In the early 90s, professor Ingemar Renberg and Hans Hansson began designing a unique corer for soft sediment. The idea sprang from the dissatisfaction of the corers available on the market. There was a lack of corers with high reliability, supporting samples even under the toughest conditions with a precise extrusion mechanisms. Hence, the HTH sediment gravity corer for soft sediment with its unique extrusion mechanism was designed and built.
The HTH gravity corer for unconsolidated surface sediments fulfills the need for sediment coring equipment that is precise, reliable and easy-to-use. It meets the requirements of the most demanding users, where reliability and credibility are key features. All parts are made from either stainless steel or plastics, chosen to avoid sample contamination. Further, the choice of materials is made to avoid equipment corrosion and to assure many years of trouble-free use.
The corer has been designed for use both in summer- and in winter conditions, at sub-freezing temperatures. When used from the ice, the corer will pass thyrough holes made by a standard 15 centimeter auger.
The sediment corer allows water to flow freely through the tube during descent and the closing mechanism is automatic. Penetration into the sediment can be controlled by adding or removing weights from the corer. The tube is made from polycarbonate and the length is 500 mm. The corer is available in two sizes, with a tube diameter (OD/ID) of 70/66 mm or 90/86 mm.
The extruding device gives precision and control when sectioning the sediment. By rotating the lower part of the extruding device 360°, the sediment core is pushed upwards in exact 5 mm increments, 180° gives 2,5 mm thick samples. The lower part of the extruding device can be readily uncoupled from the treaded rod to allow fast, free movement.
The sectioning tray is attached to the top of the tube for scraping sediment into sample containers. While plastic containers are ideal, the tray has a holder to attach plastic sample bags. The tray is made in one piece from polymethylene plastic (POM) and allows easy and solid mounting, free from moving parts.
The piston is made from PE and it is equipped with a rubber disc instead of O-rings to obtain perfect sealing. The piston is buoyant.
The transport case is designed to accommodate all the parts of the sediment corer. The base plate of the extruding device can be attached to the case to allow an ergonomic working position. The case is a NEFAB PlyPak box made of plywood and UV coated both inside and outside. This type of packaging is built to last and the galvanised steel profiles create a very strong design.