Abstract: It is proposed to avoid an excessive formation of foam in the collection vessel of a protein separator by throttling the feed of air to a foam generator according to the foam generation rate in the separator. The foam generation rate in the separator can be measured by the amount of phase water that is separated in a second separator, which is located between the foam collection vessel and a first separator, in which second separator the mixture generated by the foam generator is freed from liquid constituents.

Abstract: It is proposed to avoid an excessive formation of foam in the collection vessel of a protein separator by throttling the feed of air to a foam generator according to the foam generation rate in the said separator. The foam generation rate in the separator can be measured by the amount of phase water that is separated in a second separator, which is located between the foam collection vessel and a first separator, in which second separator the mixture generated by the foam generator is freed from liquid constituents.

Abstract: In a propeller pump for an aquarium, starting-up of the rotor in the correct direction of rotation is guaranteed through the fact that a unit, which is formed by the propeller and the rotor of the pump, is disposed on a spindle in an axially displaceable and rotatable manner. If starting-up occurs in the wrong direction, said unit, and thereby the rotor, is drawn axially out of the magnetic field of the stator until the magnetic coupling between said stator and said rotor is no longer sufficient for further driving in the angular direction. The unit formed by the rotor and the propeller is then drawn back into the stator again by axial magnetic components of force, where a fresh opportunity of starting up again is imparted to it. It is guaranteed that the rotor will revolve in the correct direction after, at the latest, a few attempts at starting up.