# How to Keep Your Centrifuge Alive

According to the Occupational Safety and Health Administration, “the majority of all centrifuge accidents result from user error.” That’s right, it’s us. Many a machine has been destroyed by an unsuspecting scientist just in it for the pellet. The more expensive the machine, the more sensitive and the easier it is to break.

Does your centrifuge sound like an aggressive car engine when it’s turned on?

We know that a centrifuge needs to be balanced, but what else can we do to give these pricey monsters a long, successful tenure in the lab?

Here are some tips:

## Fully Attach the Rotor

After gently placing the rotor on the drive shaft, I always try to lift it to make sure it’s not loosely attached. A spinning rotor that isn’t fully attached can quickly turn into a weapon, destroying the inside of the machine. Broken centrifuge = broke PI = get ready to start sterilizing and reusing gloves and pipette tips.

## Keep Your Centrifuge Below Maximum Speed

The maximum speed of your sweet new centrifuge is 26,000 RPM! You proceed to pop in some tubes and begin to centrifuge at 26,000 RPM for 20 minutes while you grab a quick lunch. When you get back to the lab, your lab mates are huddled around the broken centrifuge.

You: Why is this happening to me?
Centrifuge Company: Because you’ve gone over the max speed.
You: But I didn’t intend to! I specifically made sure that I was at 26,000 RPM!
Centrifuge Company: What was the density of the solution you centrifuged?
You: *freaked out silence*

If the solution you are spinning has a density above 1.2 g/mL, the centrifuge should be run at a lower speed than the max. That’s because maximum speed plus the tubes and solution puts too much strain on the rotor. If you want to find the real maximum speed to use based on a solution’s density, use this formula:

where ρ=density.

## Wash Rotors with Dish Soap

Rotors are often made of steel or aluminum. They are subject to corrosion with all the washes, spills and leaks that they go through in a lifetime. Rotors are protected from corrosion by an anodized coating. Washing the rotor is necessary, but washing with strong acids and bases and lab detergents can wear the anodized coating off, exposing the rotor to rust. Rusty rotors, while a good band name, are damaged goods and should not be used.

## Use the Right Tubes

If for some reason your tubes break, melt, or disintegrate during centrifugation, samples will leak and throw the delicate balance off. This can mean a damaged rotor, or bits of tube flying around wreaking havoc (remember that a small mass with all of that centripetal force can cause some serious damage).

Before putting tubes in the rotor, it’s good to know:

• Can the tubes you’re using withstand the temperature you want to centrifuge at?
• Can these tubes hold the solution in them? For example, plastic tubes will fall apart when there’s chloroform in the solution.
• Do the tubes need to be filled completely? Some tubes crush in if not filled completely (e.g., heat-sealed tubes).

## Take Advantage of Free Resources

Lastly, read the manual before centrifuging and before attempting to fix anything. If you’re not sure what to do, call for help. If your institution doesn’t already have someone on staff to handle centrifuge problems, many manufacturers will send a professional to take care of it for you.

Read more from Bitesize Bio to learn other important centrifuge safety tips, including keeping O-rings lubricated, and how many swinging buckets need to be in place before you start your centrifuge.