RAG Rohöl-Aufsuchungs AG

Vienna, Austria

The Future starts Here

[ Published in HOERBIGER@MOTION 01/2013 ]

RAG and HOERBIGER – two companies, which have one key element in common in their business relations: pioneering spirit. RAG Rohöl-Aufsuchungs Aktiengesellschaft, Vienna, Austria, produces natural gas, storing it in natural underground reservoirs. HOERBIGER is considered a specialist for reciprocating compressors and rotary equipment and focuses on innovative products for attractive technological market niches. One of the latest innovations is the HOERBIGER eHydroCOM, an all-electric control system for reciprocating compressors. It supplements the existing HOERBIGER HydroCOM, an electrohydraulic control system which was launched with great success and assures that reciprocating compressors operate reliably and energy-efficiently.

The first reverse flow controls were still pneumatic. In the nineties, the HOERBIGER HydroCOM then focused on a combination of electronics and hydraulics for the continuous capacity control of compressors.

The HOERBIGER stepless capacity control system offers users two key advantages. First, only the amount of gas that is in fact required is compressed. And the controller intervenes where it has the most dynamic and effective impact – directly at the suction valve. HOERBIGER's resource-conserving compression formula is simple: if, for example, 70 percent of compressed gas is to be generated, only 70 percent of electrical energy is invested.

One company that has always trusted in the know-how of HOEBIGER is Austria's RAG Rohöl-Aufsuchungs Aktiengesellschaft. Boasting more than 30 years of experience in natural gas storage, RAG is today one of Europe's leading storage providers. The working gas volume handled by RAG is approximately 5 billion cubic meters, which corresponds to more than half of Austria's annual natural gas demand.

As much as 2.64 billion cubic meters of working gas are stored alone in Haidach, Upper Austria, Central Europe's second largest natural gas storage facility, in an area covering 17.5 square kilometers, at a depth of approximately 1,600 meters – well embedded in sandstone pores and covered by a dense layer of clay marl. Nonetheless, it only takes 60 seconds to deliver the natural gas from the reservoir to the surface. The compressor units play a key role in the delivery process and bring the gas to the necessary injection pressure which is required for further transport in the gas pipelines. The compressor output installed in Haidach is approximately 62 megawatts, which equates to total power of more than 80,000 horsepower.

Another important element in the Haidach production station is the RGV-3 residual gas compressor. It collects the residual gas remaining in the gas fields through boreholes, also referred to as wells, and compresses the gas to a pipeline pressure of approximately 30 bar. Aside from this important role for the operation, the RGV-3 is also special for another reason. It is the first compressor worldwide on which a HOERBIGER eHydroCOM system is installed.

In and of itself, the classic electrohydraulic HydroCOM control system made by HOERBIGER is already an outstanding product: stepless control with every revolution, dynamic response times of a few milliseconds, a strong lifting force of up to 8,000 Newton, a compact footprint of 15 by 25 centimeters, and easy to handle for a service employee.

With the eHydroCOM, HOERBIGER has nonetheless unveiled an advancement – a control system which not only pushes the boundaries of physics, but also offers two particularly customer-friendly unique selling propositions. It is geared toward an extremely broad target market – small compressors with outputs ranging from 400 to 1,000 kilowatt – and it is considerably easier to install than even the electrohydraulic model, HydroCOM. The intelligent combination of two principles on the eHydroCOM actuator has made it possible for the electronics to supply the actuating force necessary to hold the suction valve of the reciprocating compressor open over a defined period. In the practical application, the user therefore no longer needs an auxiliary hydraulic unit. Its oil-free design eliminates all hydraulic components such as filters, feed and return lines, as well as an external cooling unit. Reducing the interfaces has also minimized the risk of faulty connections when maintenance work is performed.

For RAG, as an operator of natural gas storage facilities, the ATEX certification of the new reverse flow control unit played an especially important role in their decision. After all, safety is the top priority for Austria's oldest natural gas exploration and production company. The eHydroCOM actuator has a fully encapsulated housing.


HOERBIGER eHydroCOM is an all-electric control system for the safe and energy-saving operation of reciprocating compressors. As with the proven electrohydraulic HOERBIGER HydroCOM, control with eHydroCOM is stepless: thanks to an innovative actuator, only the amount of gas that is in fact required is compressed, preventing unnecessary energy expenditure. Additional benefits of eHydroCOM include low investment costs and the simple start-up and maintenance of the system, as a result of the elimination of the auxiliary hydraulic unit.


RAG Rohöl-Aufsuchungs Aktiengesellschaft is Austria's oldest exploration and production company. Its core lines are oil and gas exploration and production and gas storage. With a total storage capacity of approximately 5 billion cubic meters, RAG plays an important role in securing the supply in Austria and all of Central Europe.


HOERBIGER offers four major product groups for everything reciprocating compressor-related – compressor valves, rings and packings, control and monitoring systems, and safety technology such as check valves. The company is represented with all these components in the natural gas reservoirs of RAG Rohöl-Aufsuchungs Aktiengesellschaft. Aside from excellent business relations, HOERBIGER and RAG share another common element: promising innovations. The new HOERBIGER eHydroCOM control system is the latest example in this effort.