Flow velocity measuring apparatus and methods using sensors for measuring larger and smaller flow quantities

Abstract

A flowmeter capable of measuring an accurate quantity of flow over a wide range of the quantity of flow. A measurement zone ( ) for smaller quantity of flow and a measurement zone ( ) for larger quantity of flow are determined inside a flow path ( ) of a pipe ( ). Regulating strainers ( ) for regulating the flow of a gas ( ) are disposed inside the measurement zone ( ) for smaller quantity of flow by dividing the flow path ( ) into a plurality of narrower flow paths ( A). A mean flow velocity of the gas ( ) flowing through each of a plurality of narrower flow paths ( A) becomes substantially equal. A part of the gas ( ) reaches nozzles ( ) erected across flow velocity sensors ( ) for smaller quantity of flow and is accelerated by the operation of these nozzles. The flow velocity sensors ( ) inside the measurement zone ( ) for smaller quantity of flow output signals corresponding to the flow velocity of the gas ( ) passed through the narrower flow path ( ) and accelerated by the nozzles ( ) in the range of the smaller quantity of flow. Flow velocity sensors ( ) for larger quantity of flow in the measurement zone ( ) for lager quantity of flow output signals corresponding to the flow velocity of the gas ( ) in the range of the larger quantity of flow.