evidence.
Data to collect before comparing proposals
| Parameter / interface | Unit / format | Why it matters |
|---|---|---|
| Model | BW-8040 | ULP-8040MR-2 |
| Catalog flow | 10,500 GPD (39.7 m³/d) | 10,500 GPD (39.7 m³/d) |
| NaCl test solution | 2,000 mg/L | 1,500 mg/L |
| Applied test pressure | 225 psi (1.55 MPa) | 150 psi (1.03 MPa) |
| Temperature / pH | 25 °C / 7.5–8.0 | 25 °C / 7.5–8.0 |
| Element recovery | 15% | 15% |
| Active area | 400 ft² (37.2 m²) | 440 ft² (40.9 m²) |
| Feed spacer | 28 mil | 28 mil |
| Rejection stated | 99.60%; minimum 99.50% | 99.60%; minimum 99.50% |
Technical references
- DuPont FilmTec — Reverse Osmosis and Nanofiltration Technical Manual ↗Source checked:
Evidence scope — original English record
Defines standard/reference conditions and shows why pressure, salinity, temperature, recovery and osmotic conditions must be normalized when evaluating RO performance.
- DuPont FilmTec — Brackish Water Reverse Osmosis Solutions ↗Source checked:
Evidence scope — original English record
Official comparison page demonstrating that conventional and low-energy membrane families publish flow and rejection under different standard pressures and sometimes different feed conditions.
- Hydranautics — PROC10 Product Data Sheet ↗Source checked:
Evidence scope — original English record
Official example stating test concentration, pressure, temperature, recovery and pH together with specified flow and rejection, and distinguishing normalized test performance from field suitability.
- BOKAWATER — BW-8040 membrane record ↗Source checked:
Evidence scope — original English record
Current BOKAWATER catalog source for the BW-8040 model and its stated test conditions, membrane area, flow and rejection.
- BOKAWATER — ULP-8040MR-2 membrane record ↗Source checked:
Evidence scope — original English record
Current BOKAWATER catalog source for the ULP-8040MR-2 model and its stated test conditions, membrane area, flow and rejection.