WF system

Water Freeze-Thaw system with heat recovery

for the tests according to EN 12091 as well as EN 1367-6, EN 1237-1, EN 12004-2 or EN 12467, EN 539-2 and similar.


The durability of the building materials and thus of the infrastructure also includes their resistance to freeze-thaw attacks. Frost stress is a dynamic process that is both a transport mechanism and a damage mechanism. In the damage mechanism, a distinction is made between internal damage as a result of microcracks that occur during freezing due to internal stresses in the component, and external damage as a result of surface weathering. Both are related to the degree of saturation of the samples and ice expansion.

The tests of the frost resistance of the numerous building materials are reflected in a large number of standards and test regulations. With more than 25 years of experience in the field of freeze-thaw tests, Schleibinger Geräte GmbH offers various versions of automated freeze-thaw test systems for testing the quality of building materials for their frost resistance in order to sustainably extend the service life of the infrastructure.

The newly developed water-freeze-thaw system (WF system) is used to test the freeze-thaw resistance of samples. In particular, samples of insulating materials can be tested in the WF system facility according to EN 12091. The samples are alternately and automatically stored in water or in the air. The air in the test room can be tempered from -30°C to +60 °C. Three fans built into the cover ensure even air distribution in the test room. Thawing can take place both under water and in the air. The test room can be flooded with tempered water. As a result, a large number of other freeze-thaw tests are possible, e.g. according to EN 1367-6, EN 1237-1, EN 12004-2 or EN 12467 and similar.

With an automatic cycle change of the WF system, tests with freeze-thaw changes can be carried out automatically, which previously could only be carried out manually. With a usable chamber volume of approx. 0.6m x 0.6m x 2.2m, a correspondingly large number of different samples can be tested simultaneously. The system has an internal water tank in which the water is tempered and made available for flooding the test room. To avoid contamination, the water tank is equipped with a UV light-based disinfection device.

The WF system is equipped with a total of four freely placed temperature sensors. In addition to continuous temperature recording, other values such as water levels, flow rates, pump torques, overpressure, underpressure and temperature of the refrigeration system are also monitored and recorded.

If the test profiles differ from those specified in the standard, they can be freely programmed within the system specification, as with all Schleibinger systems. As a result, various variations of freeze-thaw cycles are possible. The operation of the system is thus customer-specific and target-oriented.

The WF system operates with a low-GWP coolant and is equipped with heat recovery. To thaw the samples under water, the water in the storage tank is tempered from the heat recovery of the refrigeration system. During the frosting phase, re-cooling takes place, if necessary, using on-site cooling water or an air-cooled condenser. The system is therefore dynamically aligned to the requirements and the operation of the WF system is therefore significantly more economical and efficient than in comparison to conventional systems of this size.

With the exception of an annual inspection, the WF system is largely maintenance-free. The annual test can be carried out by any certified professional.

The WF system is fully networkable and is controlled with a computer via web browser. The user interface is a web page in a WEB browser, which also allows a graphical representation of the time series. For a continuous process, the WF system is equipped with three independent controllers that are fault-tolerant, highly available and can run any number of processes in parallel. The software is monitored by the software itself. An update can also be carried out during operation.

The space required, including maintenance and service areas, is approx. 6.5m x 3.5m. The required height of the room is approx. 2.4m. The positioning of the individual components can be customized and allows a maximum distance of up to 10 m.



Technical Data

power supply


3 x 400 V/ 32A

max. connection load


ca. 12 KW

usable chamber volume

m (lxdxh)

2.2 x 0.6 x 0.6

space requirement

m (lxdxh)

6.5 x 3.2 x 2.4

min. temperature, air



max. temperature, air