Surprise, surprise: That low frequency wobble isn’t your colleague’s dubstep. Before your centrifuge leaps off the bench and into a spirited dance, power down to see what’s the matter before it catastrophically destroys itself, your samples and the entire lab.
Here are five unfortunately easy ways to wreck a centrifuge…and how to make sure it never happens in the first place!
1. By ignoring anything that sounds…well, odd.
Set it and forget? It’s a losing gamble to load your samples, press “Run” and then run away. The acceleration between 0 to 14,000RPM is your best chance to identify and fix the source of any strange sounding wobbles, hard vibrations, or pulses early on. Noises like that can be annoying, and seem harmless today, but over time it adds repeated stress to your equipment until a weakened part fails.
That’s why it’s a good idea to remain near your centrifuge until it stabilizes at a constant speed. The more you use it, the more you learn to recognize its quirks – including the click that cycles refrigeration and the normal vibrations while it spins up/down. On ours, the difference between a normal “hum” and excited “whirr” at speed depends whether or not the operator included the rotor lid.
Thankfully nearly all of the odd, new sounds that come from the centrifuge have easy-to-fix solutions.
2. Balancing by sight, not by weight
You take two tubes, both filled with an “equal” volume approximated by eye, and weigh them. In reality one tube’s weight is 1g heavier than the other. While approaching light speed (okay, maybe something more reasonable, like 14000 X g) during a routine spin, the linear path it travels would look something like a sine wave.
In other words, the rotor becomes a tilt-a-whirl!
Some equipment can automatically detect this hazardous scenario and save itself by sounding an alarm while braking down to 0, before the rotor rocks hard enough to damage its spindle. But don’t wait to find out whether or not your equipment has this feature: Rely on the best safety feature in the lab (yes, that’s you!) to save it instead.
Better yet, avoid unbalanced spins altogether by weighing your tubes and loading your rotor strategically.
3. Loading the rotor on autopilot
Of course, even loading a partially filled rotor one-off can sabotage all the effort made to balance your samples. Count the empty space on each side of them and you’ll know for sure that the load is balanced.
When dealing with odd-numbers of samples, remember to include a counterweight, like an equally weighted water tube!
However, if you want to increase your efficiency by loading a rotor by sight (and not by count), there’s a colorful way to do it. Grab your pens, count the tube holes and mark for visual cues for 3, 4, 5 or more tube spins. Jode Plank, thanks for showing how to “Pimp your Microcentrifuge”
4. Keeping the lid on the centrifuge during down time
Did you know that repeated freeze/thaw cycles can be harmful to equipment too? If you’ve ever set the thermostat to 4 degrees and let it sit indefinitely you may have come back to discover a sheet of frozen ice underneath the rotor. When it melts, there’s a lake.
Keep moisture from collecting in and around your centrifuge (it rusts the metal parts!) by opening the lid, turning off or idling it when not in use, and cleaning up any pools of water when you notice them.
5. Avoiding regular maintenance
A centrifuge is integral for many of your everyday bench techniques, so when it suddenly goes off-line you’re competing with neighbors for use of theirs. A lid that doesn’t stay open, or a lock that does not latch at the start of the run are minor inconveniences that can be fixed with a maintenance call!
Some centrifuges keep track of the total amount of time they’ve been spinning, but nothing beats a log book to record who uses the equipment, when, which rotor, spin time and speed. Now you’re able to schedule maintenance on your schedule – all to keep a good measure on the health of your equipment.
Have you ever wrecked your centrifuge and lived to spin again? Be brave! Share your story below.