Flow through pressure sensor structured to remove dead volume

A system for removing dead volume in a sensor assembly of a mass flow controller, the system comprising:

• a valve assembly in fluid communication with fluid in a primary flow path;
• a pressure sensor assembly in fluid communication with fluid in the primary flow path, the pressure sensor assembly located in a bypass of a primary flow path, the pressure sensor assembly comprising:
• a first reservoir coupled to a first pressure transducer having a first side with a first pressure sensing face disposed on the first side;
• and having a port in fluid communication at a location in a sampled flow path;
• a second reservoir that is coupled to a second pressure transducer having a second side with a second pressure sensing face disposed on the second side, the first side of the first pressure sensing face facing the second side and the second pressure sensing face, the second reservoir fluidly coupled to the first reservoir through a flow through path, wherein a restrictor is disposed between the first reservoir and the second reservoir, the restrictor located between the first side with the first pressure sensing face and the second side with the second pressure sensing face such that the first side and the second side face the restrictor;
• an inlet from the primary flow path to the first reservoir located between the first side with the first pressure sensing face and the restrictor;
• an outlet to the primary flow path from the second reservoir located between the second side of the second pressure sensing face and the restrictor;
• and
• wherein the first pressure transducer and the second pressure transducer are communicatively coupled with the valve assembly and configured to remove dead volume by providing a flow through path across the first and second sensing faces.

A method for operating a mass flow controller with a reduced dead volume in a sensor assembly of the mass flow controller, the method comprising:

• routing fluid from a primary flow path to a bypass through a port into a first reservoir coupled to a first pressure transducer having a first side with a first pressure sensing face disposed on the first side;
• routing fluid from the first reservoir into a second reservoir that is coupled to a second pressure transducer through a flow through path configured to remove dead volume, the second pressure transducer having a second side with a second pressure sensing face disposed on the second side, the first side with the first pressure sensing face facing the second side with the second pressure sensing face, and then routed back to the primary flow path, the fluid having flowed across the first and second sensing faces, wherein a restrictor is disposed between the first reservoir and the second reservoir, the restrictor located between the first side with the first pressure sensing face and the second side of the second pressure sensing face,
• an inlet to the first reservoir located between the first side of the first pressure sensing face and the restrictor;
• and
• an outlet to the second reservoir located between the second side of the second pressure sensing face and the restrictor.