The Georg Fischer line of actuators is now complete with the addition of the EA 21 electric actuator. This type combines particularly flexible use based on a modular concept with a high quality standard. The PA 11/PA 21 pneumatic actuators and the EA 11/EA 21 electric actuators form a perfectly balanced system together with the 546 ball valve.
Shut-off valves such as ball or butterfly valves are usually equipped and automated with electric or pneumatic rotary actuators. Georg Fischer recently rounded off its family of pneumatic and electric actuators for ball valves up to DN 50/2” with the market launch of the EA 21 electric actuator. Quality, a long service life and a flexible modular system are the outstanding features of this actuator generation. All types are certified according to international standards such as CE, UL and CSA.
The PA 11 and PA 21 series, which are designed as symmetrical dual-piston actuators, were specifically developed and sized with the above criteria in mind. By basing the structure of these series on the torque of the 546 ball valves, it was possible to reduce the dimensions and weight not only of the actuator but also of the complete valve to an absolute minimum. Owing to the specially adapted spring assembly sizes, it was possible to reconcile maximum torque with a minimal control air volume. The PA 11/PA 21 pneumatic actuators, which are already successfully installed in numerous applications, are characterised by the following features:
- All-plastic housing made of PP-GV, making them very resistant to aggressive influences
- Pre-loaded spring assemblies for high safety, e. g. during maintenance work
- Optional manual override by fitting an adapter
- Optional position feedback with the multifunction module, which also indicates the correct valve position in conjunction with manual operation
- Valve connection flange according to ISO 5211, F04, F05
- Namur interfaces for accessories and pilot valves
The actuators are also optionally available with a stroke limiter for all three functions (FC, FO and DA) for minimum and maximum flow. The control range permits angles up to 45°. A comprehensive range of accessories can also be supplied.
The following principles and considerations formed the basis for the development of the EA 11/EA 21 electric actuators: state-of-the-art technology and an internal function management concept with communication via a separate system bus. This concept guarantees the flexibility and application-oriented modularity of the actuators.
In order to maximise the benefit to cus-tomers, Georg Fischer distributed the actuator functionality. The EA 11 electric actuator is ideal for standard applications, while the EA 21 actuator is tailored to more complex tasks. Numerous additional features can be implemented with optional printed circuit boards installed according to requirements. The following features are available:
- Four limit switch kits (mechanical, inductive, NPN/PNP or Namur)
- Heating element and/or resetting unit similar to those of the EA 11
- Position indicator for a 4…20 mA signal
- Positioner with variable input signals or PID controller with auto-adaptive parameter settings
- Additional PCB for Profibus DP to facilitate digital serial control
The EA 21 also supports status monitoring for the actuating time, number of cycles, current input and actuating time extension. If one of these pre-set values is exceeded, a signal is output. The error message must be reset after the fault has been rectified. These options can be implemented individually or combined as desired.
The EA 11 and EA 21 electric actuators additionally feature an all-plastic housing with IP 65 protection and an IP 67 cable gland. The plastic housing is flame-re- tardant. An emergency manual override is integrated as a standard feature. The actuators are CE, CSA and UL-compliant. All electrical connections can be made via terminals.
Robust gearing forms the central unit onto which a DC motor designed for a long service life is assembled. Mechanical modularity is achieved by installing additional gears. The actuators can be retrofitted for a maximum torque of 200 Nm. The basic version for the 546 ball valve is rated for a maximum torque of 20 Nm.
The standardised connection flange can be used to mount the 546 ball valve or another compatible valve. The standard emergency manual override ensures safety in all situations.