Linear actuators for process control

New integrated positioned linear actuator offers robust, simple and exact process control

Festo has launched an intelligent linear actuator for process automation applications. The DFPI combines the functions of a linear actuator, a positioner and displacement encoder in one, easy-to-install unit. As a result, users can increase operational efficiencies as well as saving time and costs associated with specifying and installing equipment.

The innovative DFPI solution is ideal for controlling knife gate valves and shut-off valves with regulated strokes and for use with all linear-actuated process valves. Typically, linear actuators with externally fitted components are used in these applications. However, these are highly susceptible to mechanical problems and therefore need frequent maintenance.

Now, with this high performance DFPI, process managers can benefit from a more intelligent, robust and simpler solution. It features an all-in-one design whereby all components are fitted inside a compact cylinder housing. Thanks to its sturdy design and high IP65, IP67 and IP69k protection, it is robust and can withstand harsh environments with moisture and dust, providing reliable operation. It also has high corrosion resistance class of CRC3.

DFPI is quick to set up and configure and can be integrated into existing control architecture easily. It can also be controlled easily from Festo’s CPX valve terminal. Thanks to the flow control functions, the back-and-forth movement speed of the piston rods can be set separately or independently of each other and sensing of the intermediate positions is also possible. It gives feedback in a 4-20mA signal about the position of the actuator, which enables the user greater reliability and easier diagnostics.

The DFPI unit is delivered with fittings and connectors pre-assembled, together with the electrical cable and two pneumatic tubes for the power supply and exhaust inside a flexible protective conduit. This saves installation and purchasing time compared with alternative solutions, as only one part needs ordering.

It is available in a wide variety of diameters (100, 125, 160, 200, 250 and 320 mm) and strokes from 40 mm up to 990 mm. Special designs above 990 mm stroke are also available on request.

“At Festo we have a long history and extensive knowledge of technologies for automation in a manufacturing environment. We are now transferring this to the process automation markets, enabling those in industry to benefit from robust, simple, exact process control so they can increase reliability and operate more efficiently,” says Steve Sands, product manager at Festo GB.

“Based on the proven technology of our DLP open / close actuators, this new DFPI actuator with integrated positioner is the most resistant solution available for dust and aggressive environments in the process automation markets. We can now supply both entry level equipment and more advanced positioned actuators, in each case tailored to the customer’s application.”

The DFPI is ideal for regulating knife gate valves in sewage plants, the bulk goods industry and any other applications in which the media in piping systems must be regulated. For instance, in the water and wastewater industry it can be used to control sluice gates for the return sludge at final clarifiers; for the control of pump flow rate in cardboard production in the pulp and paper industry; and for the control of dart valves in many mining applications.