Centrifuge
Terms
undefined, object
copy deck
- What 3 things are centrifuges used for?
-
-simulating gravity
-seperating two things with diff densities and one's a liquid
-removing moisture - What is the diff btn centrifugal and centripetal force?
-
Centrif pulls out
Centrip is pulling in - What 3 factors affect force?
-
mass
velocity (angular)
radius - What's the equation for force?
- F = mrw'2
- What is RCF?
- relative centrifugal force
- what is RCF for?
- allows comparison of centrifuge force between different machines
- What's the equation for RCF?
- RCF = (1.12x10^-5)rN^2
- What factors affect settling in a centrifuge, and what law tells us that?
-
Stoke's law
V = kr^2g(dp-dL)n -
Ok, in plain english please...
What 6 factors affect settling? -
-Velocity of particles
-Gravity
-Particle shape
-Particle density
-Particle size/radius
-Liquid density and viscosity -
how does particle shape alter
settling?
Density?
size/radius? -
the smoother, the faster.
the more dense, the faster.
the bigger, the faster. - why do RBCs settle below WBCs in the Hct?
- RBCs are more streamlined and dense than WBCs and these factors simply carry more weight than size.
- what are the components of the electric motor in a centrifuge?
-
Armature windings, field coils, carbon brushes, etc.
Potentiometer
Brake - What's better, a mechanical or electrical brake?
- Electrical - prevents bumping, quicker, more gradual.
- what are the 2 types of centrifuge heads?
-
-Fixed angle (conical)
-Horizontal (swinging - What type of centrif is the hct?
- Fixed angle (conical)
- What are advantages of the fixed angle?
-
-Gains higher speeds
-Less friction
-Particles travel less distance
-Better seperaton of supernat in shorter period of time. - What are the disadvantages of fixed angle?
- Particles pack at an angle so you can't measure their surface.
-
What are the advantages of a Horizontal (swinging) centrif?
Disadvantages? -
Allows exact measurement of sediment.
Partcls move entire tubelength, swinging tubes create air resistance. - what are 4 clinical applications of centrifuges?
-
1. Seperation of solids/liquids
2. Hematocrit
3. Special purposes
4. Centrifugal analyzer - what are special purposes?
-
-cell washing
-blood processing (during surgery) - What are Centrifugal analyzers defined as?
- analytical instruments in clinical chemistry that use centrifugal force to transfer liquids and monitor several simultaneous chemical rxtns.
- what is the advantage of centrifugal fast spectrophotometry?
- it allows discrete analysis of each sample, seperated by an actual physical barrier at all times.