System, devices and methods for measuring differential and absolute pressure utilizing two MEMS sense elements

A method for determining a mass flow rate of a flowing gas in a fluid system, comprising the step(s) of:

• configuring the fluid system so as to include a first pressure tap, a second pressure tap, a restrictive pressure device and a temperature sensing device;
• wherein the first and second pressure taps are spaced from each other such that the second pressure tap is downstream of the first pressure tap in a direction of flow;
• wherein the restrictive pressure device is disposed between the first and second pressure taps such that the first pressure tap is at a higher pressure than the second pressure tap;
• wherein the temperature sensing device is coupled to and arranged in the fluid system so that the temperature sensing device measures a temperature of the flowing gas and provides an output of the measured temperature;
• providing an absolute pressure sense element and first fluidly coupling the absolute pressure sense element to one of the first or second pressure taps so as to thereby measure an absolute pressure representative of the flowing gas at the respective pressure tap to which it is fluidly coupled and providing an output thereof;
• providing a differential pressure sense element and second fluidly coupling the differential pressure sense element to each of the first and second pressure taps so as to measure a differential pressure of the flowing gas between the first and second pressure taps and providing an output thereof;
• wherein said first and second fluidly coupling further includes disposing a non-compressible medium between the respective absolute and differential pressure sense elements and the respective first and second pressure taps;
• and
• using the outputs of the measured temperature, absolute pressure and differential pressure to determine a mass flow rate of the flowing gas in the fluid system.

An apparatus for measuring absolute and differential pressure of a flowing fluid in a fluid system, comprising:

• a housing including a plurality of cavities that are fluidly coupled in spaced relation to the fluid system and so as to be fluidly coupled to the flowing fluid;
• a sensing module mounted to the housing;
• and
• wherein the sensing module includes:
• an absolute pressure sense element that is first fluidly coupled to one of the plurality of cavities so as to thereby measure an absolute pressure representative of the flowing fluid to which the said one cavity is fluidly coupled to,
• a differential pressure sense element that is second fluidly coupled to said one cavity and to another of the plurality of cavities so the differential pressure sense element measures a differential pressure of the flowing fluid to which said first and another cavities are fluidly coupled to, and
• a non-compressible medium being disposed in said one cavity and said another cavity so that the non-compressible medium is located between the respective absolute and differential pressure sense elements and the flowing fluid to isolate the sense elements from the flowing fluid while allowing the sense elements to be responsive to the pressure of the flowing fluid.