| CPC G01F 1/69 (2013.01) [G01F 1/696 (2013.01); G01F 15/068 (2013.01)] | 20 Claims |
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1. A fluid flow measuring apparatus configured to detect a characteristic of fluid flow in a tube when the tube is located in the fluid flow measuring apparatus, comprising:
a housing including a throughway configured to accept the tube;
a thermal source located in the housing and adjacent the throughway;
a first sensor positioned adjacent the throughway and spaced from the thermal source in an upstream direction;
a second sensor positioned adjacent the throughway and spaced from the thermal source in a downstream direction such that the thermal source is located between the first sensor and second sensor, and the first sensor and second sensor are symmetrically located about the thermal source; and
a controller connected to the first sensor and second sensor and configured to detect a characteristic of the fluid flow in the tube, wherein detection is dependent on the symmetrical relationship between the first sensor and the second sensor about the thermal source, the controller further configured to initiate an alarm signal when the characteristic of the fluid flow is an alarm characteristic of the fluid flow wherein,
the controller is further configured to:
measure a variation of differential sensor temperature over time during conditions of no fluid flow in the tube, to determine a no flow response value;
measure a variation of differential sensor temperature over time during conditions of fluid flow in the tube to obtain a response value, and subtract the no flow response value from the response value, to determine a calibrated response value; and
integrate the calibrated response value over time to determine an integrated calibrated response value.
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