A hydrofoil impeller wherein the tip edge is straight and has a right angle with a radius extending from the central axis to the tip edge. In the central hub and in each of the blades the number of holes in each group of first and second holes is at least five. The pattern in which the holes are arranged in each of the respective groups of holes is elliptical having a center and a major axis which is substantially parallel to the radius and placed at a distance therefrom. The leading edge is, in the direction of rotation, behind an imaginary radial line intersecting the central axis of the shaft and the center of the ellipse, the leading edge being at an angle of 502 in relation to the radial line. The area of the blade is divided into four planar portions by three straight bends.

The present invention refers to the use of hydrofoil impellers for the preparation of polymer polyols and to a method for preparing a polymer polyol, which comprises reacting a base polyol, at least one ethylenically unsaturated monomer and a macromer or a preformed stabilizer in the presence of a free-radical initiator and optionally a chain transfer agent in a reactor, wherein said reactor is stirred by means of a stirring system comprising a shaft rotatable about its longitudinal axis, and a plurality of radially extending hydrofoil impellers mounted on the shaft and respectively axially spaced apart and wherein the reactor does not contain baffles.

A method and apparatus for aerating wine or spirits to reduce the astringency, or bitterness of wine or spirits. Astringency is often a result of tannins in wine or spirits, particularly noticeable in full bodied red wines. Aeration causes oxygen to dissolve in wine or spirits where it will oxidize tannin compounds, thereby reducing the astringent flavor. The method employs an apparatus wherein a hand held unit having a battery, switch or button, electrical wiring and electric motor cause rotation of a drive-shaft and aeration head. The aeration head is immersed in wine or spirits, the switch activated causing rotation of the aeration head creating a plurality of fine air bubbles resulting in large wine or spirit to air surface area simultaneous with stirring to ensure uniform oxygenation and aeration of wine or spirits throughout the container. The process may be extended until the desired reduction in astringency is achieved.

Stirrer (M) that includes at least two blades and is able to be fixed to a rotary shaft, wherein each blade has a leading edge facing the fluid to be stirred and a trailing edge facing away from the leading edge, and wherein each blade is obtained by bending a flat metal sheet, each blade having two longitudinal bends, the length of each bend being greater than 60% of the maximum radius of the blade

The present invention refers to the use of hydrofoil impellers for the preparation of polymer polyols and to a method for preparing a polymer polyol, which comprises reacting a base polyol, at least one ethylenically unsaturated monomer and a macromer or a preformed stabilizer in the presence of a free-radical initiator and optionally a chain transfer agent in a reactor, wherein said reactor is stirred by means of a stirring system comprising a shaft rotatable about its longitudinal axis, and a plurality of radially extending hydrofoil impellers mounted on the shaft and respectively axially spaced apart and wherein the reactor does not contain baffles.