Sandvik’s Hiflex improves compressor designs

Specially formulated for the flapper valves of automotive and stationary air conditioning compressors, the new Sandvik Hiflex™ strip steel makes possible smaller, more efficient compressor designs. It is of particular interest to producers of CO2 compressors using high discharge pressures.
A flapper valve is one of the most important components in an air conditioning system. It is basically a spring made from pre-hardened steel whose function is to regulate the flow of refrigerant gas to and from the compressor through suction and exhaust valves. As such it is subjected to high cyclical loads and impact stresses.
The new Sandvik Hiflex™ stainless strip steel offers increased tensile strength and improved toughness. It has more than 10% greater bending fatigue strength and 25% improvement in impact fatigue resistance when compared with conventional and commonly used flapper valve stainless steels. It enables compressor designers to miniaturise compressors, use thinner valve flaps, increase reliability, or boost compressor efficiency with greater valve lift.
The increase in bending fatigue strength has been made possible through the increased tensile strength of the material. The impact stress resistance has been improved both by the increased tensile strength and by a substantially higher internal damping capacity.
Sandvik Hiflex™ has a bending fatigue strength of ± 120psi and a maximum allowable impact velocity of 12.5 m/s (41 ft/s). It enables designers to reduce the size of valves and compressors by using shorter valve tongues to achieve the same valve lift. In addition the new steel allows increased valve lift in order to reduce pressure drop across the valve and boost compressor efficiency. Thinner valve flaps can reduce mechanical losses. The new steel can equally be used to improve the reliability of existing valves prone to fatigue failures.
Proven in field testing, the fatigue resistant properties of the new steel have improved the reliability of compressor exhaust valves produced by a major, US manufacturer of automotive air conditioning systems.

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