LESER API Type 526 upside down in salt water

One project LESER is currently involved in is the use of wave energy to generate electricity. The Danish company WAVEPISTON (www.wavepiston.dk) has been researching and developing a new way of generating energy from wave power since 2006, the “Competitive wave energy on islands” project. A large-scale plant is under construction off Gran Canaria / PLOCAN. 

In cooperation with our partner ARMATEC LESER supplies a safety valve for this project, which is mounted upside down under water and ensures the safety of the pump.


Wavepiston system illustration 3

Wave power plant off the coast of Gran Canaria / PLOCAN, (C) WAVEPISTON

Skizze Ventil kopfber unter Wasser
Safety valve in upside-down position two meter below the water surface in duplex, (C) WAVEPISTON

What is the challenge of the "Competitive wave energy on islands" project?

LESER is using safety valves for the first time at a depth of two meters below the seawater surface. For this reason, corrosion-resistant duplex materials are used for the components. 

The unusual installation situation is subject to different pressure scenarios generated by wave force. To ensure that the safety relief valve will function correctly in this environment, extensive analyses of the operating conditions were performed to select the appropriate type and nominal size that is sufficiently dimensioned to vent the required mass flow.

How do you ensure the suitability of the system?

In addition to adapting the safety valve for upside-down use, LESER is supporting the testing process of the new pumping system up to series production readiness. Endurance tests are carried out on a research test rig at DTU Copenhagen. Simulated wave motions generate dynamic pressure conditions in the pump system.

The LESER Type 526 1E2 safety relief valve secures the pump system, with dynamically adjusted response pressures from 40 barg to 80 barg controlled by a hydraulic actuator.
Various operating conditions are tested to ensure suitability. A total eight million pumping cycles are planned in 2023, of which around 600,000 have already been carried out.

Forschungsanlage DTU CopenhagenEN 1773 1000 px

Research facility at DTU Copenhagen, (C) WAVEPISTON

SV und Hydraulik in ForschungsanlageEN 1773 1000 px
Safety valve in the research plant with hydraulic actuator unit, (C) WAVEPISTON

What modifications are necessary for the safety valve?

The safety valve plays a decisive role in this test operation. It must be able permanently to set each operating state with the respective dynamically specified operating pressure in a cycle-dependent manner. This resulted in two challenges.

Firstly, the safety valve must undergo eight million opening cycles in 2023 while keeping the opening pressure constant during the opening phase to ensure evaluable results for assessing pump suitability. For this purpose, the disc was slightly modified to avoid the pulsation effects caused by the system.

Secondly, a mechanism had to be developed to allow dynamic adjustment of the set pressure with second-by-second accuracy. In cooperation between WAVEPISTON and LESER corresponding hydraulic actuator has been developed that is capable of dynamically adjusting the set pressure every second.

More on the subject in a few months, when the plant in Gran Canaria/ PLACON is commissioned and the endurance tests in Copenhagen have been continued.