WF system

The Water-Frost-Thaw System (WF System) from Schleibinger is a state-of-the-art, fully automatic test chamber specifically designed to determine the frost-thaw resistance of construction materials. It simulates dynamic frost-thaw processes and thus supports quality assurance as well as the extension of infrastructure service life. With over 25 years of manufacturer experience, the system offers reproducible, standards-compliant testing under realistic conditions for construction companies, testing laboratories, research institutions, and building materials manufacturers.

Functional Principle and Benefits

The WF System automatically switches between air and water media: Freezing takes place in cold air down to –30 °C, thawing under water or in air up to +60 °C, with precise, automatic flooding of the test chamber via a temperature-controlled storage tank. Three integrated fans ensure homogeneous air distribution, while four freely positionable temperature sensors (median value control) and continuous monitoring of fill levels, flow rates, pump torques, and refrigeration unit pressures guarantee the highest accuracy and reproducibility. Freely programmable test cycles allow customer-specific adaptations beyond standardized norm profiles.

Energy efficiency is enhanced by innovative heat recovery (e.g., tempering of thaw water from the refrigeration unit), a refrigerant with low global warming potential, and flexible cooldown via mains water or air-cooled condenser.

Standards

• DIN EN 12091: Frost-thaw resistance of insulation materials.
• DIN EN 1367-6: Resistance of aggregates to frost-thaw cycles with NaCl.
• DIN EN 12371:2010: Determination of freeze-thaw resistance of natural stone.
• CEN/TS 12390-9 / DAfStb Heft 422: Frost-salt testing (cube method).
• ÖNORM B 3303: Test methods for concrete (frost-salt resistance).
• DIN EN 772-22: Determination of frost-thaw resistance of concrete masonry units.
• DIN EN ISO 10545-12: Determination of frost resistance of ceramic tiles and slabs.
• Additionally: ASTM C666 Procedure B, EN 1237-1, EN 12004-2, EN 12467, EN 490/491, EN 539-2, and similar standards.

Technical Data

• Air temperature range: –30 °C to +40 °C
• Empty cooldown rate: approx. –3 K/min (from +20 °C to –20 °C)
• Empty heat-up rate: better than +3 K/min
• Automatic flooding of the test chamber
• Usable volume: approx. 1150 l (floodable ≈ 900 l)
• Control via median value from four freely positionable temperature sensors (A–D)
• UV disinfection of storage tank water
• Stainless steel corrugated tube sensors, waterproof welded
• Cable entry (Icotek system, 60 × 35 mm, splittable)

Special Features for DIN EN 12091

• Sample coverage ≥ 5 cm during thawing phase
• Spacers between samples
• Flat hold-down devices
• Automatic de-icing of hold-down devices before flooding to avoid indentations from ice lenses
• Compressed air drying of hold-down devices to remove residual water

Installation Requirements

• Chamber: W × D × H = 256 × 119 × 143 cm, space requirement 2.5 × 3.6 m
• Refrigeration unit incl. control cabinet: 200 × 183 × 232 cm, space requirement 3.1 × 3.2 m
• Overall system: approx. 6.7 × 3.2 m room area required
• Cooling capacity: 12 kW (tcond = 20 °C, tverd = –30 °C)
• Electrical connection: 3 × 400 V / 32 A