Fluidic gas metering system

摘要

A fluidic gas metering system interposed in a line running from a gas source to a user site to meter the gas stream being supplied to the user in a broad flowrate range defined by a low flowrate band at the lower end of the range, a medium band at the middle of the range and a high band at the upper end thereof. The system includes an input chamber which receives a stream of pressurized gas from the source and an output chamber from which the gas is supplied to the user. Intercoupling the chambers are three gas flow channels. The first channel is defined by a first fluidic generator operative only when the flowrate of the gas lies in the low band to yield periodic pulses whose frequency is proportional thereto. The second channel is defined by a second fluidic generator operative only when the flowrate of the gas lies in the medium band to yield periodic pulses whose frequency is proportional thereto. The third channel is defined by a bypass passage operative only when the stream lies in the high band, the bypass acting to divide the gas stream between the second and third channel whereby the second generator then meters flowrate in the medium band. The periodic pulses yielded by the first and second generators are processed and totalized to provide accurate readings of the gas consumed by the user throughout the full range.