ERI PX Pressure Exchanger Series: PX-140, PX-220, PX-260, PX-300 (PX300), PX-Q300 (PXQ300), PX-400, PX-Q400 — Complete Reference
The Energy Recovery Inc (ERI) PX Pressure Exchanger is the industry-standard isobaric energy recovery device for seawater reverse osmosis. Operating at 97%+ transfer efficiency, the PX series cuts SWRO energy consumption from ~6.5 kWh/m³ to 2.5–3.0 kWh/m³ — a 55-60% reduction in operating cost. This guide covers every PX model, sizing, applications, and how to choose the right unit.
Models covered: PX-140 (PX140), PX-220 (PX220), PX-260 (PX260), PX-300 (PX300), PX-Q300 (PXQ300), PX-400 (PX400), PX-Q400 (PXQ400). Each model is available with same-week dispatch from Denmark or California warehouses.
ForeverPure stocks the full ERI PX line including PX-140, PX-220, PX-260, PX-300, PX-Q300, PX-400, and PX-Q400, with stocked spares and overnight shipping for production-stopping failures.
What Is an ERI PX Pressure Exchanger?
The PX is a rotary positive displacement device that transfers hydraulic pressure directly between two fluid streams without intermediate energy conversion. In an SWRO system, ERI PX captures the high-pressure brine reject (~800 psi, 60% of feed flow) and uses it to pressurize incoming low-pressure feed water. Because the transfer is direct fluid-to-fluid through a rotating ceramic rotor, efficiency exceeds 97% — far higher than the 85-92% typical of pump-based ERDs.
Complete ERI PX Model Reference
| Model | Flow Rate (m³/h) | Flow (GPM) | Typical SWRO System Size | Stock Status |
|---|
| PX-140 | 32 | 141 | 5,000–15,000 GPD | Build to order |
| PX-220 | 50 | 220 | 10,000–25,000 GPD | Stock |
| PX-260 | 59 | 260 | 15,000–35,000 GPD | Stock |
| PX-300 | 68 | 300 | 20,000–50,000 GPD | Stock — most popular |
| PX-Q300 | 68 | 300 | 30,000–80,000 GPD | Stock — quietest, most efficient |
| PX-400 | 91 | 400 | 50,000–100,000 GPD | 2-3 weeks lead |
| PX-Q400 | 91 | 400 | 50,000–120,000 GPD | 4 weeks lead |
How the ERI PX Works (Technical Overview)
Inside the PX housing is a single moving part: a ceramic rotor with axial channels (ducts). The rotor spins at 1,200–1,800 RPM, hydraulically driven by the fluid streams themselves (no motor). Each channel cycles through two pressure zones:
- Pressurization stroke: A duct opens to high-pressure brine, which displaces the low-pressure feed water inside, pressurizing it to ~800 psi
- Discharge stroke: The duct rotates to align with the discharge port; pressurized feed exits to the membrane while new low-pressure feed enters
This cycle repeats thousands of times per minute with no mechanical losses — only the small kinetic energy of the rotor itself.
Why Choose ERI PX Over Other Energy Recovery Methods
| ERD Type | Efficiency | Typical Cost | Maintenance | Best For |
|---|
| ERI PX (isobaric) | 97%+ | $$$ | Low (1 part) | 10,000+ GPD continuous duty |
| FEDCO HPB (turbocharger) | 80-88% | $$ | Moderate | 10,000–500,000 GPD with particulate brine |
| Pelton wheel turbine | 70-78% | $$ | Moderate | Legacy systems |
| Throttle valve (no recovery) | 0% | $ | None | Batch/intermittent only |
For any SWRO system above 10,000 GPD operating more than 12 hours/day, an ERI PX pays back in 12-18 months on energy savings alone.
Applications
- Hotel and resort SWRO — capacity 30,000–200,000 GPD, where energy cost dominates OPEX
- Industrial process water — bottling, food processing, electronics manufacturing
- Municipal desalination — community plants 100,000 GPD to 5 MGD
- Offshore platforms / FPSO — where every kWh costs and weight matters
- Solar-powered SWRO — energy efficiency multiplies the value of every solar watt
Specifications & Datasheets
Each PX model has detailed performance curves, pressure-flow envelopes, and material specs. Request the official ERI datasheet for any model:
Request PX Datasheet & Quote
Frequently Asked Questions
What's the difference between ERI PX and PX-Q models?
PX-Q models (PX-Q300, PX-Q400) are the latest generation with a redesigned rotor that reduces noise by 5-7 dB(A), lowers vibration, and pushes efficiency to 98%+. They cost ~10% more than equivalent standard PX but pay back in lower maintenance and quieter operation. Recommended for hotel/residential adjacent installations.
How much does an ERI PX cost?
ERI PX pricing ranges from approximately $25,000 (PX-140) to $90,000 (PX-Q400). Most commercial installations use PX-220 to PX-Q300, in the $35,000–$65,000 range. ForeverPure quotes per project; request a formal quote with your system specs.
What maintenance does an ERI PX need?
The ERI PX has only one moving part (the ceramic rotor). Routine maintenance is limited to inspecting the rotor every 5 years and replacing the simple seal and end cover assemblies. Total maintenance cost is typically under $500/year for a PX-300 — among the lowest TCO of any SWRO system component.
Get a Quote for Your ERI PX
Tell us your SWRO system capacity, operating hours, and current/planned energy recovery setup. ForeverPure engineers will recommend the correct PX model and provide a formal quote within one business day.
Request ERI PX Quote → · PX-300 Details · PX-Q300 Details · Desalination System Buyer's Guide
