The close relationship between low-speed centrifuges and sedimentation coefficients.

　　 Low-speed centrifuge The accuracy of the sedimentation coefficient directly determines the efficiency of the centrifuge. When operating a centrifuge, the very first thing to check is whether the sedimentation coefficient has been promptly corrected. This assumption holds true only under the following conditions: 1. The concentration of the balancing ions used should not be excessively high; 2. There should be no solvent molecules capable of binding to the macromolecules. However, as we know, the equations used in the calculation of ultracentrifugation in analytical centrifuges are derived based on the assumption that the experimental system consists solely of two components. In reality, though, balancing ions are always present in the samples, and their concentrations typically range from 0.01 to 1.0 mol/L. Meanwhile, the concentration of macromolecules usually falls within the range of 1.0 × 10⁻⁶ to 1.0 × 10⁻⁴ mol/L. Consequently, the concentration of balancing ions often exceeds that of macromolecules by a factor of 10 or even hundreds of times. This complex issue is frequently overlooked because, when the concentration of balancing ions exceeds 0.05 mol/L, no abnormal phenomena have yet been observed. Nevertheless, if the concentration of balancing ions reaches 1.0 mol/L—such as with NaCl—it becomes absolutely necessary to perform corrections.
　　Low-speed centrifuges utilize powerful centrifugal forces to separate and concentrate particles in suspensions that differ in physical properties such as mass, buoyancy, and sedimentation coefficient. They are equipped with brushless, maintenance-free DC motors or AC variable-frequency drives. Refrigerated centrifuges employ a compression refrigeration system for temperature control. By setting parameters such as centrifugal speed, centrifugal force, duration, and temperature through programming, these centrifuges can achieve the centrifugal separation and precipitation of cells and biomacromolecules. Currently, the nitrogen protection commonly used in low-speed centrifuges actually involves merely installing an inlet pipe and an outlet pipe for nitrogen gas on the centrifuge housing. During operation, nitrogen gas is introduced into the internal chamber. However, there is no quantitative control over whether the nitrogen concentration reaches a safe level; thus, the reliability of this nitrogen protection system is quite poor. An improved nitrogen protection system design incorporates an online oxygen detection device and a pressure transmitter sensor to continuously monitor the oxygen concentration within the centrifuge’s internal chamber during operation, enabling precise control and ensuring that the oxygen content remains within a safe range—specifically, keeping the oxygen concentration below the explosion limits of flammable and explosive substances. Low-speed centrifuge In conventional mechanical design, load-bearing components operate within the elastic linear region of the material’s stress-strain curve—i.e., within the range governed by Hooke’s Law. Within this range, when a component is subjected to a force, it undergoes deformation; the greater the applied force, the greater the resulting deformation. However, once the force is removed, the deformation vanishes entirely, because only elastic deformation occurs, with no permanent deformation taking place. Yet in the rotor design for high-speed centrifuges, in order to fully exploit the material’s latent performance, engineers initially began using aluminum alloys outside the Hooke’s Law range—and this practice has continued to the present day.
　　The low-speed centrifuge is driven by a variable-frequency speed-regulating motor, allowing users to set the acceleration and deceleration rates arbitrarily (from 1 to 9 levels). It features 20 programmable operation modes and is equipped with an imported refrigeration unit. The machine includes multiple protective features such as rotor detection, imbalance detection, and a dual-door lock system. This centrifuge employs microcomputer control with digital display and is driven by a brushless DC motor. It can store up to 9 user programs. The acceleration and deceleration times are short, with a minimum acceleration time of ≤10 seconds. It features an electronic door lock, a stainless steel inner chamber, and allows users to modify operating parameters during runtime. A self-diagnostic fault system automatically detects various types of malfunctions—including overspeed, imbalance, and door-lock failure—and displays corresponding fault codes.
　　A low-speed centrifuge utilizes the powerful centrifugal force generated by the high rotational speed of its rotor to accelerate the sedimentation rate of particles in a liquid, thereby separating substances within a sample that have different sedimentation coefficients and buoyant densities. Primarily, it is used to extract desired components from liquid mixtures. By virtue of the differing densities of each substance, as the centrifuge spins at high speed, the denser liquids settle at the bottom while the less dense liquids float on top, thus achieving layering of the liquid and isolating the pure substances I need. Low-speed centrifuges find applications in numerous fields, including pharmaceuticals and chemical engineering. When substances settle in a medium, they are also accompanied by diffusion—a process that is unconditional and absolute. The smaller the particles, the greater the extent of their diffusion. In contrast, sedimentation is conditional and depends on external forces; the heavier the object, the faster it will settle. Since some particles are so tiny that their sedimentation process is difficult to observe, this is why... Low-speed centrifuge 。