Used for measuring the exhaled air flow, the device comprises a flow head and screens attached to show the variation in pressure on either of the sides of the screen. It converts the measured value and displays the pressure readings for the operator. The set up comprises seals amid the screens and pressure taps. The improved sealing and knife edges on tube adaptors are positioned adjacent to the screens to ensure accuracy in the measurements. The apparatus obtains accurate measurements with varied speeds and includes a disposable element held by the holder. Available in readily assembled and self- contained kit, flow sensing devices provides output in form of pressure’s direct proportionality to air flow.