1) Low disturbance: During sampling, the sample tube is inserted into the sediment in a low disturbance manner to obtain sediment samples with distinct layers and material composition.

2) Pressure maintenance and replenishment: After the sampling is completed and the sample cylinder is transferred to the pressure maintenance cylinder, the upper and lower ends of the cylinder are sealed to meet the pressure maintenance requirements of the sample; During the process of lifting the pressure retaining cylinder from the seabed to the ship, under the increasing pressure difference between the inside and outside, the cylinder undergoes volume expansion due to elastic deformation, making it difficult for the sampler to achieve the expected pressure retaining effect. In order to meet the pressure holding requirements of the design, pressure compensation must be performed on the sampler.

3) Insulation: When collecting temperature sensitive sediments such as natural gas hydrates, the in-situ temperature must be maintained.

4) Pollution free: For marine scientific research such as microbiology, it is necessary to prevent the introduction of external pollution throughout the entire sampling process.

5) Non pressure drop post-processing: For many marine scientific studies such as geophysics and geochemistry, it is necessary to conduct non pressure drop analysis on sediments after they are lifted onto ships.

Sediment samplerThe manufacturer will provide a detailed analysis of low disturbance technology as follows:

In order to achieve low disturbance sampling of sediments, various fidelity samplers mainly adopt the following technical measures.

1. Double layer or multi-layer cylinder structure: When collecting harder samples, the outer cylinder with a drill bit is kept at a certain distance from the sample cylinder in the diameter direction to prevent the drill bit from disturbing the inner sample during drilling. This measure is used for PCS, HRC, and FPC.

2. Smooth and intact sample tube: Choose an organic glass tube as the sample tube, with a smooth and intact inner wall to reduce friction with sediment samples and minimize sample disturbance.

3. Special blade design: When collecting soft viscous deep-sea sediments, special blade designs such as small area ratio, small inner diameter ratio, small outer diameter ratio, and adding a thin-walled cylinder in front of the blade are used to control the plastic deformation zone of the sample and reduce sample disturbance.

4. Claw spring extension mechanism: The claw spring at the lower end of the sampling cylinder will damage the structure of the sample. During sampling, the claw spring supports the mechanism and opens the claw spring, allowing the sediment sample to smoothly enter the sample cylinder without boundary disturbance; After the sampling is completed, the claw spring disengages from the supporting mechanism and closes, supporting the sediment sample to prevent the collapse of softer sediment and reduce sediment disturbance.

5. Piston structure: For tubular samplers without a piston structure, the frictional force between the sampler and sediment, as well as the self weight of the sediment sample, often cause disturbances such as shortened sample length or bending deformation during sampling. For this purpose, a piston structure can be installed inside the sample cylinder to counteract the frictional force between the sample tube wall and the sample, as well as the sample's own weight.

6. The framework structure of the piston sampler: The piston structure in the piston sampler eliminates the disturbance caused by uneven compaction of the sample, but due to the rebound effect of the ocean current and the lower steel cable connected to the piston, it is difficult for the piston to remain stable at the interface between sediment and water. As a result, the negative pressure above the sample soil column changes, causing the sample to be sucked into the sample cylinder or form a secondary insertion of the sampler for sampling, resulting in sample level disturbance. For this purpose, a frame type base can be used, with steel cables connected to the piston fixed at the top of the frame, with a constant length, to reduce the disturbance caused by ocean currents and lowered steel cables on sample collection. However, this structure is not suitable for long piston samplers.

7. Cable of piston sampler: Nowadays, aromatic nylon fibers are commonly used to replace the piston connecting steel cable in piston samplers. This nylon fiber is a synthetic polymer similar to Kevlar, which has lower elastic elongation (Young's modulus of elasticity 124 GPa) and smaller weight (density 1450 kg · m-3) compared to steel cables. Its almost weightless state in seawater limits the elastic rebound amplitude of the cable, reducing the possibility of the sample being sucked into the sample cylinder or forming a secondary sampling of the sampler.