COMPOSITE DIAPHRAGM FOR DIAPHRAGM PUMP

Abstract

A composite diaphragm for a diaphragm pump or the like is formed of a flexible membrane with an outer edge, an inner part and a flexible membrane portion connecting the outer edge to the inner part. This flexible membrane is formed at least partially from an ultrahigh-molecular-weight polyethylene and another layer is formed from an elastomer selected from the group consisting of acrylonitrile-butadiene rubber, hydrogenated acrylonitrile-butadiene rubber, ethylene-propylene-diene rubber, chloroprene rubber, styrene-butadiene rubber, fluororubber, silicone rubber and fluorosilicone rubber.

Claims

1. In a composite diaphragm for a diaphragm pump, diaphragm being formed of a flexible membrane with an outer edge, an inner part and a flexible membrane portion connecting the outer edge to the inner part, the improvement wherein: the flexible membrane is formed at least partially from an ultrahigh-molecular-weight polyethylene and another layer is formed from an elastomer selected from the group consisting of acrylonitrile-butadiene rubber, hydrogenated acrylonitrile-butadiene rubber, ethylene-propylene-diene rubber, chloroprene rubber, styrene-butadiene rubber, fluororubber, silicone rubber and fluorosilicone rubber.

2. The composite diaphragm according to claim 1, wherein the membrane has at least one face formed entirely from the ultrahigh-molecular-weight polyethylene.

3. The composite diaphragm according to claim 1 wherein the membrane is a laminate.

4. The composite diaphragm according to claim 3, wherein the membrane has a cover layer of the ultrahigh-molecular-weight polyethylene and the other layer.

5. The composite diaphragm according to claim 4, wherein the cover layer directly abuts the other layer.

6. The composite diaphragm according to claim 4, wherein the cover layer abuts the other via an adhesion-promoting layer.

7. The composite diaphragm according to claim 1, wherein the cover layer is on or embedded in the other layer.

8. The composite diaphragm according to claim 4, wherein the cover layer has a thickness of between 0.15 and 1.5 mm.

9. The composite diaphragm according to claim 8, wherein the thickness is between 0.2 and 1.2 mm.

10. The composite diaphragm according to claim 1, wherein the flexible membrane portion is formed with a plurality of ridges.

11. The composite diaphragm according to claim wherein the inner part forms a chamber adapted to hold an insert.

12. Use of the composite diaphragm according to claim 1 in a diaphragm pump.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0025] The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

[0026] FIG. is an isometric view of a composite diaphragm according to the invention;

[0027] FIG. 2 is a section through an alternative embodiment of the composite diaphragm like that of FIG. 1; and

[0028] FIG. 3 shows a composite diaphragm without an insert integrated in its inner part.

SPECIFIC DESCRIPTION OF THE INVENTION

[0029] FIG. 1 shows a composite diaphragm 1 according to the invention mainly formed mainly as a flexible membrane having an outer edge 2 provided with a clamping ring 3 and an annular flexible portion 5 connecting the outer edge 2 to an inner part 4. The inner part 4 in FIGS. 1 and 2 is formed by upper and lower walls 6a and 6b that together form a chamber 7 filled by an insert 8 made of a dimensionally stable material.

[0030] The membrane 4 is a laminate and essentially consists of a layer 9 formed from an elastomer and a layer 10 on the lower face as shown in FIG. 1 or the upper face as shown in FIGS. 2 and 3. A reinforcing core layer 11 shown only in FIG. 1 is also imbedded in the layer 9 and serves to increase the strength of the membrane 4.

[0031] According to the invention, it is now envisaged that the cover layer 10 is formed from an ultrahigh-molecular-weight polyethylene (PE-UHMW). In contrast to previously known solutions, the polytetrafluoroethylene (PTFE) frequently used up to now is thus replaced by the ultrahigh-molecular-weight polyethylene. Like polytetrafluoroethylene, this has a high chemical resistance and is therefore suitable for use with toxic or chemically aggressive media. At the same time, ultrahigh-molecular-weight polyethylene is much easier and more environmentally friendly to recycle.

[0032] FIG. 1 shows that the cover layer 10 is provided on a lower face 12 of the layer 9 turned toward the media being pumped. The layer 9 can be coextruded together with the cover layer 10 to be tightly bonded thereto. In addition, however, it is of course also conceivable to provide the cover layer 10 as a separate overlay film, which is then bonded to the layer 9 by incorporating an adhesion-promoting layer not shown in detail. In this case, it is then also possible to use materials for the layer 9 that would otherwise not be able to form a sufficiently strong bond with the top layer 10 without incorporating an adhesion-promoting layer. In the case of EPDM in particular, however, it is intended that the layer 9 is coextruded together with the outer layer 10.

[0033] An upper face 13 of the membrane 1 not exposed to the medium being pumped is formed by the layer 9. The face 13 has an opening in the inner part 4 through which the insert 8 extends. In addition, the insert 8 has an internal thread 14, via which a membrane piston, not shown in detail, can be connected to the insert 8.

[0034] FIG. 2 shows a further development of the composite diaphragm as shown in FIG. 1, whereby the outer periphery 2 and the clamping ring 3 are formed by a thickened edge. In addition, a large number of ridges 15 are provided in the area of the flexible membrane section 5, which are also shown in FIG. 1, although according to FIG. 2 these ridges 15 form elevations in the cover layer 10. This can further improve the bond strength between the other layer 9 and the cover layer 10.

[0035] The composite diaphragm shown in FIG. 3 has a largely identical design to the composite diaphragms shown in FIGS. 1 and 2, although the inner part 4 now only has a wall 6, which does not form a chamber 7, so that accordingly no insert 8 can be provided inside a corresponding chamber 7.