Diaphragms for high pressure compressors and pumps

[57] ABSTRACT

Diaphragms are provided for high pressure compressors and pumps, the diaphragms having heat insulation properties, extended life and apparatus capable of detecting diaphragm leaks associated therewith.

Claims, 4 Drawing Figures

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DIAPHRAGMS FOR HIGH PRESSURE COMPRESSORS AND PUMPS

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to diaphragms for high pressure compressors and pumps and more particularly to diaphragms which reduce heat transfer with respect to the fluid being compressed or pumped by the diaphragm while at the same time providing for diaphragm leak detection.

2. Description of the Prior Art

It has heretofore been proposed to provide laminated diaphragms 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.

Serious difficulties have been encountered in high pressure service because of the fretting corrosion which occurs. In my application for patent filed June 3, 1970, Ser. No. 42,957 provisions are made for avoiding fretting corrosion and greatly increasing the life of a diaphragm.

The diaphragm there shown comprises a central metal plate with a film or coating interposed between the diaphragm and the casing.

Serious difficulties have heretofore been encountered, also with high pressure service, if the temperature of the fluid being compressed or pumped was at a temperature either too high or too low to be compatible with the fluid utilized for actuating the diaphragm.

Avoidance of contamination of the fluid being pumped or compressed is also highly important for proper operation.

SUMMARY OF THE INVENTION

In accordance with the invention a diaphragm assembly is provided for high pressure pumps and compressors which is free from fretting corrosion, which is suitable for greatly reducing heat transfer through the diaphragm assembly, and which provides for leak detection so that contamination of the working fluid can be avoided.

It is the principal object of the present invention to provide an improved diaphragm assembly for high pressure pumps and compressors which will obviate serious problems which have arisen with diaphragms heretofore employed and with particular respect to fretting corrosion, heat transfer and contamination of the fluid being pumped or compressed.

It is a further object of the present invention to provide a diaphragm assembly of the character aforesaid which will have a long life and which will be reliable in service.

Other objects and advantageous features of the invention will be apparent from the description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

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 transverse sectional view of a portion of a high pressure pump or compressor incorporating the diaphragm assembly in accordance with the invention;

FIG. 2 is an enlarged view of a portion of FIG. 1;

FIG. 3 is a fragmentary plan view on a smaller scale of an intermediate diaphragm element; and

FIG. 4 is a fragmentary plan view on a smaller scale of a different form of intermediate diaphragm element.

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 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 diaphragm mounting head 10, a lower diaphragm mounting head 11 and a diaphragm assembly 12 with an interposed limit plate 14.

The diaphragm assembly 12 may be moved in any desired manner such as by liquid acting on the underside thereof and effective through the limit plate 14 as in my prior Pat No 3,318,250.

A suitable packing 15 such as metallic rings may be provided in grooves 16 in the upper and lower heads 10 and 11.

The plate 14 has a plurality of fluid delivery bores 17 therethrough communicating with a dished face 18 for engagement and limiting of the movement of the diaphragm assembly 12. The upper head 10 has a fluid delivery bore 20 extending through the head 10 for delivery of fluid which has been compressed or pumped. Inlet and delivery valves (not shown) of any suitable type can be employed, such as those shown in U.S. Pat. No. 3,425,429 of Bacino and Bowen.

The lower head 11 has an inlet bore 21 connected to a supply of fluid (not shown) for delivery of fluid to actuate the diaphragm assembly 12 and pump or compress fluid above the assembly 12. The fluid used to actuate the diaphragm is generally a hydraulic fluid of mineral or spirit type and which can withstand a limited range of operating temperature variation.

The diaphragm assembly 12 has an upper diaphragm plate 25, a central plate 26 and a lower diaphragm plate 27.

The central plate 26 as viewed in FIG. 3 is circular and provided with a radial cut out or groove 30 to permit escape of any fluid which may leak through the upper plate 25 or the lower plate 27. As seen in FIG. 4, the plate 26α, in place of the groove 30, can have score lines 30α to permit of escape of fluid. The diaphragm plates 26 and 26α can be fabricated of a heat insulating plastic or of metal in accordance with the demands of a particular installation.

The upper diaphragm plate 25, the central plate 26 and the lower diaphragm plate 27 may be coated with a heat insulating friction reducing and particle absorbent film 31. The film 31 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 assembly 12 and the heads 10 and 11 and thereby reduce fretting corrosion, must be capable of absorbing small quantities of solid particles to prevent concentrated stresses from occurring and must have insulating characteristics.

A particularly suitable material for the film is available from E. I. du Pont de Nemours &amp; Co., Wilmington, Del., under the name Teflon (Compound 958—203), 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, Pa.; Ekonol, a polyester based on phydrobenzoic acid, available from Carborundum Corp., Niagara Falls, N.Y.; Emralon, available from Acheson Colloids Corp, of Port Huron, Mich.; and Vespel, a polyimid available from E. I. du Pont de Nemours &amp; Co., Wilmington,

A thickness of film in the range from about 0.2 to 5 1 .OOOths 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 not great it will flow. If this happens the stresses in the diaphragm assembly may exceed the “elastic limit” and a thinner film must be employed to prevent failure.

The film 31 can be applied to both sides of the upper and lower diaphragm plates 25 and 27 and the central plate 26.

The heads 10 and 11 may also have the film 31 on the face 18 of the lower head and the face 32 of the upper head if desired.

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The lower head 11 has a bore 35 therein which communicates with the opening between the upper and lower diaphragm plates 25 and 27 and extends to a threaded bore 36.

A pipe 37 is engaged with bore 36 and connected to a pres- 5 sure sensitive gauge 38 which has a pipe 39 connected to its other side and to a pressure switch 40 of conventional well known type. The switch 40 is connected to a circuit (not shown) which controls the hydraulic fluid pumped into the bore 21 for diaphragm actuation and may shut off the fluid 10 flow should pressure from leaks be effective at switch 40. A pressure relief valve 42 is connected to the switch 40 and a manually operated vent 43 is also connected to the switch 40. With the protective film as described coating the various parts of the diaphragm assembly 12 and the heads 10 and 11, high 15 or low temperatures of the fluid to be compressed or pumped which might be beyond the proper operating limits of the pumping fluid will not be adversely effective on the pumping fluid because of the temperature insulating and isolating qualities of the diaphragm assembly attendant on the use of the plu- 20 rality of films 31 with or without enhancement by a central plate 26 of low heat conductivity.

In addition should the upper diaphragm plate 25 or the lower plate 26 rupture or fail the leaking fluid will flow out through groove 30 in plate 26 or score line 30α in plate 26α 25 through bore 35, pipe 37 to pressure gauge 38 and through pipe 39 to pressure switch 40 so that the pressure rise will be apparent on gauge 38, and pressure switch 40 will cut off the flow of pumping fluid which actuates the diaphragm assembly 12 so that contamination of the fluid being pumped and 30 damage will not be inflicted on the diaphragm assembly.

It will thus be seen that apparatus has been provided with which the objects of the invention are attained.