Bitzer SE

Sindelfingen, Germany

HOERBIGER Reed Valves in Refrigeration Applications

[ Published in HOERBIGER@MOTION 01/2011 ]

Whether frozen pizza in the supermarket, freezing tuna at sea, the reliable storage of blood plasma, or the air-conditioning of buildings is at stake–BITZER SE, a leading manufacturer of compressors for refrigeration and air-conditioning systems, ensures the right temperature. HOERBIGER has supplied components to BITZER since 1967. The modest beginnings have evolved into a close working relationship. Today, HOERBIGER supports the company as a system supplier on its global growth track and is involved in the development of innovations.

Artificial refrigeration on demand in the required amount and at the required temperature has become an indispensable feature of modern society. Today, many production and development processes are possible solely with the deliberate use of refrigeration engineering. In most instances, the cooling energy is generated in what is known as a vapor compression process, requiring the use of compressors.

A large portion of these compressors comes from BITZER, one of the global market leaders. The company has been considered a refrigeration and air-conditioning specialist since 1934. In addition to reciprocating compressors, BITZER also manufactures and supplies screw and scroll compressors as well as pressure vessels and condensing units all over the world.

At the Schkeuditz plant, BITZER’s production area covers almost 183,000 square feet. That is where the reciprocating compressors are manufactured. BITZER machines the majority of compressor components in-house–housings, connecting rods, and shafts. An exception is the reed valves, which are key for the efficient operation of the compressor.

The reed valves are supplied by HOERBIGER Kompressortechnik GmbH in Schongau. Housings are available for two-, four-, six- or eight-cylinder compressors. While the two-cylinder compressors are not much larger than a motorcycle engine, the eight-cylinder models are reminiscent of full-blown passenger car engines. Machining operations include gray cast iron and cast aluminum housings. Due to their light weight, compressors featuring aluminum housings are used primarily for buses, trucks or ships. Compressors equipped with gray cast iron housings are generally used in stationary applications such as in supermarket systems, fresh produce cases and refrigerating chambers.

The demands on the reed valves supplied by HOERBIGER are enormous. They must withstand several million load changes, be absolutely leak-proof and virtually wear-free–this is the only way to ensure efficient operation. After all the components are mounted, the compressors still have to pass through a number of tests, such as the high-voltage, leak or strength test. These tests are part of international or BITZER-internal standards and regulations. Only when all examinations and functional tests have been passed and meticulously documented will the compressors receive their final look: several coats of the traditional BITZER green paint.


The valve plates used at BITZER in Schkeuditz are supplied by HOERBIGER Kompressortechnik GmbH in Schongau, Germany. The precision components consist of the machined and ground seat plate with spherically embossed valve seats, the intake, pressure and spring disks made of spring band steel, and the gas-nitrided pressure stroke limiters. The valves are subject to especially high demands because they must function maintenance-free, and virtually wear-free, for millions of cycles. The efficient operation of the compressor is considerably dependent on the valve. This makes it one of the performance-defining components of the compressor. Every year, HOERBIGER delivers approximately 600,000 reed valves to BITZER’s plants around the world.

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BITZER Kühlmaschinenbau GmbH was founded by Martin Bitzer in 1934. Today, the company is owned by Peter Schaufler. BITZER employs over 2,700 people in 32 locations worldwide. It is headquartered in Sindelfingen near Stuttgart, Germany. The Schkeuditz site has been part of BITZER since 1991. BITZER Group is the largest independent manufacturer of coolant compressors worldwide. BITZER is represented globally with sales companies and production sites for reciprocating, screw and scroll compressors, condensing units as well as pressure vessels.


BITZER and HOERBIGER's successful cooperation has existed since 1967. The conceptual planning, design, and production of reed valves are generally carried out in a close development partnership with the customer. This is key for creating a homogeneous compressor-valve unit.