✅ × g (RCF — Relative Centrifugal Force)

• This is a measure of force, specifically how many times greater than gravity (g) the centrifugal force is.

• It depends on the speed (rpm) and the rotor radius.

• It is the true measure of how hard your sample is being spun.

 

✅ rpm (Revolutions Per Minute)

• This is a measure of speed, how fast the rotor is spinning.

• It does not tell you directly how much force (g) is applied, unless you also know the rotor radius.

 

🔁 Relationship Between g and rpm:

To convert between rpm and RCF (g), use this formula:

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Where:

• RCF is in ×g

• r is the rotor radius in centimeters

• rpm is revolutions per minute

 

🧪 Example:

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If your rotor has a radius of 10 cm:

RCF==1.118×10−5×10×(10,000)2=11,180g

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So 10,000 rpm with a 10 cm rotor gives about 11,180 × g, not 10,000 × g.

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🔍 Summary:

• ✅ g (RCF) is what really matters for separating samples.

• ❌ rpm alone is not enough to compare centrifuge settings across machines or rotors.

• ✅ Use RCF to standardize protocols.