Piston coring devices

Piston corers are sediment core sampling systems used to extract long, undisturbed sediment profiles from fine sediments in standing waters such as lakes or reservoirs. They are operated from a floating platform, a large boat, or from ice. A drilling tower or crane-like mast is usually used as the operating and lifting device. The system is locked before core extraction to prevent the ingress of unwanted sediment and is unlocked via a piston rope or piston rod so that the core tube can move over the fixed piston and pick up the desired sediment segment. The piston creates a vacuum that pulls the sediment core into the core tube in a controlled manner and minimizes compression of the layers. Mechanical or hydraulic core catchers secure the core in the full tube to prevent it from slipping out or breaking off, while drill bits with a smaller diameter than the core tube enable the sediment to be penetrated with as little friction as possible. Piston drilling rigs can typically be used in water depths of approximately 5 to 300 m and, depending on the sediment and operating conditions, enable core lengths of up to approximately 50 m with a core retention rate of up to 95% (e.g., through overlap drilling).