Whether rotary or linear – with ARCA’s pneumatic, electric, and hydraulic valve actuators you always have the right solution on hand. ARCA’s comprehensive product catalogue offers a choice of valve actuators ranging from low to very high actuating forces and torques. If requested, we can also develop and manufacture actuators that are optimised for safety-oriented tasks or have extremely short actuating times. Low lifecycle costs are a feature shared by all our actuators.


Pneumatic Diaphragm Actuators
The simple design of our pneumatic diaphragm actuators with a robust power diaphragm makes them universal in application and also ensures hysteresis-free control across the entire actuating range. These pneumatic valve actuators can be opened or closed using spring force or control air – an option that can be switched at any time.

The integrated adjusting spring ensures that the pneumatic control actuator always assumes a defined limit position. This is accomplished with very short actuating times meaning that alongside their control tasks, ARCA diaphragm actuators also play a key role in safeguarding the plant. The pneumatic diaphragm actuators can also be configured for manual emergency intervention if requested.


Electric Actuators
Actuating and control forces are transferred to the valve using geared motors to ensure that the forces are always available on demand. Suitable ratios guarantee that even extremely high actuating forces are transferred safely and reliably.

Electric actuators are normally operated manually, and can be switched off via configurable torque or travel limit switches. A standardized interface allows the actuators to be used for all common applications.


Hydraulic Actuators
These are characterized by their high actuating forces and speeds. Because of the double piping for the inflow and outflow of media, hydraulic actuators are only specified for technical applications that require them.

 

The classic design: analogue positioner type 824

Positioner type 824 functions according to the tried-and-tested force-balance principle. The pneumatic setpoint standardized signal issued by a pneumatic controller or I/p converter module generates a force on the diaphragm that is balanced with the spring force on the feedback shaft. The resulting difference in force moves the gate valve, which connects the actuator with the intake air or atmosphere, thereby controlling the movement of the valve.


The intelligent design: ARCAPRO® digital positioner type 827A

ARCAPRO® is an intelligent, second-generation positioner. It not only offers a wider range of functions and higher level of reliability, but also features an advanced online diagnostics system and optional maintenance display. The position of the stem is sent to a potentiometer whose output signal is then compared with the setpoint by the microprocessor. Using a special control algorithm, the controller activates the two piezo valves, which connect the actuator with the intake air or atmosphere.
The ARCAPRO® positioner can be operated locally or from the control room.
 

High-performance valve actuator:
Whether you want to use it for control or protective functions, the valve actuator for ARCA’s steam-conditioning valves is designed with your plant in mind. This is made possible by our wide range of pneumatic, electric, and hydraulic actuators. The valve-closing force of all actuators is proportioned according to your requirements.


Multi-functional positioner:
The ARCAPRO® digital positioner provides the steam-conditioning valves with a multi-functional interface to the controller or process control system. It is connected to the actuator directly or using the NAMUR mounting method and ensures that the stroke can always be realized free from backlash for the highest degree of precision. Standardized signals are supported from 4 to 20 mA. HART, Profibus, and Foundation fieldbus standards can also be used to establish a digital interface with bi-directional data exchange (including status messages). This means that the positioner can be parameterised on site as well as remotely via the communication system. Optional accessories such as boosters, limit switches, and solenoid valves are available to customize the valve to suit your individual requirements.

Statically and dynamically leak-proof:
We choose a dynamic stem seal and static bonnet seal in the force bypass that are completely suited to the pressure and temperature range of your application. The surface finish of the stem and the packing material are also factored into this decision. The chambered design normally used for the bonnet seal prevents assembly errors during servicing and maintenance. A self-sealing pinch cap is used for high-pressure applications to ensure that the valve remains sealed regardless of the tightening torque applied to the bonnet screws. These design features also ensure that the valve seat and control cone are not subjected to any lateral forces, thereby minimizing internal leakage as well.

Versatile valve trims:
These are the most crucial functional elements for controlling pressure and temperature. Perforated throttle bodies are designed and manufactured to suit the prevailing flow conditions and the rangeability required. The type of water-injection selected is suited to the temperature of the steam and cooling water. For applications with increased safety regulations, a dirt strainer is inserted at the opening of the steam inlet. This prevents contaminant entry and protects against defects. The patented clamping seat ensures that maintenance is fast, simple, and cost-effective and does not require special tools.