Flowrox has come up with a new design for big slurry knife gate valves that, it says, eliminates the need for a cylinder tower and repositions two actuator cylinders to each side of the valve.

Knife gate valves are often found in mineral processing plants, tailings and slurry transport, as well as leaching operations.

The traditional actuator’s tower design usually works well with slurry knife gate valves, but only up to a certain size, according to the Finland-based company. “The bigger the DN, the higher will be the valve,” Flowrox says.

“Let us say we need a valve DN 1200,” the company said. “Using the tower design, it means the valve would be extremely high in open position: 5.6 m! Extreme heights also mean a higher centre of gravity. This makes the knife gate valve more difficult to handle, less stable during assembly and harder to access for maintenance. In other words, less safe.”

Flowrox slurry knife gate valves use a different approach for sizes from DN 900 to DN 1500.

The design eliminates the knife gate valve’s cylinder tower and instead repositions two actuator cylinders to each side of the valve, it said. According to the example above, a Flowrox DN 1200 knife gate valve now measures 3.6 m in a fully-open position: two meters less than the tower design.

The reduced height of the valve means the centre of gravity is positioned lower, Flowrox said. This makes the knife gate valve more stable and safer.

“It is not only easier to install, but also requires much less empty room above the valve,” the company said. “All maintenance access points are situated below 2 m from the ground making them easily accessible. Similarly, all other connections can be done on, or from the ground instead of high in the air.

In the case of the tower design, the service work typically needs to be done 3-4 m above the ground, causing a safety risk, requiring additional safety procedures and consuming more time.”

Another change lies in Flowrox’s knife gate valve body.

Conventionally, the valve body is made from two pieces and bolted together, which can lead to leaking and lots of bolting work during maintenance.

Flowrox slurry knife gate valve bodies are entirely cast in one piece, meaning there are no leakage risks through the body. It also results in a simpler and more robust construction, and less parts, which means savings in spare part inventories and maintenance time.

The company concluded: “Flowrox slurry knife gate valves are more compact, easier to install and much more accessible for maintenance. These valves DN 900-DN 1500 can handle pressures from 10 bar and down to 4 bar, depending on the size.”