The present invention relates to a flow metering device (10) for pulmonary function tests. Said device (10) comprises a sensing element extending in a longitudinal direction and defining an inner volume and an adapter unit (12), wherein said sensing element is a measuring tube (14) with open ends, and wherein a pressure difference inducing means is arranged in the measuring tube (14) between the open ends, said pressure difference inducing means comprises surfaces perpendicular to the longitudinal direction of the measuring tube (14), is in contact with the measuring tube (14) and partially occupies the measuring tube (14) in the inner cross section thereof, 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 (17, 27) are formed in the surfaces perpendicular to the longitudinal direction of the measuring tube (14) of said spoke arms.;The essence of the device (10) according to the invention is that the pressure offtake grooves (17, 27) start at the point of join of the spoke arms and at least some of the grooves open into respective through holes formed in the measuring tube (14), the measuring tube (14) is provided on the outer side thereof with pressure signal offtake stubs (18, 28), each stub has an internal channel, wherein each of the channels of said pressure signal offtake stubs (18, 28) is in communication with the inner volume of the measuring tube (14) via one of said through holes, and the adapter unit (12) is provided with reception bores capable of receiving the pressure signal offtake stubs (18, 28) in a detachable and pressure tight manner, the reception bores are in communication with pressure signal offtake stubs (13, 23) of the adapter unit (12) and each reception bore forms a continuous flow path with the respective channel of the pressure signal offtake stub (18, 28) received thereby when the measuring tube (10) becomes connected with the adapter unit (12), and pneumatic low-pass filters formed as an integral part of the adapter unit (12) are incorporated in between said reception bores and said pressure signal offtake stubs of the adapter unit (12) so as to ensure filtering out fluctuations of the pressure signals led away from the inner volume of said measuring tube (14) separately by means of the pressure offtake grooves (17, 27) located in opposite surfaces of said spoke arms.
展开▼
