System and method for filtering output in mass flow controllers and mass flow meters

A method for filtering an indicated flow in a mass flow controller comprising:

• (A) outputting said indicated flow as said filtered indicated flow for a delay period;
• (B) when it is determined that said indicated flow reaches an approximately steady state, outputting said indicated flow as said filtered indicated flow;
• (C) determining if said indicated flow has remained within an allowable deviation from a baseline;
• (D) if said indicated flow has remained within said allowable deviation, continuing to output said indicated flow as said filtered indicated flow;
• and
• (E) if said indicated flow has not remained within said allowable deviation:
• (1) outputting a value from within said allowable deviation as said filtered indicated flow;
• (2) determining if said indicated flow has exceeded a buffer;
• (3) if said indicated flow has exceeded said buffer:
• a) engaging a timer having a clock limit;
• b) determining if said indicated flow has returned to within said buffer prior to said timer reaching said clock limit;
• and
• c) if said indicated flow has not returned to being within said buffer prior to said timer reaching said clock limit, outputting said indicated flow as said filtered indicated flow;
• and
• d) if said indicated flow has returned to being within said buffer prior to said timer reaching said clock limit:
• i) outputting said indicated flow as said filtered indicated flow if said indicated flow is within said allowable deviation;
• and
• ii) continuing to output said value from within said allowable deviation as said filtered indicated flow if said indicated flow is not within said allowable deviation but is within said buffer.

A method for filtering an indicated flow in a mass flow meter comprising:

• filtering said indicated flow to derive an intermediate filtered indicated flow;
• deriving a weighted first derivative of said intermediate filtered indicated flow;
• and
• summing said intermediate filtered indicated flow and said weighted first derivative of said intermediate filtered indicated flow to derive a filtered indicated flow.

A mass flow controller operable to:

• determine if an indicated flow is within an allowable deviation of a baseline;
• if said indicated flow is within said allowable deviation, output said indicated flow as a filtered indicated flow;
• and
• if said indicated flow is not within said allowable deviation, output a value that is within said allowable deviation as said filtered indicated flow.

A system for filtering an indicated flow comprising a mass flow meter operable to:

• filter an indicated flow to derive an intermediate filtered indicated flow;
• derive a weighted first derivative of said filtered indicated flow;
• and
• derive an indicated flow from said sum of said intermediate filtered indicated flow and said weighted first derivative of said intermediate filtered indicated flow.