Method and apparatus for fault detection and correction in Coriolis effect mass flowmeters

A method for detecting cracks in the flow tubes of an operating Coriolis effect mass flowmeter, said method comprising the steps of:

• generating a signal indicative of the present vibration frequency of said flow tubes of said operating Coriolis effect mass flowmeter;
• generating a signal indicative of present drive power required to drive said flow tubes of said Coriolis effect mass flowmeter to vibrate at said present vibration frequency;
• determining that said signal indicative of present vibration frequency is below a vibration frequency nominal value by a predetermined amount;
• determining that said signal indicative of present drive power is above a drive power nominal value by a predetermined amount;
• and
• generating an output signal indicating the presence of a crack in said flow tubes in response to said determination that said present vibration frequency is below said vibration frequency nominal value and in response to said determination that, concurrently, said present drive power is above said drive power nominal value.

An apparatus for detecting a fault condition in an operating Coriolis effect mass flowmeter, said apparatus comprising:

• input means connected to said Coriolis effect mass flowmeter for receiving information including measured values regarding present operating parameters of said Coriolis effect mass flowmeter, wherein said information includes the vibration frequency of said Coriolis effect mass flowmeter and the drive power of said Coriolis effect mass flowmeter;
• means for selecting at least one value selected from the group consisting of values of present operating parameters of said Coriolis mass flowmeter, slopes of said values of said present operating parameters, and curvatures of said values of said present operating parameters;
• memory means for storing fault signature information regarding at least one fault condition represented by said present operating parameters;
• output means for indicating the occurrence of said fault condition in operation of said Coriolis mass flowmeter;
• and
• detection means connected to said input means and connected to said output means and connected to said memory means, for comparing said at least one value to said fault signature information to detect the occurrence of said fault condition and to apply a signal to said output means indicating the occurrence of said fault condition.