The Centrifuge Incident

Friday, January 29th, 1999 I loaded the ultracentrifuge, turned on the machine, waited for it to reach it's final operating speed of 55,000 RPM, then walked away. Saturday, I walked into the common equipment room to finish off my routine plasmid prep. I noticed the centrifuge was not spinning and the machine wasa little out of place. I checked the counter and saw that it the machine completed 10 million revolutions before it stopped. That amounts to 3 hours and this was about 20 hours later. I started trying to open up the machine but the door wouldn't budge, even with the electronic catch moved out of the way. Clearly, the centrifuge had a major failure. Thankfullly no one was hurt. On Tuesday the Beckman technician came and we opened it up and viewed the destruction.

The rotor split right down the middle and for those of you who don't know, the rotor is a 20 pound piece of titanium that was spinning at 55,000 RPM at the moment it split in half. At 55,000 RPM the outside edge of the rotor is moving at about the velocity of a .22 caliber long rifle bullet at the muzzel (near 1000 feet per second). At some point on friday night two10 pound hunks of titanium hit the inside walls of the centifuge. The points where the pieces of rotor crashed into the steel barrel are shown below. Although it is hard to say exactly what happened, metal fatigue is a very likely explanation for the following reasons. First, the rotor was manufactured in 1986 and was covered for 10,000 hours of operation or 5 years, whichever comes first. Second, the machine ran at full speed for several hours before the accident. If something was wrong with set up, it probably would have shown up long before 10 million revolutions. Third, this kind of thing happens. It's rare but that is why the rotor is contained so carefully. According to the technician, given the age of the rotor and the age of the centifuge, if it had not happened to me, it would have been someone else. Enjoy the pictures and get your rotors checked.