Beckman JA-20 Fixed Angle Rotor 

The JA-20, rated for 20 000 rpm, is a fixed angle rotor designed to centrifuge up to eight 50-mL tubes at a 34-degree angle to the axis of rotation. Used in Beckman Coulter J2, J6, and Avanti J series centrifuges, the rotor develops centrifugal forces that can efficiently pellet bacteria, cell membranes, and subcellular particles. Short-column methods (such as partially filled tubes) may also be used to isolate and band different classes of subcellular organelles. Up to 400 mL of gradient and sample can be centrifuged per run. The rotor body and lid are made of aluminum and are anodized for corrosion resistance—the rotor is black and the lid is blue. O-rings made of Buna N rubber in the lid and rotor body maintain atmospheric pressure inside the rotor during centrifugation, if they are properly lubricated. Two vertical pins in the rotor drive hole mate with grooves in the centrifuge drive hub (in older model centrifuges), or with drive hub teeth (new model centrifuges), to prevent the rotor from slipping during acceleration and deceleration