DCT
3:25-cv-02921
Energy Recovery Inc v. Flowserve Corp
Key Events
Complaint
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Energy Recovery, Inc. (Delaware)
- Defendant: Flowserve Corporation (New York)
- Plaintiff’s Counsel: Germer Beaman & Brown PLLC; Workman Nydegger
- Case Identification: 3:25-cv-02921, N.D. Tex., 10/28/2025
- Venue Allegations: Venue is alleged to be proper based on Defendant's regular and established place of business within the Northern District of Texas.
- Core Dispute: Plaintiff alleges that Defendant’s FLEX isobaric energy recovery device infringes a patent related to noise and vibration reduction in pressure exchange devices used in desalination systems.
- Technical Context: The technology concerns high-pressure fluid exchange systems, particularly those used for energy recovery in reverse osmosis desalination, a critical process for producing fresh water.
- Key Procedural History: The complaint alleges that Defendant had knowledge of the asserted patent prior to receiving formal notice, and that Plaintiff provided both oral and written notice of infringement on or around August 2025.
Case Timeline
| Date | Event |
|---|---|
| 2012-04-19 | ’795 Patent Priority Date |
| 2017-07-04 | ’795 Patent Issue Date |
| 2022-10-01 | Accused FLEX Device Offered for Sale (on or before this date) |
| 2024-06-01 | Defendant Opened Manufacturing Facility in Spain |
| 2025-08-01 | Plaintiff Provided Oral Notice of Infringement (on or before this date) |
| 2025-08-28 | Plaintiff Provided Written Notice of Infringement |
| 2025-10-28 | Complaint Filing Date |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 9,695,795 - Pressure Exchange Noise Reduction
Issued July 4, 2017
The Invention Explained
- Problem Addressed: In pressure exchange devices used for applications like desalination, a rotor with ducts moves fluid between high- and low-pressure zones. The sudden pressure changes that occur when a duct transitions between ports create a "hammer effect," generating significant noise, vibration, and stress that can degrade equipment and waste energy (’971 Patent, col. 1:17-24).
- The Patented Solution: The invention introduces grooves on the faces of the stationary end covers that interface with the rotating rotor. These grooves are positioned between a high-pressure seal surface and a low-pressure port, creating a partially restricted flow path. This allows high-pressure fluid in a duct to decompress gradually as it moves into alignment with the low-pressure port, mitigating the abrupt pressure change that causes the hammer effect (’971 Patent, Abstract; col. 1:40-47). Figure 4B of the patent illustrates these high-pressure relief grooves (414) on the feed-water end cover (’971 Patent, Fig. 4B).
- Technical Importance: The technology provides a mechanical solution to reduce noise and vibration in high-pressure fluid systems, which can enhance equipment longevity and improve energy efficiency (’971 Patent, col. 1:21-24).
Key Claims at a Glance
The complaint asserts independent claims 1, 10, 16, and 20 (Compl. ¶39).
- Independent Claim 1: An energy recovery apparatus comprising:
- a rotor with a duct configured to move between a first and second position
- a high pressure input port in a first end cover
- a high pressure output port in a second end cover
- a low pressure output port in the first end cover
- a low pressure input port in the second end cover
- a first high pressure seal surface in the second end cover adjacent the low pressure input port
- a first groove on the outer surface of the second end cover, located between the seal surface and the input port, configured to release pressure
- a second high pressure seal surface in the first end cover adjacent the low pressure output port
- Independent Claim 20: An end cover for an energy recovery apparatus, comprising:
- a low pressure port
- a high pressure seal surface on the end face of the cover, adjacent the low pressure port
- a groove on the end face, between the seal surface and the low pressure port, configured to decrease pressure on the fluid in the duct, where the groove forms a recess on the end face
The complaint also notes infringement of dependent claims 4 and 5 (Compl. ¶43, 44).
III. The Accused Instrumentality
Product Identification
The Flowserve FLEX device, described as an isobaric energy recovery device (Compl. ¶22, Exhibit D).
Functionality and Market Context
- The FLEX device is a pressure exchanger designed for use in desalination systems (Compl. ¶23). The complaint alleges it functions by using a rotor that rotates relative to two stationary end covers to exchange pressure between high-pressure and low-pressure fluid streams (Compl. ¶25-27).
- An illustration from Defendant's materials shows the FLEX device situated between pumps and membranes in a desalination circuit (Compl. ¶23, p. 8).
- The complaint alleges the rotor-facing faces of the device's end covers contain both high- and low-pressure relief grooves that manage the transition of fluid between pressure zones (Compl. ¶29-30). A photograph provided in the complaint identifies these alleged features on the "FLEX's Seawater End Cover" (Compl. ¶29, p. 10).
- The device is advertised and offered for sale in the United States on Defendant’s website (Compl. ¶35).
IV. Analysis of Infringement Allegations
’971 Patent Infringement Allegations (Claim 1)
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a rotor including a duct and configured to move the duct... | The FLEX device contains a rotor with nine ducts that rotates relative to the end covers. | ¶25, 26 | col. 5:4-7 |
| a high pressure input port disposed in a first end cover... | The FLEX's "brine reject end cover" has a high pressure input port that receives high pressure brine. | ¶28 | col. 6:27-33 |
| a high pressure output port disposed in a second end cover... | The FLEX's "seawater end cover" has a high pressure output port from which high pressure seawater exits. | ¶28 | col. 6:39-41 |
| a low pressure output port disposed in the first end cover... | The FLEX's "brine reject end cover" has a low pressure output port from which low pressure brine exits. | ¶28 | col. 6:54-56 |
| a low pressure input port disposed in the second end cover... | The FLEX's "seawater end cover" has a low pressure input port that receives low pressure seawater. | ¶28 | col. 6:39-40 |
| a first high pressure seal surface in the second end cover and adjacent the low pressure input port... | The rotor-facing face of the seawater end cover contains a high pressure seal surface. | ¶29 | col. 6:41-43 |
| a first groove disposed on a first outer surface of the second end cover and between the first high pressure seal surface and the low pressure input port...configured to release pressure... | The seawater end cover contains a "high pressure relief groove between the high pressure seal surface and the low pressure input port." | ¶29 | col. 8:50-56 |
| a second high pressure seal surface in the first end cover and adjacent the low pressure output port. | The brine reject end cover contains a high pressure seal surface, and a groove is located between this surface and the low pressure output port. | ¶30 | col. 6:54-58 |
’971 Patent Infringement Allegations (Claim 20)
| Claim Element (from Independent Claim 20) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| An end cover for an energy recovery apparatus including a rotor... the end cover comprising: a low pressure port; | The FLEX device's seawater end cover has a low pressure input port, as shown in an annotated photograph. | ¶28, 40 | col. 15:2-3 |
| a high pressure seal surface disposed on an end face of the end cover and adjacent the low pressure port... | The seawater end cover has a "High Pressure Seal Surface" located adjacent to the low pressure input port. | ¶29, 40 | col. 16:2-5 |
| a groove disposed on the end face of the end cover and between the high pressure seal surface and the low pressure port, the groove configured for decreasing pressure... | The seawater end cover has a "High Pressure Relief Groove" located between the seal surface and the low pressure port. | ¶29, 40 | col. 16:6-12 |
Identified Points of Contention
- Structural Questions: The infringement theory relies on mapping the claimed "first end cover" and "second end cover" to the accused device's "brine reject end cover" and "seawater end cover" (Compl. ¶27-28). The dispute may focus on whether the specific arrangement of ports and seals on the accused covers corresponds to the functional definitions required by the claims.
- Functional Questions: The complaint alleges the accused "relief grooves" perform the claimed function of decreasing or releasing pressure (Compl. ¶29, 40). A central question may be whether the accused grooves are merely manufacturing artifacts or fluid-directing channels, or if they are, in fact, "configured to" decompress fluid gradually as the rotor moves, which is the core of the patented solution. The evidence presented in the complaint consists of annotated marketing photographs, raising the question of what detailed technical evidence will be presented to substantiate this functional allegation.
V. Key Claim Terms for Construction
The Term: "groove"
Context and Importance: The presence, location, and function of the "groove" are central to all asserted independent claims. The definition of this term will be critical, as infringement hinges on whether the accused "relief groove" (Compl. ¶29) falls within the scope of the claimed term. Practitioners may focus on this term because its physical characteristics are tied to the pressure-releasing function that distinguishes the invention.
Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The specification describes the groove's dimensions as potentially variable along its length to achieve a desired rate of pressure change, suggesting that the term is not limited to a single, uniform shape (e.g., ’971 Patent, col. 2:50-54). The patent also refers to the structure as a "ramp" in some contexts, implying a functional rather than a strictly structural definition (’971 Patent, col. 2:66-67).
- Evidence for a Narrower Interpretation: The patent distinguishes the invention from prior art by its ability to reduce the "hammer effect" via gradual decompression. A defendant may argue that "groove" must be construed to mean a structure that achieves this specific technical result, as opposed to any channel on the end cover surface. The specific embodiments shown in Figures 4B, 5B, 7A, and 8A-D depict particular shapes and profiles that could be argued to limit the scope of the term (’971 Patent, Figs. 4B, 8A).
The Term: "configured to release pressure and decompress high pressure fluid" (from Claim 1)
Context and Importance: This is a functional limitation that defines the purpose of the claimed groove. The infringement analysis will depend on whether the accused groove is proven to perform this exact function.
Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The specification's summary describes the groove's purpose broadly as releasing "a small portion of the fluid before all the fluid reaches the edge" of the port, which reduces noise and energy waste (’971 Patent, col. 1:40-47). This could support an interpretation where any structure that provides a preliminary, partial pressure release meets the limitation.
- Evidence for a Narrower Interpretation: The detailed description discusses achieving a "relatively constant dp/dt" (rate of change of pressure over time) as a desirable outcome (’971 Patent, col. 8:57-59). A defendant may argue that "configured to" implies that the groove must be specifically designed and dimensioned to achieve this controlled, gradual decompression, rather than incidentally allowing some fluid to leak past a seal.
VI. Other Allegations
- Willful Infringement: The complaint alleges that Defendant willfully infringed the ’971 Patent. The basis for this allegation is two-fold: (1) alleged pre-suit knowledge of the patent and its infringement, and (2) continued infringement after receiving actual oral and written notice from Plaintiff on or around August 2025 (Compl. ¶46-48).
VII. Analyst’s Conclusion: Key Questions for the Case
The resolution of this dispute may turn on the following key questions:
- A core issue will be one of structural and functional correspondence: Do the "relief grooves" identified in photographs of the accused Flowserve FLEX device possess the specific location, structure, and pressure-releasing function of the "groove" as required by the patent's claims, or will they be shown to be structurally or functionally distinct?
- A key evidentiary question will be one of technical proof: Beyond the marketing materials cited in the complaint, what empirical evidence (e.g., computational fluid dynamics analysis, high-speed imaging, or physical testing) will be presented to demonstrate how pressure actually changes within the ducts of the accused device as they traverse the alleged grooves?