초록 ▼

A pressure signal from a differential pressure transducer is dynamically compensated for error, such as zero point drift, due to time passage or temperature change. A processor associated with a pressure transducer employs an algorithm to continuously monitor the pressure signal to determine when si

A pressure signal from a differential pressure transducer is dynamically compensated for error, such as zero point drift, due to time passage or temperature change. A processor associated with a pressure transducer employs an algorithm to continuously monitor the pressure signal to determine when signal characteristics indicate zero signal level. Then the algorithm determines a current correction factor or updates a previously determined correction factor, and records the current correction factor in a non-volatile memory as a function of ambient temperature. When the signal characteristics indicate other than a zero signal level, such as when differential pressure is non-zero, the algorithm recalls from memory and applies the most recently determined correction factor for a corresponding ambient temperature. Suitable time intervals for determining a current correction factor are found by monitoring the process signal and seeking those time periods when the signal is both calm and quiet, i.e., when signal level is both below a preset threshold and fluctuating very little. Taking a time derivative of the output signal and comparing the derivative to a predetermined maximum value can determine the latter.

대표청구항 ▼

A pressure signal from a differential pressure transducer is dynamically compensated for error, such as zero point drift, due to time passage or temperature change. A processor associated with a pressure transducer employs an algorithm to continuously monitor the pressure signal to determine when si

A pressure signal from a differential pressure transducer is dynamically compensated for error, such as zero point drift, due to time passage or temperature change. A processor associated with a pressure transducer employs an algorithm to continuously monitor the pressure signal to determine when signal characteristics indicate zero signal level. Then the algorithm determines a current correction factor or updates a previously determined correction factor, and records the current correction factor in a non-volatile memory as a function of ambient temperature. When the signal characteristics indicate other than a zero signal level, such as when differential pressure is non-zero, the algorithm recalls from memory and applies the most recently determined correction factor for a corresponding ambient temperature. Suitable time intervals for determining a current correction factor are found by monitoring the process signal and seeking those time periods when the signal is both calm and quiet, i.e., when signal level is both below a preset threshold and fluctuating very little. Taking a time derivative of the output signal and comparing the derivative to a predetermined maximum value can determine the latter. ns generates when said dynamic flow valve is closed embodies a more accurate measurement of the rate at which such fluid is flowing through said dynamic flow adapter as compared to said electrical signal that said means generates when said dynamic flow valve is open. 4. The dynamic flow adapter claimed in claim 1 wherein said predetermined threshold amount is approximately 99 CFM. 5. The dynamic flow adapter claimed in claim 1 wherein said means is a differential pressure transducer that is pneumatically tapped into said input chamber by one passageway and into said output chamber by another passageway. 6. The dynamic flow adapter claimed in claim 1 wherein said dynamic flow valve includes: (a) a valve stem longitudinally disposed within said supplemental passage, said valve stem having a shaft and a contact plate attached to one end of said shaft, said contact plate having (i) a front surface against which such fluid flowing from said input passage into said input chamber impacts and (ii) a rear surface serving as a first spring seat; (b) a valve head attached to an opposite end of said shaft; (c) a second spring seat formed annularly within an input side of said supplemental passage; (d) a valve seat formed annularly within an output side of said supplemental passage; and (e) a spring concentric to said shaft and compressively disposed between said first and second spring seats, said spring for biasing said valve head against said valve seat; such that when the rate at which such fluid flows into said input chamber is (i) less than or equal to said predetermined threshold amount, the force with which such fluid impacts said contact plate is insufficient to overcome said bias of said spring thereby leaving said valve head seated against said valve seat and (ii) greater than said predetermined threshold amount, the force with which such fluid impacts said contact plate is sufficient to overcome said bias of said spring and thereby move said valve head off said valve seat to an extent determined, up to a fully open position, by the rate at which such fluid flows into said input chamber. 7. The dynamic flow adapter claimed in claim 1 wherein said second diameter of said secondary orifice is selected so that the rate at which such fluid flows through said dynamic flow adapter when said dynamic flow valve therein is fully opened is equivalent to that which said dynamic flow adapter would allow if said dynamic flow adapter had a single orifice measuring approximately 19/64ths of an inch in diameter. 8. The dynamic flow adapter claimed in claim 7 wherein said means is a differential pressure transducer that is pneumatically tapped into said input chamber by one passageway and into said output chamber by another passageway. 9. The dynamic flow adapter claimed in claim 8 wherein said electrical signal that said differential pressure transducer generates when said dynamic flow valve is closed embodies a more accurate measurement of the rate at which such fluid is flowing through said dynamic flow adapter as compared to said electrical signal that said differential pressure transducer generates when said dynamic flow valve is open. 10. The dynamic flow adapter claimed in claim 9 wherein said predetermined threshold amount is approximately 99 CFM. 11. The dynamic flow adapter claimed in claim 10 wherein said dynamic flow valve includes: (a) a valve stem longitudinally disposed within said supplemental passage, said valve stem having a shaft and a contact plate attached to one end of said shaft, said contact plate having (i) a front surface against which such fluid flowing from said input passage into said input chamber impacts and (ii) a rear surface serving as a first spring seat; (b) a valve head attached to an opposite end of said shaft; (c) a second spring seat formed annularly within an input side of said supplemental passage; (d) a valve seat formed annularly within an output side of said supplemental passage; and (