Isobaric energy recovery devices (ERDs) are developing rapidly and playing a significant role in reducing specific energy consumption (SEC) of seawater reverse osmosis (SWRO) desalination systems. However, leakage, abrasion and large pressure loss are still big challenges and remain big problems unsolved among the present ERDs. In this paper, a novel isobaric ERD based on so-called fully-rotary valves (FRVs) is developed to resolve these problems. The key fully-rotary valve energy recovery device (FRV-ERD) consists of only two FRVs and pipelines. The performance of the FRV-ERD is tested by means of an ERD performance test system. The hydraulic performance of the device is tested under laboratory conditions with the test pressure about 3.0 MPa. Experiments show that the operation of the FRV-ERD is stable and the pressure fluctuations of high pressure streams are small. The leakage is not detected and therefore excellent seal performance is proved through tests as well. The measured pressure loss is low and the energy recovery efficiency is as high as 98.47% which is among the best of the reported values. (C) 2016 Elsevier B.V. All rights reserved.