Apparatus and method for sensing diaphragm failures in reciprocating pumps

• US 4,781,535 A
• Filed: 11/13/1987
• Issued: 11/01/1988
• Est. Priority Date: 11/13/1987
• Status: Expired due to Fees

• Current Assignee: PLF Acquisition Corporation
• Original Assignee: Pulsafeeder Incorporated
• Inventors: Frawley, James J., Mearns, Richard L.
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US07/119,934
• Time in Patent Office: 354 Days
• Field of Search: 417/53, 417/63, 417/9, 417/383, 417/395, 92/5 R, 92/103 F, 92/103 M, 92/103 SD, 340/605, 340/679, 73/40
• US Class Current: 417/53
• CPC Class Codes: F04B 43/009 leakage control; pump systems with two flexible members; between the actuating element and the pumped fluid

Abstract

Apparatus for monitoring the diaphragm integrity in a diaphragm pump. A single continuous circuit trace is supported on a pump diaphragm. An electrical circuit is connected to the continuous circuit trace for measuring both the continuity and a potential ground fault condition between the circuit trace and pumping liquid. The circuit trace is formed in a configuration which resists the effects of strain induced by continuous flexing of the diaphragm.

Claims

1. An apparatus for determining a pump diaphragm failure comprising:

a single continuous circuit trace supported by said diaphragm, and insulated therefrom, and from a pumping medium, traversing substantially the entire surface area of said diaphragm;

an electrical circuit means connected to said continuous circuit trace for measuring both circuit trace continuity and a ground fault condition between said circuit trace and a pumping environment, whereby a diaphragm failure is detected when either said circuit trace electrical continuity is broken or said pumping environment comes into contact with said continuous circuit trace; and

,

an alarm connected to said electrical circuit for indicating said diaphragm failure.

2. The apparatus of claim 1 wherein said continuous circuit trace is disposed in a plurality of radial spokes on said diaphragm, beginning at the periphery of said diaphragm extending to the center thereof, each spoke connected to an adjacent radial spoke to form a single continuous circuit trace.

3. The apparatus of claim 2 wherein said radial spokes comprise a plurality of circumferential segments which decrease in size towards said diaphragm center providing a plurality of direction changes increasing the mechanical resistance to failure.

4. The apparatus of claim 2 wherein the single continuous circuit trace is a conductive trace formed on a printed circuit substrate, said substrate being bonded to said diaphragm, said conductive trace including an insulative film over said trace.

5. The apparatus of claim 1 wherein said continuous circuit trace changes direction a plurality of times while traversing said diaphragm surface, reducing strain on said circuit trace during flexure of said diaphragm.

6. The apparatus of claim 1 wherein said diaphragm comprises a continuous metallic circuit trace disposed on a substrate between first and second diaphragm halves forming a laminated structure.

7. The apparatus of claim 1 wherein said diaphragm is of stainless steel, and said single continuous trace is supported on a substrate bonded to said stainless steel diaphragm.

8. The apparatus of claim 7 further comprising a coating over said continuous circuit trace insulating said trace from said pumping medium.

9. The apparatus of claim 1 wherein said circuit trace is disposed on a substrate between two plastic diaphragm halves insulating said circuit trace from a fluid on one side of said diaphragm.

10. The apparatus of claim 9 wherein one of said diaphragm halves includes an integral annular flange.

11. An apparatus for determining a pump diaphragm failure comprising:

a single continuous circuit trace disposed on said diaphragm, insulated from a pumping environment, said continuous circuit trace traversing substantially all the surface area of said diaphragm;

a voltage supply connected through a first resistance element to one end of said circuit trace, and connected through a second resistance element to a second end of said circuit trace, whereby a current flow through said circuit trace is established;

a window comparator circuit connected to compare the voltage potential on one of said circuit trace ends with first an second threshold levels, whereby a fault is detected when said circuit trace either experiences an open circuit or when said pumping environment comes in contact with said circuit trace; and

,

failure indicating means connected to said comparator circuit for indicating said detected fault.

12. The apparatus of claim 11 wherein said continuous circuit trace is in the form of a double spiral beginning at the center of said diaphragm.

13. A method for detecting a failure of a diaphragm separating two liquid mediums, comprising:

disposing a continuous circuit trace over a major portion of said diaphragm;

measuring the continuity of said circuit trace;

measuring a current flowing between said circuit trace and one of said liquid mediums; and

indicating a failure when either said continuity of said circuit trace changes or said current flowing between said circuit trace and said liquid medium changes.

14. The method of claim 13 further comprising:

disposing said circuit trace between two halves of said diaphragm to insulate; and

fusing said two halves and circuit trace together to form a single diaphragm structure.

15. The method of claim 13 wherein said circuit trace is etched on a substrate fixed to said diaphragm.