US 3668978 A
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nited States atent Bowen 14 1. June 13, 1972  DIAPHRAGMS FOR HIGH PRESSURE 3,049,931 8/1962 Lang et ai. ..92/103 x COMPRESSORS AND PUMPS 2,867,241 1 1959 Fitzharris.... 4  Inventor: John C. Bowen, Huntingdon Valley, Pa. 3 9 022 5/1966 Bolger 92/102  Assignee: The DurironCompany, Inc., Dayton, Ohio Primary ExaminerMartin P. Schwadron 7 Assistant ExaminerLeslie J. Payne  Ffled' June 1970 Attorney-Zachary T. Wobensmith, 2nd  Appl. No.: 42,957 Y  ABSTRACT US. Cl. A diaphragm is provided for pressure pumps and com- [5 IIIIL .L. v pressors operating at pressures of the order of and [5 8] F leld of Search ..92/103, l03 SD, 102, 98 higher h diaphragm having a greatly extended fife and prising a metal diaphragm with a friction reducing and dirt ab- [5-6] Reference? cued sorbent film in contact with the diaphragm to prevent fretting UNITED STATES PATENTS corrosion. The film can be on the diaphragm, or the clamping portions of the casing in engagement with the periphery of the 2,551,217 5/1951 Martin ..'..92/l03 X diaphragm, or on both. 2,667,786 2/1954 Spaulding .....92/l03 X 2,736,332 2/1956 Simmons... ..92/103 X 5 Claims, 2 Drawing Figures r 27 Z9 Z5 L 28 DIAPHRAGMS FOR HIGH PRESSURE COMPRESSORS AND PUMPS BACKGROUND OF THE INVENTION l. Field of the Invention This invention relates to diaphragms for high pressure pumps and compressors and more particularly to such a diaphragm having a protective film in contact therewith.
2. Description of the Prior Art It has heretofore been proposed to use metal diaphragms, usually of steel. One type of equipment in which such diaphragms have been used is shown in my prior U.S. Pat. No. 3,318,250.
Such diaphragms are particularly susceptible to fretting corrosion,near the periphery of the diaphragm cavity and at which location the highest stresses occur in the diaphragm and heretofore had an expected life of about 20 hours.
Various laminations of diaphragms have heretofore been proposed for low pressure service. Examples of such diaphragms are shown by McFarland, U.S. Pat. No. 2, 918,089 and Lang, U.S. Pat. No. 3,049,931. These and similar diaphragms are not suitable for high operating pressures of the order of 5,000 psi and higher.
SUMMARY OF THE INVENTION In accordance with the invention a metal diaphragm is provided for high pressure pumps and compressors having a friction reducing and particle absorbent film in contact therewith, the film being carried on the diaphragm or on the portions of the casing with which the diaphragm engages at and contiguous to the periphery of the diaphragm cavity.
It is the principal object of the present invention to provide a diaphragm for high pressure pumps and compressors having a greatly extended life over those heretofore available.
It is a further object of the present invention to provide a diaphragm which is protected and has its useful life greatly enhanced in a simple but effective manner.
Other objects and advantageous features of the invention will be apparent from the description and claims.
BRIEF DESCRIPTION OF THE DRAWING The nature and characteristic features of the invention will be more readily understood from the following description taken in connection with the accompanying drawings forming part thereof, in which:
FIG. 1 is a fragmentary sectional view of a portion of a high pressure pump or compressor illustrating the manner of increasing the life of the diaphragm; and I FIG. 2 is an enlarged view ofa portion ofFIG. 1.
It should, of course, be understood that the description and drawings herein are illustrative merely and that various modifications and changes can be made in the structure disclosed without departing from the spirit of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now more particularly to the drawings a fragmentary portion of a high pressure pump or compressor similar to that in my prior U.S. Pat. No. 3,318,250, is shown and includes an upper mounting head 10, carrying a fluid supply pipe 11 for delivery of fluid to be compressed or pumped, and a fluid delivery pipe 12 for delivery of fluid which has been compressed or pumped. Inlet and delivery check valves 15 and 16, of any-desired type can be employed, suitable valves being shown in the U.S. Pat. No. 3,245,429 of Bacino and Bowen. 1
The upper mounting head 10 is held in alignment with a lower diaphragm mounting head 18. The head 18 is shown as provided with a central cylindrical opening 19 within which a diaphragm limit plate 20 is carried.
The plate 20 has a plurality of fluid delivery bores 21 therein communicating with a dished face 22 for engagement by and limiting the movement of a metal diaphragm 25, of steel or the like.
A suitable packing 23, such as a metallic or rubber ring, may be provided in a groove 24 in the head 18.
The upper diaphragm mounting head 10 has a dished face 26 providing with the diaphragm 25 a compression chamber 27 and limiting the movement of the diaphragm 25 in the other direction.
The diaphragm 25 may be moved in any desired manner such as by liquid acting on the underside thereof and impelled through the limit plate 20 as in my prior U.S. Pat. No. 3,318,250.
In accordance with the invention a friction reducing and/or particle absorbent film is interposed between the metal of the diaphragm 25 and the metal of the adjoining heads 10 and 18 between which the diaphragm 25 is held. The film should be suitable for the process to be carried out, adherent to metal and not subject to removal by scuffing, resistant to flow when subjected to stress and motion, must allow limited sliding movement to occur between the diaphragm 25 and the heads 10 and 18 and thereby reduce fretting corrosion, and must be capable of absorbing small quantities of solid particles to prevent concentrated stresses from occurring.
A particularly suitable material for the film is available from E. I. duPont de Nemours & Co., Wilmington Delaware, under the name Teflon (compound 8203), this being a fluorocarbon resin with modifiers dispersed in an organic solvent for spray application.
Other suitable materials for the film are Rulon R-75, a fluorocarbon resin with modifiers dispersed in an organic solvent for spray application available from Penn-Dixon Corporation, Clifton Heights, Pennsylvania; Ekonol, a polyester based on p-hydrobenzoic acid, available from Carborundum Corp., Niagara Falls, New York; Emralon, available from Acheson Colloids Corp. of Port Huron, Michigan and Vespel, a polyimid available from E. I. du Pont de Nemours & Co., Wilmington, Delaware.
A thickness of film in the range from about 0.2 to 5 thousandths of an inch has been found'to be satisfactory, dependent on the strength of the film and on the bond. If the strength of the film is too great it will not flow and the desired action may not be obtained unless a thinner film is employed. The metal diaphragm 25 may have a film 28 as just described adherent thereto on both side faces thereof, or the heads 10 and 18 may each have a film 29 as just described adherent thereto, or both the diaphragm 25 may have films 29 adherent thereto and the heads 10 and 18 may also have films 29 ad-. herent thereto.
With protective film, as described, interposed between the metal of the diaphragm 25 and the metal of the heads 10 and 18 the expected life of the diaphragm 25 has been found to be more than 500 hours as compared with metal to metal diaphragms and heads of about 20 hours.
1. In combination a metal diaphragm member,
metal diaphragm mounting members,
said mounting members each having an interior convexoconcave dished face in opposed relation to' the dished face of the other mounting member and providing a diaphragm chamber between said faces,
said mounting members having diaphragm holding portions surrounding said dished faces in retaining engagement with said diaphragm member at the periphery of said diaphragm member,
said mounting members each having fluid passageways extending from its said face,
said diaphragm faces limiting the movement of said diaphragm member in opposite directions, and friction reducing means interposed between said metal diaphragm member and each of said mounting members effective at the holding portions and with respect to con tacting portions of said diaphragm member and said face,
said interposed means comprising a friction reducing film disposed at each side of said diaphragm member and in adherent engagement with one of said members.
2. The combination defined in claim I in which opposite side faces of said diaphragm have said film thereon in thickness.
in adherent engagement therewith. 5. The combination defined in claim 1 in which The combination defmed in claim 1 in which said film is a fluorocarbon resin with modifiers in an organic said film is disposed on each of said mounting heads. 4. The combination defined in claim 1 in which 5 said film is in the range from 0.5 to 5 thousandths of an inch solvent.