Eppendorf 5402 Manual -

A: The manual notes that certain speed ranges (typically 11,500–12,500 rpm) may produce aerodynamic noise due to air friction on the rotor ridges. If the noise disappears above or below that range, it is normal. If constant, check the lid seal.

, ensuring that delicate proteins or DNA samples don't degrade while waiting for a run. The Ritual of the Spin

He turned to the chapter on preventative