Method and system for measurement of liquid level in a tank
First Claim
1. A method for measuring the level of substance in a tank in which the level is subject to changes and updating a prior collected average level of the substance comprising the steps of:
- (a) continuously determining values of differential pressure from within the tank;
(b) determining the instantaneous level of substance within the tank in response to the determined values of differential pressure;
(c) determining a difference relationship between the prior collected average level and the instantaneous level;
(d) determining a relative weighting factor for the prior collected average level and the instantaneous level which weighting factor varies in accordance with the difference relationship;
(e) determining a new collected average in response to the relative weighting factor; and
(f) repeating steps b, c, d and e in which the new collected average becomes the prior collected average in step (c).
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Accused Products
Abstract
The computer based remote tank telemetry system uses a method for updating a prior collected average level of substance in a tank. It continuously determines values of differential pressure within the tank and in accordance with the values of differential pressure determines the instantaneous level of substance within the tank. A prior collected average level is stored and is compared with each of the instantaneous values of level thus obtained. On the basis of this comparison a relative weighing factor is determined which weighs the relative contribution of the collected and instantaneous values in determining a new collected value. The new collected average is compared against a predetermined setpoint to determine whether the level of substance in the tank is too low. The results of this comparison can be displayed locally, and using a modem, communicated to a remote display. The method for determining the relative weighing factor has three tiers. The selection of the required tier is done in accordance with the levels compared.
102 Citations
14 Claims
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1. A method for measuring the level of substance in a tank in which the level is subject to changes and updating a prior collected average level of the substance comprising the steps of:
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(a) continuously determining values of differential pressure from within the tank; (b) determining the instantaneous level of substance within the tank in response to the determined values of differential pressure; (c) determining a difference relationship between the prior collected average level and the instantaneous level; (d) determining a relative weighting factor for the prior collected average level and the instantaneous level which weighting factor varies in accordance with the difference relationship; (e) determining a new collected average in response to the relative weighting factor; and (f) repeating steps b, c, d and e in which the new collected average becomes the prior collected average in step (c). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A system for measuring the level of substance in a tank in which the level is subject to change and updating a prior collected average level of the substance comprising:
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means for continuously determining the differential pressure of the tank for producing a differential pressure signal; means for determining the instantaneous level of substance within the tank in response to the differential pressure signal; means for determining a difference relationship between the prior collected average level and the instantaneous level; means for determining a relative weighting factor for the prior collected average level and the instantaneous level which weighting factor varies in accordance with the difference relationship; time-weighted averager means for determining a new collected average level in response to the relative weighting factor and for applying the new collected average level to said difference determining means as the prior collected average level; comparing means for determining when the new collected average is below a predetermined setpoint for producing a display signal; and remote display means for displaying the new collected average in response to the display signal. - View Dependent Claims (10, 11, 12, 13)
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14. A remote tank telemetry system having telecommunication means and a tank containing substance comprising:
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means for continuously determining the differential pressure of the tank for producing a differential pressure signal; means for determining the instantaneous level of substance within the tank in response to the differential pressure signal; means for determining a difference relationship between the instantaneous level and a prior collected average level; means for determining a weighting factor for the prior collected average level and the instantaneous level which weighting factor varies in accordance with the difference relationship; time-weighted averager means for determining a new collected average level in response to the relative weighting factor and for applying the new collected average level to said difference determining means as the prior collected average level; comparing means for determining when the new collected average is below a predetermined setpoint for producing a display signal; local display means for displaying the new collected average level; storage means for storing the collected average levels; means for coupling the time-weighted averager means to the telecommunication means; and remote display means coupled to the telecommunication means for displaying the collected average in response to the display signal.
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Specification