Miniaturisation of automation technology components is high on the wish list of many customers in the manufacturing industry. But not in the process industry, where the main demand is for pneumatic rotary drives with torque ratings of up to 8800 Nm and weighing as much as 150 kg and more. These specifications are not surprising when we consider that the materials being handled are water, sewage, chemical, liquid and paste media, gases and bulk materials such as sand, gravel and cement.
Festo is highly active in the process industry. Its pneumatic rotary drive, Copar DRD/DRE, is hard at work operating ball valves in many power plants and natural-gas installations and shut-off valves in water and sewage-treatment facilities. In the field of mobile pneumatics, a special version of the Copar has been fitted to over 70 locomotives running on the local railway system of the Argentinian capital, Buenos Aires.
In addition to Festo's proven Copac DLP linear drives, linear actuators for shut-off valves and sluice gates, NAMUR 'Tiger' valves, and Copar rotary actuators, the company has also released its new Sypar DAPS rotary actuators and its DAPZ sensor boxes.
The Sypar DAPS rotary actuator is of Scotch-yoke design for use with 90° valves and is thus a suitable complement to Copar. The Scotch-yoke design allows high breakaway torque to be produced and it can be manufactured easily and at lower cost. The DAPZ sensor boxes expand Festo's existing range of sensor boxes for rotary actuators and offer a wide choice of sensing facilities, connections, design options and areas of application.
Pneumatic actuators are well suited to the process industry for many reasons. They are able to operate under constant load, are maintenance-free for their entire service life and are tolerant of overload. The force and torque generated by a pneumatic actuator can be increased by simply raising the operating pressure, for example, to overcome the higher breakaway resistance of valves resulting from the accumulation of dirt.
Pneumatic drives are equally suitable for use in explosion-hazard areas, whereas electrical drives can be configured for these applications only through complex and costly modifications. In the case of electric-motor drives, in contrast to pneumatics, it is necessary to incorporate monitoring functions such as over-temperature, torque, switching frequencies, service and maintenance intervals into the master control system, which can lead to an enormous number of wired I/O connections. Except for end-position sensing and a compressed-air supply connection, pneumatic actuators require no monitoring or control functions. Pneumatic actuators are thus ideal for keeping up the pressure on production in process automation systems.
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