Abstract: A peak flow meter has a flexible resilient vane which is rigidly mounted by one end and which has its other end engaged with a slider indicator which slides in a slot formed in a curved wall of the casing. In use, the human subject blows into the casing through a mouthpiece. The vane is bent by the expiration which vents through the part of the slot between the slider and the mouthpiece. The slider stops at the furthest point from the mouthpiece to which it is moved by the vane and that point is an indication of the peak expiratory flow of the human subject.

Abstract: A respirometer comprises a casing in which a circular chamber is formed. A rotor is mounted for rotation within the chamber and comprises vanes carried by a spindle. A circular wall of glass ceramic material closes an end of the chamber. A pair of aligned radial arms are carried by the spindle between the vanes and the circular wall. Each arm carries a samarium cobalt magnet and rotates with the spindle within a recess in the circular wall. One of the magnets has its north pole adjacent the circular wall and the other has its south pole adjacent the circular wall. A bistable Hall effect sensor is mounted on the opposite side of the circular wall from the rotor with its sensitive region in as close proximity to the rotational path of the magnets as dimensional accuracy will allow.

Abstract: An instrument comprises a rotor within a stator. The stator is mounted within a casing which forms a gallery which extends circumferentially around the stator, and an inlet which communicates with the gallery at one end and which projects radially outwardly with respect to the stator from that end. Oblique slots are formed in the stator so that fluid flow to be measured is passed from the gallery to the interior of the stator through them. A barrier in the gallery constrains fluid to flow around the gallery in one direction only.

Abstract: A fluidic flowmeter for measuring the respiratory function of infants or children comprises a duct through which the infant or child breathes. A convergent pair of supply passages are provided for directing a pair of jets across the duct towards a pair of receiver passages which communicate with and diverge from the duct, the jets merging part way across the duct. A pressure tapping is provided in each receiver passage for sensing the static pressure of fluid flow at a respective point in each receiver passage and there is a differential pressure sensitive transducer having an input connected to one end of the pressure tappings and another input connected to the other pressure tapping. In a preferred embodiment the two receiver passages are connected together to define a loop, the dimensions and configuration of that part of the loop with which the tappings communicate being such that the flow passed each tapping is laminar.

Abstract: The invention provides means for controlling the displacement of a universally pivoted member which is subject to a force, such as the force of the wind tending to move the member about its universal pivot, so that a predetermined law of displacement in relation to the applied force is maintained.