US 5,313,842 AGranted

Pump station flowmeter with sudden high inflow change detector

AssigneeMarsh-McBirnes, Inc.

InventorsLawrence B. Marsh, John D. Wright

Life of this patent

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Abstract

A pump station flowmeter is disclosed including a sudden high inflow change detection circuit for eliminating from a series of emptying characteristic calculations taken over a period of time those measurements which are outside of a predetermined acceptance range. The wet well dimensions, level detector signals, clock signals and pump status signals are supplied as inputs to both a volume rate of change calculator and to the sudden high inflow change detector. In the event of an undesirable measurement, the sudden high inflow change detection circuit operates a gate to isolate the volume rate of change calculator from the emptying characteristic calculator that calculates outflow. A flow integrator is provided for calculating volume per cycle from the volume rate of change signal, and an inflow calculator serves to produce inflow from the volume per cycle signal.

Claims13

Dependent claims

Apparatus for determining the emptying characteristics of a wet well system (4), including a source of liquid (2) discharging into the wet well to fill the same, pump means (8) for pumping liquid out of the wet well, a source of pump status signals, means for generating a clock signal, and level sensing means for producing level signals corresponding with the level of the liquid at any given time;

the improvement which comprises:
(a) volume rate of change calculator means (310, 410, 510) for calculating a signal corresponding with the volume rate of change relative to time (dV/dt);
(b) emptying characteristics calculator means (318, 418, 518) for calculating the emptying characteristics of the system as a function of said volume rate of change level, clock and pump status signals;
(c) memory means (320, 420, 520) for storing said emptying characteristics;
(d) gate means (314, 414, 514) operable between enabled and disabled conditions for connecting said volume rate of change calculator means with, and disconnecting said volume rate of change calculator means from, said emptying characteristics calculator means, respectively;
and
(e) sudden high inflow change detector means (316, 416, 516) for operating said gate means to the disabled condition when the rate of inflow into the wet well suddenly changes above a predetermined value.

4 more elements

Apparatus for determining the emptying characteristics of a wet well (4) including a source of liquid (2) discharging into the wet well to fill the same, pump means (8) for pumping the liquid out of the wet well, a source of pump status signal, a source of clock signals, a continuous level sensor for making the level measurements, and means for detecting the differential pressure across the inlet and outlet sides of the wet well pump means, comprising:

(a) volume rate of change calculator means (510) responsive to the dimensions of said wet well, said level detecting means, and said clock signals for providing a first signal (dV/dt) that is a function of the rate of change of the volume of liquid in the wet well with respect to time during at least some portion of the wet well fill time;
(b) curve fitting means (552) for producing an interpolated inflow signal (Q.sub.in) as a function of time during the pump on time;
(c) calculator means (518) responsive to said inflow signal for calculating the wet well emptying characteristics (Q.sub.out) as a function of the differential pressure across the pump;
(d) gate means (514) connecting said volume rate of change calculator means with said emptying characteristics calculating means, said gate means being operable between enabled and disabled conditions;
(e) means including a memory (520) for storing said emptying characteristics;
and
(f) detector means (516) responsive to a predetermined sudden inflow change for operating said gate means to said disabled condition thereby isolating said curve fitting means from said rate of change calculator means, said detector means including:
(1) second derivative calculator means (562) for obtaining the second derivative of level with respect to time (d.sup.2 1/dt.sup.2);
and
(2) zero crossing detector means (564) for detecting a point of inflection in the level and thereby indicate said sudden inflow change.

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/815,756Filed 2 Jan 1992
Granted: 24 May 1994
Term ends: Not estimatedThe source records don’t support an estimate.

Classification11 codes

B67D 7/08
Details or accessories: arrangements of devices for controlling, indicating, metering or registering quantity or price of liquid transferred
B67D 7/16
Arrangements of devices for controlling, indicating, metering or registering quantity or price of liquid transferred: arrangements of liquid meters
G01F 1/007
Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow: by…
G01F 9/001
Measuring volume flow relative to another variable, e.g. of liquid fuel for an engine: with electric, electro-mechanic or electronic means