Milestone Compressed Air Technology /Compressors

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Milestone Compressed Air Technology/Compressors A Passion for Pumping Gases

Author / Editor: Ulla Reutner / Dr. Jörg Kempf

The year is 1864 — The Bavarian fairy-tale king Ludwig II ascends the throne. The first pneumatic post dispatch system starts up in Hamburg. Lincoln wins the US presidential elections. And the 28-year old Wilhelm Meyer from Hanover/Germany founds a machine company (Maschinenfabrik) in Aerzen. Of all these things, only the company Aerzener Maschinenfabrik is still a presence today. It has grown. And it has benefited from a pioneering spirit and a richness of ideas, courage and hard work.

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Continuous modernization and expansion have shaped the entire history of Aerzen. In 2008, for example, the company built an efficient new production center that matches the broad diversity of products offered.
Continuous modernization and expansion have shaped the entire history of Aerzen. In 2008, for example, the company built an efficient new production center that matches the broad diversity of products offered.
(Source: Aerzener Maschinenfabrik)

The roots of the machine company, which ultimately evolved into one of Germany's hidden champions, go back even further. In the mid-1850s, Meyer already ran a cement factory in nearby Reher. At the same time, he set up an agricultural machinery factory there in which around 50 workers manufactured steam-powered tractors (traction engines) among other things. The company’s business flourished. The second agricultural machinery factory was built in 1864 in Aerzen.

The location of the new machine company, which was called “Aerzener Maschinenfabrik Adolph Meyer” after Wilhelm Meyer’s father, turned out to be ideal. Here, the company was — and still is — free to grow around the founder’s villa, which still stands today. The first person to run the company was a full-blooded entrepreneur with a sense of technology and open eyes for new business opportunities. In 1867 he brought back the idea of an iron foundry from a trip to England, which was to enable the construction of large machines in Aerzen in the future. While attending the world exhibition in Paris in 1867, Meyer experienced the so-called Roots blower for the first time, which was used to generate the air flow required in portable forges.

From the Agricultural Machinery to Turbo Blowers
Gallery with 8 images

Production of similar blowers was launched just a year later in Aerzen. They were of a simple design — two double-lobe wooden pistons ran in a conveyor housing that was cast using plaster — and could be operated with water power. The company’s own iron foundry, which was previously supplied with air using bellows, profited from this. It was not yet clear that this new “accessory” would soon become the starting point for a long product series that still to this day helps shape the business of Aerzener Maschinenfabrik.

In 1872 Wilhelm Meyer transferred the company Aerzener Maschinenfabrik to his brothers Sigmund and Emil. He appointed civil engineer Heinrich Meier as the factory director, who worked tirelessly to develop and refine agricultural machines and blowers. He obtained twelve patents, including one for rotary piston sealing strips in 1883. The first break in the history of the flourishing factory in the Weser Uplands happened when the company ceased manufacturing agricultural machinery. Instead, sales of blowers to the emerging heavy industry grew, where complete forging plants, pneumatic hammers, blowers etc. were in demand.

Finding a Way Out of the Crisis with Silencers and Turbos

At the start of the 20th century — after Wilhelm Muhlert had assumed management duties — the company ran into economic difficulties. This changed when the then 33-year old engineer Hermann Allstaedt joined the company in 1907. He brought capital into the company, which then traded under the name Aerzener Maschinenfabrik GmbH, and took over the management two years later. This era was the time of big sellers like dust removal systems for residential buildings. The company’s blowers also benefited from its innovative power: for example with silencers, which reduced operating noise levels. Another milestone was when the company started producing turbo blowers in 1911. With the aid of these blowers, it was possible to generate overpressure of up to around 600 hPa. In smelting furnaces and steel mills they were superior to positive displacement (Roots) blowers on account of the increasing daily output and the large amounts of air that were required.

Export business suffered during the First World War. But as a company that was considered important for the war effort and was required to manufacture armaments, the company based in Aerzen still managed to generate profits. The order books continued to be full in the post-war years. Allstaedt considered the rotary piston technology to be a key technology for machine building, which is why he promoted its development and refinement. A new model range with thicker shafts, enclosed wheelhouses and water-cooled side plates was suitable for pressure differences of up to 780 hPa.

The company had to cope with a decline in the 1920s, when competition increased. The company countered this with rotary piston pumps that were capable of pumping high and low-viscosity media. The product portfolio was optimized once again. The range of blowers was divided into medium and high-pressure types. Rolling bearings instead of plain bearings and other improvements delivered a significant increase in rotational speed. However, most importantly, Allstaedt added some vital fresh blood to the company in 1929 in the form of design engineers Karlheinrich Heller and Paul Grote, who brought great skills and competence with them. Nonetheless, it was impossible to escape the effects of the global economic crisis. Many workers had to be dismissed. The company’s own foundry was shut down, and castings would be bought in from external suppliers from then on.

Global Economic Crisis: Specialization Instead of Width

At the same time, Allstaedt decided to specialize production and focus on rotary piston technology. Alongside pumps and blowers, the company added rotary lobe compressors to its portfolio from 1930. After being granted a calibration approval, they quickly developed into a highly successful product.

Anti-Semitism brought about a radical change. The banking house Adolph Meyer, which still owned 50 percent of the company at this point, was expropriated; the shares were transferred via the company Berstorff to Hermann Allstaedt and Karlheinrich Heller, who was now married to Allstaedt’s daughter. In 1941, Allstaedt finally handed over management of the company to his son-in-law. A new technological era began right in the middle of the war: The Aerzen-based company started producing screw compressors for exhaust gases in submarines.

The principle behind this new technology had already been developed in 1879 by Heinrich Krigar. The compressors, which attained higher pressures than positive displacement blowers were produced for the first time by a Swedish company (which later became Svenska Rotor Maskiner) in the 1930s. From 1943 on they were manufactured by Aerzener Maschinenfabrik under license. But this was not enough for Karlheinrich Heller. He planned new screw compressor designs as a building block system that was designed to cover the widest possible range of applications. And it worked. In the post-war period, the screw compressor became one of the company’s most important products.

The economic miracle era brought growth to the entire machine building industry. The aspect that made the Aerzen products more efficient was the fact that, in future, all positive displacement machines would be based on the same components. This meant a radical boost in terms of productivity.

Mining Boom: Ex-proof Positive Displacement Blower

Heller responded to the strong demand in 1953 with the foundation of a subsidiary plant in Hamelin/Germany. Business boomed; every month, the company sold up to 1,000 positive displacement blowers to truck and ship builders. A year later, the company Aerzener Maschinenfabrik had some 464 employees. At the time, one of the most important client industries was mining, where positive displacement blowers were used to extract mine gas. Ex-proof versions ensured that these systems were safe.


When Karlheinrich Heller died unexpectedly in 1960, his wife Anneliese Heller appointed the long-standing engineer Paul Grote as the managing director, as her son Hasso (born in 1935) was still in training. Grote invested further, including in a fourth hall with 4,500 m2 of space. When the company’s 100th anniversary came around in 1964, business was performing outstandingly well. Hasso Heller completed his business administration studies this year and was made assistant to the management. Just one year late Grote died and Heller took over the management of the company together with Friedrich Wessel and Heinrich Rehbein.

The three-man team backed technical innovations, for example oil-free screw compressors for pneumatic transport and compressors with oil injection for refrigeration technology. Increased focus also shifted to internationalization; in 1968 the managers founded Aerzen France as the first foreign subsidiary. At the same time, the global service network was expanded in order to meet the demands of internationally operating plant builders. By the end of the 1960s, Aerzen had a long list of renowned customers on its books, including e.g. Kraftwerk Union (KWU), which required for its nuclear power plants not only positive displacement blowers, but also meticulous documentation. New areas of application were developed with a new series of screw compressors with oil injection for compressed air technology. These increasingly displaced piston compressors as the drive source for pneumatic hammers. Fortunately, road construction was able to offset the decline in sales that resulted from structural changes in mining.

Global Standard with Three-lobe Blowers

The 1970s was a period of expansion for Aerzen. Subsidiaries were opened in London and the Netherlands. With the acquisition of the company Thomas in Emmerthal, competence was built up in the areas of unit construction, container construction and pipeline construction. The company, which had already been manufacturing accessories based on specifications from Aerzen since 1957, was subsequently renamed Emmerthaler Apparatebau GmbH.

Another technical challenge was met with distinction in Aerzen in 1978. The — at the time — biggest positive displacement blower in the world was produced — with a piston diameter of 1.5 m. It pumped 84,000 m3 of process gas per hour. These giant machines were in great demand in steel production for direct reduction plants. This was followed in 1984 by the world’s largest screw compressors for 65,000 m3 of process gas per hour, which went into sodium carbonate production. And in 1987 finally the company shone with three­lobe blowers offering extremely low-pulsation and quiet operation. Current CEO Klaus-Hasso Heller emphasizes: “At the time, this design set a new global standard. A standard that still applies today.”

The new developments were down to new customer markets, for example Nasa and aircraft manufacturers. Sales grew steadily: between 1980 and 1986 from 98 to 140 million D-Marks. 950 people now worked for Aerzener Maschinenfabrik. Hasso Heller invested further, including in CNC-controlled machining centers and an in-house design department with 70 employees. And Aerzen became even more international in its outlook, with subsidiaries in Spain, the USA and South Africa among others. Right from the start, the non-European subsidiaries also manufactured accessory parts and assembled units.

In 1989 the Maschinenfabrik was represented in over 80 countries. In its 125th year of history, Aerzen generated a record turnover of 180 million D-Marks. The company management invested further in modernization and expansion of production, as well as in a quality department. This was the basis for the introduction of a quality management system in 1990, which was audited by Det Norske Veritas. The seal of approval of this renowned company carried great weight with international companies.

One target market that would end up shaping the business of Aerzen all the way to the current day started to gain importance in the 1990s: environmental technology. Tailor-made machines for aeration of sewage treatment plants and for flue gas desulfurization went into this industry. From 1994 onwards the newly developed Delta Blower units were also supplied. These units with three-lobe pistons ran with low pulsations, while an automatic belt tensioning system further reduced maintenance requirements. The new development brought lasting success: Within the space of five years, Aerzen sold 10,000 Delta Blower units.

From the Agricultural Machinery to Turbo Blowers
Gallery with 8 images

Innovations at two-yearly intervals were now the norm. The screw compressor series Delta Screw for oil-free compression of air and neutral gases was presented in 1996. Just one year later the refrigeration compressor Variscrew was launched with a refined rotor profile and durable roller bearing. Just like with the screw compressors, a modular building block approach ensured that the company could manufacture in accordance with individual customer requirements and adapt its products to different purposes — ranging from the meat industry to breweries and process cooling.

Major Challenges at the Turn of the Millennium

Klaus-Hasso Heller head of Aerzener Maschinenfabrik: “Over the course of the last almost 155 years, SME approach was the driving force behind our development, and it will remain it in the future.”
Klaus-Hasso Heller head of Aerzener Maschinenfabrik: “Over the course of the last almost 155 years, SME approach was the driving force behind our development, and it will remain it in the future.”
(Source: Aerzener Maschinenfabrik)

There were changes at the top again in 2000. Hasso Heller handed over the management of the company to his son. Klaus-Hasso Heller (born in 1967) had already taken on an active role as assistant to the management in 1999. The new millennium brought major challenges for the industrial engineer, because the weak economy made life difficult for the machine building industry. He restructured the company’s product range and perfected the modular building block design. The machinery pool was modernized, and another storage hall and an assembly hall were built. This enabled Aerzen to benefit from the recovery in 2004 — swiftly reaching the limits of its capacity again. A major investment of 65 million euros was due, with the money being spent on a production center for screw compressors and blowers with floor space of around 11,000 m2, which was inaugurated in 2008.

In this year, developments picked up speed at international level. Subsidiaries were created in Poland, Hungary, Slovakia, Czech Republic, Romania and Russia. And the company management concentrated more and more on growth markets in Asia, South America and Africa. A production site was built in 2008 in Baroda/India (Vadodara), along with a company building for assembly in Shanghai in 2013. Aerzen founded a first foreign production site for main components in South Korea. They had already worked closely together here with the company KTurbo, developer of a speed-controlled turbo blower with air suspension. This became the nucleus of Aerzen Turbo.

All the way through to the 21st century, ever new generations of machines have demonstrated the unwavering innovation capacity of the company, which presented the fifth generation of Delta Blower compact blower units in 2006, the likewise fifth generation of the Delta Screw in 2008 and, most recently, a new series of water-injected air compressors. In the following years, Aerzen kept going “one better.” For example, in 2018 Aerzen’s G5plus generation of compact turbo units raised the bar by a further ten percentage points in terms of energy efficiency.

Pioneering Developments in Compression

In 2010 Aerzen presented the rotary lobe compressor Delta Hybrid, which was another highlight in compressor engineering. It combines the advantages of screw compressors and positive displacement blowers by using two different rotor profiles to cover low pressure differences up to 800 mbar and higher pressure differences up to 1,500 mbar. “With this, we have developed a completely new approach to compressor design,” says Klaus-Hasso Heller. “It is 15 percent more energy efficient in operation than other compressors, which makes it interesting particularly for energy and cost-sensitive processes like those in sewage treatment plants and cement factories.” As part of this pioneering development, Aerzen filed no fewer than seven patent applications — including for the bearing system, which ensures a record-breaking service life.

Three different model series have been available since for heavily fluctuating process air demands in biological sewage treatment plants: Delta Blower, Delta Hybrid and Turbo Blower, which can be coordinated using the combined Aersmart control system. Performance3 is what Aerzen calls the resulting intelligent coordination between the systems. Since 2017, Aerzen has pushed even further into the solutions business with its offerings Aerwater and Aeraudit. Aeraudit is a service that covers the volume flow measurement for the actual load demand, while Aerwater is a complete solution that intelligently combines machines, electronics and service packages.

But it is not just the innovative products that will secure the future viability and sustainability of the company. In 2011 — soon after the directors Bernd Wöhlken and Björn Irtel joined — the company set out an ambitious program for itself in the form of its “Vision 2022.” Its goal is to make Aerzen one of the three world-leading application specialists in the transportation and compression of gases. The focus is on products and production methods that are energy-efficient and make effective, sparing use of resources. The high quality standards that have always been in place not only for products and solutions, but also in terms of delivery dates and reliability, are being underlined with a quality initiative. Part of the Vision 2022 is also an uncompromising focus on the needs of the customers as the basis for product development.

The creators of Vision 2022 laid the foundations for “Systematic Growth.” This is bearing increasing fruit, for example in the form of the Process Gas Division founded in 2011, the activities of which are defined by the application. In addition, it also provides impetus for further product developments, for example the Alpha Blower series of large blowers in 2017, which features 104 model variants. Aerzen has also prioritized the application in its solutions for the refrigeration industry as well. Today, customers receive complete refrigeration units that are manufactured at a production site in Hungary and are tailored to their individual requirements.

Globalization is pressing ahead at Aerzen. In a company history and timeline of Aerzen, which was prepared to mark the occasion of the company’s 150th anniversary, Klaus-Hasso Heller wrote: “Our headquarters remain our most important site. However, overall our company Aerzener Maschinenfabrik will develop from a company with an international outlook into a group of companies with even stronger inter-cooperation.” The new company slogan “Expect Performance” represents a promise that Aerzen feels obliged to meet. Despite this, Klaus-Hasso Heller assures that, in the future, the company will not completely give up on the SME approach adopted by his predecessors: “Over the course of the last almost 155 years, this was the driving force behind our development, and it will remain it in the future.”

Additional Information
Editorial Statement: That's Why Aerzener Deserves This Milestone

Dr. Jörg Kempf, Editor-in-Chief PROCESS
Dr. Jörg Kempf, Editor-in-Chief PROCESS
( Source: PROCESS )

Aerzen — masters at spotting and taking advantage of opportunities: How do you become the number one in terms of technology? On the occasion of the 150th anniversary in 2014, Klaus-Hasso Heller, who now heads the family-run company in its fourth generation, emphasized that it was never just a matter of competence and experience — it also takes a good portion of luck. What makes the history of the family company different to others is the fact that, even when faced with an existential crisis, Aerzen always found an opportunity and took advantage of that opportunity to refocus what it does. It is precisely this ability to change that was — and still is — one of the key building blocks of the company’s success. PROCESS believes: This deserves the milestone for compressed air technology/compressors.

* The author is a freelancer at PROCESS.