What is Centrifuge: Definition and 78 Discussions

A centrifuge is a device that uses centrifugal force to separate various components of a fluid. This is achieved by spinning the fluid at high speed within a container, thereby separating fluids of different densities (e.g. cream from milk) or liquids from solids. It works by causing denser substances and particles to move outward in the radial direction. At the same time, objects that are less dense are displaced and move to the centre. In a laboratory centrifuge that uses sample tubes, the radial acceleration causes denser particles to settle to the bottom of the tube, while low-density substances rise to the top. A centrifuge can be a very effective filter that separates contaminants from the main body of fluid.
Industrial scale centrifuges are commonly used in manufacturing and waste processing to sediment suspended solids, or to separate immiscible liquids. An example is the cream separator found in dairies. Very high speed centrifuges and ultracentrifuges able to provide very high accelerations can separate fine particles down to the nano-scale, and molecules of different masses. Large centrifuges are used to simulate high gravity or acceleration environments (for example, high-G training for test pilots). Medium-sized centrifuges are used in washing machines and at some swimming pools to draw water out of fabrics. Gas centrifuges are used for isotope separation, such as to enrich nuclear fuel for fissile isotopes.

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  1. D

    I G-force centrifuge mounted on opposite rotating platform

    Query - does a centrifuge spinning to create X g-force, mounted on a platform that is rotating the the same rpm's the opposite direction, negate the g-force? Or does the g-force stay the same but from an outside perspective the centrifuge appears stationary?
  2. nomadreid

    Medical Is a small tidal force on the body harmful over the long term?

    In the following page (which, despite examining a question that comes up in science fiction, raises valid scientific questions): http://pages.erau.edu/~andrewsa/sci_fi_projects_spring_2015/Project_1/Eilts_Mitchell/Enders%20Game%20Eilts/Enders%20Game%20Eilts/index_Eilts.html I encountered the...
  3. N

    Solute separation by centrifuge

    My view is that it is possible to separate any solute from any solvent by centrifuge. Likewise it is possible to separate heavy water from H1 water by centrifuge. Molecular disassociation is probably a borderline possibility, especially if we consider the molecular disassociation of your...
  4. Lukeblackhill

    I Separation of Fluids in a Centrifuge

    Morning Mates, I have a question based in a statement take from Berkeley Physics Course, Vol.1 - Mechanics, pg. 102-103, where it reads, "Suspended molecules whose density (mass/volume) is different from that of the surrounding liquid will experience in the ultracentrifuge cell a strong force...
  5. caters

    Artificial gravity on a ship without the whole ship rotating

    I know that rotation can cause there to be artificial gravity. But I was thinking of making a floor plan that is all horizontal with the generation ship having a rocket shape and with it being longer than it is wide and wider than it is tall. So I was thinking of giant centrifuges on every...
  6. karush

    MHB 9.25 a centrifuge takes up only 0.127 m of bench space

    $\textsf{An advertisement claims that a centrifuge takes up only $0.127 m$ of bench space}$ $\textsf{but can produce a radial acceleration of $4100 \, g$ at $6830 \, rev/min$}$ $\textsf{a. Calculate the requested radius of the centrifuge}$ OK the only thing I can guess here is...
  7. G

    ZnO nanoparticles do not sediment properly in centrifuge?

    I centrifuged my sample at 9000 rpm for 30 minutes. There is a layer of sediment on the wall but if i tilt the centrifuge it comes off the wall.
  8. Gotbread

    Using a centrifuge to extract heavy water (help with the calculations please)

    Hello everyone! I have seen several DIY projects which successfully gathered heavy water from normal water. For example Cody from codys lab used electrolysis to "enrich" the water. This however is a messy process. So i became curious, if this can be done easier by centrifugation. Based on...
  9. artriant

    Falling apple inside a space centrifuge

    When a mass is in a circular motion and suddenly gets released by its centripetal force, it will continue traveling in a straight path (tangent to the circle and perpendicular to the radius in the moment of release) if no other forces acting. So let’s make a case: We have a space centrifuge...
  10. B

    Calculating the Frequency of a Centrifuge in Hertz and Revolutions per Minute

    Homework Statement A research apparatus called a centrifuge undergoes a centripetal acceleration with a magnitude of 3.3x10^6m/s^2. The centrifuge has a radius of 8.4cm. Calculate the frequency of the centrifuge in hertz and in revolutions per minute. Ac=3.3x10^6,/s^2 r=0.084m Homework...
  11. Vorrawit

    System analysis of a centrifuge

    Homework Statement Initial training involves a slow onset rate (1 g/s) run up to a maximum of 9 g’s. After these initial runs, a rapid onset rate (ROR) of 6 g/s is typically performed; this is for high performance fighters. Finally, a Tactical Aircraft Combat Maneuver (TACM) may be performed...
  12. I

    Deriving equations for pressure & number density for centrif

    Homework Statement Consider particles in a gas centrifuge. This device is used to separate gases of different molar mass by rotating a cylinder at high rates. Derive two equations: one for the pressure (P) and one for the particle number density (nv) as functions of M, r, w and T, where r is...
  13. P

    Uniform Circular Motion of a centrifuge

    Homework Statement A centrifuge is a device in which a small container of material is rotated at a high speed on a circular path. Such a device is used in medical laboratories, for instance, to cause the more dense red blood cells to settle through the less dense blood serum and collect at the...
  14. B

    How Does Water Pressure Change Inside a Spinning Test Tube?

    Homework Statement A test tube filled with water is being spun around in an ultra centrifuge with angular velocity ω. The test tube is lying along a radius, and the free surface of the water is at a radius r0. (a) Show that the pressure at radius r within the test tube is P =...
  15. G

    Centrifuge Problem (Circular Motion)

    Homework Statement A Centrifuge rotates at 12000rpm. What is this in radians per second? If the radius of this centrifuge is 150mm, what is the centripetal acceleration? Homework Equations v2 / r v = rω a = rω2 The Attempt at a Solution First I converted the 12000rpm...
  16. A

    Centrifuge and Radial Bouyancy in space

    Hi all, I want to calculate how tell if a particle in a centrifuge in deep space will move towards the rotation axis or to the rim of the fluid. There is no container walls. This is not a HW problem. I watched the video and wanted to learn more about this. (it is under the you-tube...
  17. C

    Speed/velocity of particles inside a centrifuge

    Which particle experiences the largest centripetal force in a centrifuge? (3.3) K/U T/I (a) a 0.05 g particle at a distance of 2 cm from the centre (b) a 0.05 g particle at a distance of 5 cm from the centre (c) a 0.1 g particle at a distance of 2 cm from the centre (d) a 0.1 g particle...
  18. T

    The Secrets of Light Speed: The Potential of a Light Speed Centrifuge

    something that has been banging around in my head for a few years. with the development of wonderfully large science devices like the LHC and ISS.. why have we not yet created a centrifuge capable of moving it's test bed at the speed of light? Honestly, with the exception of higher math, we...
  19. C

    What is the trajectory of an object thrown within a rotating centrifuge?

    Hi all. I posted a question here once before for a sci-fi writing project, and I'm back again to pick the brains of some people more left-brained than myself. Here's the scenario: Imagine you're in a spacecraft with a rotating centrifuge, to create artificial gravity for the astronauts...
  20. E

    Can we measure the effective mass of charge carriers using a centrifuge?

    Hello you all! What about a slightly exotic idea? Here I propose to measure the "effective" mass of charge carriers by centrifugal force. Electrons in vacuum have a mass, and when moving in a solid an other mass, often called "effective" (as if the vacuum mass were ineffective). Centrifugal...
  21. C

    Does a centrifuge weigh more when it's spinning?

    This may or may not be a crazy question but do centrifuges weigh more when they're spinning? Perhaps I'm misunderstanding g-force, weight and centrifugal force.
  22. M

    Why is human heart not a centrifuge pump

    Homework Statement Why is human heart not a centrifuge pump but positive displacement pump ? Homework Equations The Attempt at a Solution Maybe bcoz there is no continuous flow of blood. blood goes thru body in packets hence we hear heart beats..
  23. C

    How Does Centrifuge Radius Affect Blood Component Separation?

    Homework Statement Human blood contains plasma, platelets, and blood cells. To separate the plasma from other components, centrifugation is used. Effective centrifugation requires subjecting blood to an acceleration of 2000g or more. In this situation, assume that blood is contained in test...
  24. B

    Is there a machine or force that can reverse the effects of a centrifuge?

    Hey all, first post here on PF. This might be a stupid question, but I haven't been able to find if there is a machine that does the opposite of a centrifuge, specifically forcing material into the center of a circle. Or if there is a force that is reproducible on a small scale that does...
  25. I

    Need help getting started Cylindrical centrifuge

    A cylindrical centrifuge of radius 1m and height 2m is filled with water to a depth of 1m. As the centrifuge accelerates, the water level rises along the wall and drops in the center. (a) Find an equation of the parabola when the water level rises in terms of h, the depth of water at its...
  26. G

    Problem special relativity: Photon in a centrifuge

    I have to solve the following problem and I am also given the solution. I do not find the same answer as given and I do not understand why. Homework Statement Consider a centrifuge with radius r, spinning at a constant angular velocity ω. Two atoms E and A on the edge of the centrifuge are...
  27. S

    Flame in a centrifuge will go oblique?

    Flame in a centrifuge will go oblique (nearly parallel to the ground if the device is spinning extremely fast). Flame in a centrifuge will not point straight up but go more and more oblique as the rotational speed increases (see the picture) Experiment: 1) Put a candle in a preferably...
  28. I

    Calculating Normal Force of a Ball in a Centrifuge

    Hi. Could you please help me with the following problem. There is a ball in a centrifuge, which is moving with the velocity v. Assuming speed of the centrifuge is high enough so that the ball is moving inside it. How to calculate the normal force, acting on a ball from the centrifuge's walls? We...
  29. M

    Calculating Linear Speed of Test Tube in Centrifuge

    Homework Statement Find the linear speed of the bottom of a test tube in a centrifuge if the centripetal acceleration there is 5.3×104 times the acceleration of gravity. The distance from the axis of rotation to the bottom of the test tube is 7.3 . Homework Equations I have gotten...
  30. P

    Understanding Hermetic Seals on Centrifuges: Types and Conversion Possibilities

    Hi all, I am currently in the process of identifying a continuous lab scale liquid-liquid centrifuge for developmental work that may translate to our production unit. We know that only hermetically sealed unit would work for our type of separation, but the issue I encounter is that I either...
  31. B

    Centrifuge for astronaut training (tangential and normal acceleration)

    Homework Statement A centrifuge used for astronaut training starts moving from rest with a velocity Vi=8.5t[ft/sec]. It is know that a person loses consciousness when experiences an acceleration in the order of 10g. determine: a)how long can hold the astronaut in the centrifuge before...
  32. R

    Physics is behind how a centrifuge works

    I was wondering what the physics is behind how a centrifuge works and how to find the (radius dependent) g-force exerted along the centrifuge tubes. I look at some online sites like wiki etc. but they weren't really clear. Thanks.
  33. S

    Does Centrifugal Force Act During or After Spinning in a Centrifuge?

    Hello everyone, If some test tubes are placed in a centrifuge to separate the liquid in them, does the separation occur after the spinning is finished. I can't see how the centrifugal force can act when the tubes are spinning, does it act after it finishes. Thanks
  34. D

    How to find the mass of one cell using centrifuge data?

    Hi. I want to find the mass of one cell, using the data obtained during its centrfugal separation. Let me elaborate. I have a sample of cells. I have kept it in a test tube and used the centrifuge on it. Finally, I have 40k cells/ cc obtained near the rim of the test tube, at 150g setting...
  35. GRB 080319B

    How a centrifuge separates particles by density

    I am confused on how a centrifuge separates particles by density. In http://en.wikipedia.org/wiki/Centrifuge" , which appears to have something to due with an applied force or centrifugal force. It would seem like the more massive particles would remain closer to the axis of rotation due to...
  36. D

    Centrifuge - find centripetal acceleration

    Homework Statement You are designing a centrifuge to spin at a rate of 15,300 rev/min. (a) Calculate the maximum centripetal acceleration that a test-tube sample held in the centrifuge arm 14.7 cm from the rotation axis must withstand. 377361.36 m/s2 (b) It takes 1 min, 16 s for the...
  37. G

    Gravity ~ Acceleration ~ Centrifuge & GR

    Gravity & Acceleration are said to be fairly equivalent. This includes their respective effects on time dilation doesn't it? Is artificial gravity generated by centrifugal motion considered to be fairly equivalent to these?
  38. C

    Understanding Centrifuge Acceleration on Mercury

    Homework Statement A laboratory centrifuge on Earth makes n rpm (rev/min) and produces an acceleration of 3.70 g at its outer end. a.) What is the acceleration g's at a point halfway out to the end? Homework Equations a = (V^2)/R The Attempt at a Solution I really don't know...
  39. S

    Why does gravity give a constant acceleration and centrifuge?

    Hello everyone, Normally if there is 1 kg object and I apply 10 N force it would accelerate at 10m/s. Here the acceleration is determined by the mass of object. How does gravity in the absense of resistance make objects travel at a fixed acceleration? In a centrifuge a force equivalent to...
  40. P

    Centripetal acceleration centrifuge

    A centrifuge is a device in which a small container of material is rotated at a high speed on a circular path. Such a device is used in medical laboratories, for instance, to cause the more dense red blood cells to settle through the less dense blood serum and collect at the bottom of the...
  41. I

    A centrifuge have the speed of 1600rpm

    A centrifuge have the speed of 1600rpm. It takes 10 seconds for the centrifuge to reach maximim speed. How many turns does it make in these 10 seconds in the beginning. What is it's angular acceleration?
  42. K

    Centrifuge Acceleration Calculations

    Homework Statement A laboratory centrifuge on Earth makes n rpm (rev/min) and produces an acceleration of 3.40 g at its outer end. Part A: What is the acceleration (in g's) at a point halfway out to the end? Part B: This centrifuge is now used in a space capsule on the planet Mercury...
  43. V

    Angular Acceleration of a centrifuge

    A centrifuge in a medical laboratory rotates at an angular speed of 3400 rev/min. When switched off, it rotates 48.0 times before coming to rest. Find the constant angular acceleration of the centrifuge. Relevent equations: ωf = ωi + αt My work: I found out the time by (48 rev)(1min/3400...
  44. WCOLtd

    Is Mach's Principle incorporated into General Relativity?

    In this mock-up universe there exists two observers on a large disc of great mass, and there is a third observer a great distance away. In this scenario we take the observation of the spinning disc from the distant (third) observer. I was thinking about Special Relativity and Mach's Principle...
  45. A

    How Does a Centrifuge Separate Substances by Density?

    Homework Statement How does centrifuge work? a.) What is the physical principle behind the function of this device? b.) What is the difference between the stuff that goes to the top and the stuff that goes to the bottom. c.) What equation shows this? d.) When you centrifuge blood, plasma...
  46. A

    How Do You Calculate Rider Speed and Safety on a Centrifuge Carnival Ride?

    Homework Statement A ride has a diameter of 4.8 N and makes 2 complete rotations in 5.0s. a) Determine the speed of the rider. b)What is the centripetal acceleration of the rider? c) What is the coefficient of friction required to keep the rider from slipping downwards when the floor drops...
  47. D

    Cylindrical centrifuge filled with water.What happens first spills or bottom visible.

    1. Homework Statement A cylindrical centrifuge of raidus 1 m and height 2 m is filled with water to a depth of 1 meter. As the centrifuge accelerates, the water level rises along the wall and drops in the center; the crossection will be a parabola. a) Find the equation of the parabola in...
  48. T

    Turning saltwater into freshwater using a centrifuge?

    Just a thought that occurred to me while sitting around. Well?