Abstract: The invention relates to a control system for adjusting the setting of a damper (9) in a ventilation duct (8) and maintaining a substantially constant pressure at a selected region in the ventilation duct, the system comprising a cylinder (1) having a vertical cylinder axis and housing a readily movable, pressure-responsive device (2), which together with the cylinder defines a pressure space. The pressure space (22) communicates with the ventilation duct at the aforementioned selected region, and drive means (11, 12) are provided for adjusting the damper setting in response to the position of the pressure-responsive device, so as to maintain a constant pressure. The inventive system is characterized in that the pressure-sensitive device (2) has a mass which corresponds to a selected pressure at the aforementioned region in the duct and is intended to balance the pressure force acting on the device.

Abstract: A measurement unit for determining gas flow through a conduit by means of measuring pressure differential over an orifice arranged in the conduit (1), and to a measuring means designed to be included in such measurement unit. The purpose of the invention is to achieve a measurement unit and a measuring means which produce reliable readings and are of simple construction. This is achieved by means of an orifice centrally arranged in a section of the conduit (1) made as a flat circular disc (2) perpendicular to the central axis of said section. Round pressure measurement boxes (3) are arranged close to the sides of the disc. The inner chambers (13) of the boxes communicate with the space close to the disc and immediately outside the lateral wall (11) of the box via aperture means (10) between the lateral wall edge portion adjacent to the disc and the surface of the disc.

Abstract: An air flow regulating apparatus comprising a regulator housing having an air inlet and an air outlet and an air passage extending from the inlet to the outlet. In the passage there is provided at least one movable damper blade attached to a shaft extending transversely to the flow direction in the air passage and having its ends pivotally journalled in the air passage side walls. One of the shaft ends extends through an opening in one of said side walls and has the form of a counterweight neck on the outside of the housing, there being attached to said neck an adjustable mass body system. The damper blade is angular in cross section and has a plane forward blade portion and a plane rear blade portion enclosing an obtuse angle with said forward blade portion.

Abstract: A jointing piece for sealingly connecting pipes, said piece having at either end elastic sealing means arranged in their operational position to engage sealingly with the inside of the respective connecting pipe end. In the area adjacent either jointing piece end there is provided a sealing means comprising two outwardly open mutually separated channels running circumferentially side by side and being formed in the jointing piece wall and an elastic sealing ring placed therein. Before the jointing piece end is inserted into the respective pipe end, said ring is placed in the channel nearest the end of the pipe jointing piece, and during insertion the ring is caused, by contact with and relative movement between the jointing piece and pipe, to roll over to and down into the posterior second channel where the ring assumes its operational sealing position.