How to set the speed and time for a second-hand bag-type centrifuge, the effectiveness of centrifugal separation is not only related to the type of centrifuge, centrifugal method, centrifugal medium, and density gradient, but also crucial in actual operation are the determination of the centrifuge speed and centrifugal time for the second-hand bag-type centrifuge, as well as conditions such as the pH value and temperature of the centrifugal medium.
Section 1: RPM of Used Centrifugal Decanter Bag Filter
The magnitude of centripetal acceleration depends on the speed of the rotor and the rotational radius of the particles. When describing centrifugal conditions, relative centrifugal force fields are often used as well. In practical work, the data for the centrifugal force field refers to its average value, meaning the centrifugal force field experienced by particles at the point in the centrifugal solution.
Section II: Centrifugal Time
Centrifugation time varies depending on the centrifugation method. For differential centrifugation, it refers to the time it takes for a particular particle to completely settle at the bottom of the centrifuge tube; for isopycnic density gradient centrifugation, it is the time for particles to reach a state of equilibrium at the isopycnic point; and for density gradient centrifugation, it is the time required to form distinct zones. The factors influencing the zone formation time or equilibrium time required for density gradient and isopycnic density gradient centrifugation are complex and can be determined through experimentation.
The settling time of particles, also known as clarification time, refers to the time required for particles to completely settle from the surface of the centrifuged sample liquid to the bottom of the centrifuge tube. The settling time is determined by the settling velocity and distance of the particles.
Section 3: Temperature and pH Value
To prevent the aggregation, denaturation, and inactivation of separated substances, it is essential to not only pay attention to the selection of the centrifugal medium but also to control the temperature and the pH value of the medium solution, among other centrifugal conditions. The centrifugal temperature is generally maintained around 4 degrees Celsius. For enzymes with good thermal stability, centrifugation can also be performed at room temperature. However, during ultra-high or high-speed centrifugation, the high-speed rotation of the rotor generates heat, leading to a temperature increase. Therefore, a refrigeration system must be used to keep the temperature within the specified range.
The pH value of the centrifugal medium solution should be within the pH range where the enzyme is stable; buffer solutions may be used if necessary. Additionally, excessive acidity or alkalinity can cause corrosion to the impeller and other parts of the centrifuge, and should be avoided as much as possible.
