The fluidic flowmeter—A gas flowmeter based on fluidic dynamic oscillation

Abstract

Conventional diaphragm gas flowmeters are no longer aesthetically suitable to Japanese housing conditions and their sizes do not fit in the small Japanese houses. It is under these conditions that we are endeavouring to develop a new gas meter of a smaller size with good installation properties and safety functions. This new gas meter is to detect the gas flow rate based on the principle of fluidic oscillation instead of the conventional displacement method. The fluidic oscillation frequency decreases as the flow rate decreases until finally the oscillation ceases when the flow rate falls under a certain value. The lower-limit flow rate has been lowered to a rate close to the theoretical limit below which oscillation stops. Further, measurements have been made possible in a still lower flow rate range, using the IC flow sensor which detects fluid velocities. As the result, a new gas meter has been developed which has no mechanical moving parts. This gas meter is able to meter the flow rate of 3 ∼ 3000 ℓ h −1 at a maximum pressure loss of 225 Pa (air). Furthermore, the electric power consumption to operate the gas meter has been reduced to the minimum, and it is estimated that one 3 V battery of a capacity of 5000 mAh would keep the meter working for ten years.