Variable speed actuation for a large butterfly valve

Electric actuator specialist, AUMA, has supplied leading British valve manufacturer KOSO Kent Introl with an AUMA SEVEN HiMod variable speed actuator and a large GS gearbox.

The AUMA equipment will operate a 48 inch butterfly valve within a flagship new project for Danish utility supplier Hofor that will transfer the Copenhagen district heating system from steam to hot water.



Copenhagen aims to become the world’s first carbon-neutral capital by 2025, and utility company HOFOR owns the district heating scheme, supplying 98% of the heat to Copenhagen’s 562,000 inhabitants.

The DKK 500 million project to develop the district heating system from steam to a more energy-efficient hot water strategy was initiated in the 1990’s and is expected to complete in 2021.

The 48-inch butterfly valve supplied by KOSO Kent Introl is the largest they have supplied and has a Cv of 59,531. It features a profiled vane that dissipates the energy as a valve works across a large pressure drop, reducing the chance of cavitation.

The AUMA SEVEN HiMod, in conjunction with the GS gearbox, delivers a torque of 90,000Nm.

A variable speed (modulating) actuator means, clearly, that the speed of movement of the valve can vary throughout its travel, moving quickly throughout the majority of the cycle and slowing as it closes to reduce wear on the mechanical components. Variable speed also gives the opportunity for a ‘soft’ start, reducing energy usage.

AUMA UK worked closely with KOSO throughout the delivery phase of the project, helping to design a mounting that allowed the 5.5 inch drive shaft of the valve to interface accurately with the AUMA gearbox.

Commenting, Joanne Handley, KOSO Kent Introl Project Engineer, said: “This is the largest butterfly valve we have ever supplied, and we have worked closely with AUMA throughout the project. Their experience of mounting large gearboxes to large valves in particular was very helpful.”