Thermal mass flowmeter and mass flow controller, flowmetering system and method

A mass flow control system for use in an industrial process in which at least one process fluid is used in producing a product, said process fluids being toxic, reactive, or both, the flow of each process fluid being controlled by a mass flow controller with the process fluids being used under a variety of temperature and pressure conditions, each mass flow controller comprising:

• means for sensing fluid flow through a passage by which a process fluid is directed to a process location at which it is used;
• valve drive means for operating a fluid flow valve to control the mass flow rate of process fluid into the process based upon the sensed fluid flow rate and the established set point;
• and
• control means for controlling said valve drive means and including processor means for accessing a calibration curve for its associated mass flow controller to determine the amount of process fluid to be delivered by said fluid flow valve based upon said sensed flow rate and said set point, said calibration curve being derived from a calibration data set accumulated for the respective mass flow controller over the operational range thereof and using a calibration fluid which is not the process fluid with which said mass flow controller is used in performing the process, said control means accessing said data set for said process fluid and from which said calibration curve for a process fluid is created;
• and,
• said system including process controlled means for establishing a set point for each process fluid controlled by a mass flow controller and based upon process temperature and pressure conditions for each respective process fluid.

An analog mass flow controller for use in a manufacturing process to control the flow of a process fluid used in the process, the process fluid being used under a variety of temperature and pressure conditions and said process fluid being toxic, reactive, or both, and the analog mass flow controller comprising:

• means for sensing fluid flow through a passage by which said process fluid is directed to a process location at which it is used and for producing an analog signal representative thereof;
• valve drive means for operating a fluid flow valve to control the mass flow rate of said process fluid based upon the sensed fluid flow rate and an established set point for said process fluid;
• and,
• control means for controlling said valve drive means, said control means including means for accessing a calibration curve for the mass flow controller to determine the amount of process fluid to be delivered by said fluid flow valve based upon said sensed flow rate and said set point, said calibration curve being derived from a calibration data set accumulated for a representative mass flow controller over the operational range thereof and using a calibration fluid which is not the process fluid now being controlled by said mass flow controller, said control means accessing said data set for said process fluid and from which said calibration curve for the process fluid is created.

A digital mass flow controller for use in a manufacturing process to control the flow of a fluid used in the process, the process fluid being used under a variety of temperature and pressure conditions and said process fluid being toxic, reactive, or both, and the digital mass flow controller comprising:

• means for sensing fluid flow through a passage by which process fluid is directed to a process location at which it is used and for producing an analog signal representative thereof;
• means for converting said analog signal from said sensing means to a digital signal;
• valve drive means for operating a fluid flow valve to control the flow rate of process fluid into the process based upon the sensed fluid flow rate and an established set point for said process fluid;
• and,
• control means responsive to said digital signal from said sensing means for controlling said valve drive means, said control means including means for accessing a calibration curve for the mass flow controller to determine the amount of process fluid to be delivered by said fluid flow valve based upon said sensed flow rate and said set point, said calibration curve being derived from a calibration data set accumulated for the mass flow controller over the operational range thereof and using a calibration fluid which is not the process fluid now being controlled by said mass flow controller, said control means accessing said data set for said process fluid and from which said calibration curve for the process fluid is created.

A mass flow controller for use in a manufacturing process for controlling the flow of one of a variety of fluids used in the process, the process fluid controlled by the controller being used in the process under a variety of temperature and pressure conditions and said process fluids possibly being toxic, reactive, expensive, difficult to dispose of, or a combination thereof, the mass flow controller comprising:

• means for sensing fluid flow through a passage by which a process fluid is directed to a process location at which it is used;
• valve drive means for operating a fluid flow valve to control the mass flow rate of process fluid into the process based upon the sensed fluid flow rate and an established set point for the process fluid;
• and,
• control means for controlling said valve drive means, said control means including means for accessing a calibration curve for the mass flow controller to determine the amount of process fluid to be delivered by said fluid flow valve based upon said sensed flow rate and said set point, said calibration curve being derived from a calibration data set accumulated for the mass flow controller over the operational range thereof and using a calibration fluid which is not the process fluid now being controlled by said mass flow controller, said control means accessing said data set for said process fluid and from which the calibration curve for the process fluid is created.