Differential pressure flow meter

A method of monitoring and regulating a flow rate of a fluid composition generated by a nasal cannula, the method comprises:

• configuring the nasal cannula with a differential pressure flow meter by introducing the fluid composition to a fluid restriction unit via an upstream compartment to generate a high-pressure fluid flow, wherein the differential pressure flow meter comprises
• the fluid restriction unit, comprising:
• the upstream compartment, a downstream compartment, a first fluid outlet port on the upstream compartment, a second fluid outlet port on the downstream compartment, and an orifice element having a centric bore;
• wherein the orifice element is located at a junction face of the upstream compartment and the downstream compartment, and is in a circular cross section of the fluid restriction unit, and wherein the orifice element is configured to flow a fluid from the upstream compartment to the downstream compartment through an upstream side of the orifice element to a downstream side of the orifice element via the centric bore;
• wherein each of the upstream compartment and the downstream compartment are in a shape of a hollow cylinder having substantially same inner diameter (D) and wall thickness;
• and
• a differential pressure transducer, comprising:
• a diaphragm compartment having a high-pressure side diaphragm, a low-pressure side diaphragm, a first sensor operatively coupled to the high-pressure side diaphragm, and a second sensor operatively coupled to the low-pressure side diaphragm;
• and
• a chamber having a high-pressure compartment and a low-pressure compartment, wherein the high-pressure compartment and the low-pressure compartment are separated by the diaphragm compartment, wherein the high-pressure compartment is in fluid communication with the upstream compartment of the fluid restriction unit via the first fluid outlet port, and wherein the low-pressure compartment is in fluid communication with the downstream compartment of the fluid restriction unit via the second fluid outlet port;
• wherein the high-pressure fluid flow is in fluid communication with the high-pressure compartment of the chamber via the first fluid outlet port;
• passing the fluid composition through the downstream compartment of the fluid restriction unit to generate a low-pressure fluid flow;
• wherein the low-pressure fluid flow is in fluid communication with the low-pressure compartment of the chamber via the second fluid outlet port;
• simultaneously measuring a deformation of the high-pressure side diaphragm caused by the high-pressure fluid flow by the first sensor, and a deformation of the low-pressure side diaphragm caused by the low-pressure fluid flow by the second sensor;
• and
• converting the deformation into the electrical signal which is numerically digitally displayed and visually displayed to monitor and regulating a flow rate of the fluid composition generated by the nasal cannula.