28 JULY 2024 WorldWide Drilling Resource® The Denison Core Barrel Adapted from Information by Acker Drill Company The Acker Denison sampler (core barrel) has stood the test of time, providing geologists and geotechnical engineers with consistent, reliable samples from a wide range of materials. The sampler is successful in retrieving intact samples from hard-to-reach areas, such as compacted soil and shale formations, without causing significant disruption to the surrounding environment. Ordinary thin wall samplers are effective in collecting undisturbed samples from clay, silt, and organic deposits, but when hardened deposits require extreme pressure, this sampler does the job with ease. A versatile core barrel, the Denison can be used to collect samples from soft and hard soils by utilizing its double tube swivel design, which helps to prevent undesirable results often caused by high pressure when using thin wall samplers. The unique design allows for easy soil sampling while preserving the structural integrity of the sample, ensuring accurate laboratory results. The innovative design allows the inner tube to precede the cutting bit, preventing torsional disturbance of the sample by the circulating drill fluid. To gather core samples, the Denison core barrel is rotated as it is pressed into the soil, either in a cased hole or a hole stabilized by drilling mud. When a sample is pushed up in the barrel, the fluid or water above it is vented through a disc valve to the low pressure area outside the core barrel, helping to retain the sample with the pressure differential created by the soft materials. Reduced fluid flow helps maintain bit cleanliness and slows the return of cuttings during sampling. The inner tube protrudes below the cutting bit, ensuring precise drilling operations. The purpose of this protrusion is to: j Ensure the sample is recovered from material undisturbed by cutting action of the rotating bit. j Seal off the sample from water or drilling fluid discharged at the face. j Protect the sample from deformation by preventing any rotating drag on the inner barrel. The inner tube remains stationary at all times. Three different sawtooth cutter bit lengths are available for soft, medium, and hard materials sampling, while a cutter bit is recommended for extremely hard and compacted formations. The Denison sampler can be operated by any standard drill rig, and is designed for use with water, drilling mud, or air and has two types of core retainers, a split ring for harder materials and basket spring for soft soils. This type of versatility accounts for the Denison’s worldwide acceptance by soils engineers, foundation designers, contractors, architects, and consultants. ENV 2024 Booth 1503
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