Abstract: A method and an apparatus for control of the movement of a control piston an air control valve for a compressed air-operated double diaphragm pump, wherein the control piston is moved between the end positions in a control cylinder having inlet bores and outlet bores for the compressed air. The control piston is adjusted by a control medium. The method includes initially maintaining the control piston in an end position by a holding device against the pressure of the control medium for a predetermined period of time or until a counterpressure reaches a predetermined pressure level. Subsequently, the control piston is moved with a pushing force which is always greater than the maximum frictional forces. The holding device operates independently of the movement of the pump diaphragm, preferably using elastically, magnetically, or electromagnetically operating structural elements. The control cylinder includes separate connections for a control medium for moving the control piston.

Abstract: The production of wood material particles into board or panels, such as chipboard, fiberboard, OSB panels, MDF panels and the like, involves coating the particles with a binder free of any hardener. The coated particles are deposited on a support surface in the form of a mat and then are compressed. While the particles are beng compressed in a press, an acid or basic hardener in a gaseous phase or in a binary phase with a gaseous carrier agent, is introduced across and into the surface of the mat or directly into the interior mat. The compression of the mat can be performed either in a continuous double band press or a discontinuous single or multi-platen press. In a double band press, two press bands are arranged in opposed relation and the hardener is introduced into the mat in a wedge-shaped inlet zone between the press bands. The hardener flows through openings in the press band onto the surface of the mat.