Common shaking diameters of orbital shakers with the intention to cultivate cells in shake vessels are 19, 25, or 50 mm with flexible set speed ranges between 25 to 500 rpm. Of these, the smaller orbit shakers (19 and 25 mm) typically have a maximum of 400 or 500 rpm whereas the large 50 mm orbit shakers a maximum speed of 300 rpm. To cut it short: The smaller the orbit, the higher the maximum speed that can be set.
Oxygen transfer in shake flasks
The oxygen transfer rate in Erlenmeyer flasks is affected by the shaker (shaking orbit + agitation speed) and by the load (vessel design, material + fill volume). When an Erlenmeyer flask is shaken on an orbital shaker, the centrifugal forces associated with the flask rotation creates a swirl movement and throws the liquid up onto the walls (Fig. 3). A thin liquid film is formed and deposited on the flask wall and is replaced with each revolution. This film is the area of the oxygen transfer into the liquid. The overall rate of oxygen transfer depends on the rate of generation of fresh liquid surface, or the frequency with which the liquid film is replenished .