Patent ID: 8585608

Claim:
A flow metering device for pulmonary function tests, comprising a sensing element extending in a longitudinal direction and defining an inner volume and an adapter unit, wherein said sensing element is a measuring tube with open ends, and wherein a pressure difference inducing means is arranged in the measuring tube between the open ends, said pressure difference inducing means comprises surfaces perpendicular to the longitudinal direction of the measuring tube, is in contact with the measuring tube and partially occupies its inner cross section, said pressure difference inducing means is formed by spoke arms in pairs joined in a single point, the spoke arms in a pair close a given angle with one another, and pressure offtake grooves are formed in the surfaces perpendicular to the longitudinal direction of the measuring tube of said spoke arms, wherein the pressure offtake grooves start at a point of join of the spoke arms and at least some of the grooves open into respective through holes formed in the measuring tube so as to provide radial averaging for the full inner cross section of the measuring tube, the measuring tube is provided on its outer side with pressure signal offtake stubs, each stub having an internal channel, wherein each of said channels of said pressure signal offtake stubs is in communication with the inner volume of the measuring tube via one of said through holes, and the adapter unit is provided with reception bores capable of receiving the pressure signal offtake stubs in a detachable and pressure tight manner, said reception bores are in communication with pressure signal offtake stubs of the adapter unit and each reception bore forms a continuous flow path with the respective channel of the pressure signal offtake stub received thereby when the measuring tube becomes connected with the adapter unit, and pneumatic low-pass filters formed as integral parts of the adapter unit are incorporated in between said reception bores and said pressure signal offtake stubs of the adapter unit so as to ensure filtering out fluctuations of the pressure signals led away from the inner volume of said measuring tube separately by means of the pressure offtake grooves located in opposite surfaces of said spoke arms.