Method of observing the pumping characteristics of a positive displacement pump

• US 4,705,459 A
• Filed: 08/19/1985
• Issued: 11/10/1987
• Est. Priority Date: 11/15/1984
• Status: Expired due to Fees

• Current Assignee: Dowell Schlumberger Incorporated (Schlumberger NV)
• Original Assignee: Dowell Schlumberger Incorporated (Schlumberger NV)
• Inventors: Dancer, Paul, Buisine, Paul H.
• Primary Examiner(s): Croyle, Carlton R.
• Assistant Examiner(s): Neils, Paul F.
• Application Number:
  US06/767,001
• Time in Patent Office: 813 Days
• Field of Search: 417/53, 417/63, 417/572, 92/5 R, 73/168, 137/554, 137/551
• US Class Current: 417/53
• CPC Class Codes: F04B 2201/0201 Position of the piston
• CPC Class Codes: F04B 2201/0207 Number of pumping strokes in unit time
• CPC Class Codes: F04B 2201/0601 Opening times
• CPC Class Codes: F04B 51/00 Testing machines, pumps, or pumping installations
• CPC Class Codes: Y10T 137/8242 Electrical

Abstract

The invention relates in particular to measuring the delivery rate of a positive displacement pump comprising at least one piston (3) driven with reciprocating movement in a chamber (2), which chamber is connected to an inlet circuit (4) via an inlet valve (5) and to an outlet circuit (6) via a delivery valve (7). The number of cycles performed by the pump in unit time are counted, and simultaneously its volumetric efficiency is measured, thereby enabling its real delivery rate to be deduced. Its volumetric efficiency may be measured by means of position sensors (17, 18) detecting the closure and opening instants of the delivery valve, with another sensor determining the instants at which the piston (3) passes through its end positions.

Claims

1. A method determining the flow rate delivered by a positive displacement pump in operation, the pump having at least one piston driven with a reciprocating motion in a chamber, which chamber is connected to a feed circuit for fluid to be pumped via an inlet valve and to an outlet circuit via a delivery valve, said valves being mechanically independent of the piston, the method comprising:

(a) counting the number of cycles performed by the pump in unit time;

(b) determining a corrected volume of the pump by;

(i) measuring the partial volumes of the chamber swept by the piston between an instant at which the piston passes through its end position of maximum engagement in the chamber and a closure instant of the delivery valve, and also between an instant at which the piston passes through its opposite end position and an opening instant of the delivery valve;

(ii) subtracting the two partial volumes from the volume swept by the piston; and

(c) multiplying the number of cycles per unit time by the corrected volume of the pump so as to provide the flow rate.

2. A method according to claim 1, characterized by the fact that the instants at which the piston passes through its end positions are determined by measuring the varying position of the piston as a function of time.

3. A method according to claim 1, characterized by the fact that the instants at which the piston passes through its end positions are determined as being equidistant between the consecutive instants at which the piston passes a predetermined position.

4. A method according to claim 1 characterized by the fact that the closure instants of the delivery valve are determined by detecting the shocks produced by the valve closing against a delivery valve seat.

5. A method according to claim 1 characterized by the fact that the closure and/or opening instants of the delivery valve are determined by accoustically detecting the noise of fluid escaping between the valve and a delivery valve seat.

6. A method according to claim 1 characterized by the fact that the closure and/or opening instants of the delivery valve are determined by measuring their positions which vary as a function of time relative to a delivery valve seat.

7. A method according to claim 1 characterized by the fact that the closure and/or opening instants of the delivery valve are determined by measuring the internal pressure in the chamber which varies as a function of time.

8. A method of determining the flow rate delivered by a positive displacement pump in operation, the pump having at least one piston driven with a reciprocating motion in a chamber, which chamber is connected to a feed circuit for fluid to be pumped via an inlet valve and to an outlet circuit via a delivery valve, said valves being mechanically independent of the piston, the method comprising:

(a) counting the number of cycles performed by the pump in unit time;

(b) determining a corrected volume of the pump, by;

(i) sensing the position of the piston and at least one of the valves as a function of time, and determining at least the time differences between the instant at which at least one of the valves closes and/or opens and the passages of the piston through its end positions;

(ii) ascertaining from the time differences, partial volumes of the chamber swept by the piston during such time differences; and

(iii) subtracting the partial volumes from the volume of the chamber;

(c) multiplying the number of cycles per unit time by the corrected volume of the pump so as to provide the flow rate.

9. A method according to claim 8 characterized by the fact that the closure and/or opening instants of the valve are determined by measuring the pressure in the inlet and/or outlet circuits and/or in the chamber which vary as a function of time.