Tapping valve with a plastic valve housing for shipping and storage tanks for liquids

A tapping valve with a plastic valve housing for shipping and storage tanks for liquids, which are equipped with an inner tank with a filling socket and a drain socket for connecting the tapping valve, an outer jacket of a metal cage or sheet metal, and a pallet-like metal support frame. The tapping valve is screwed by means of the inlet socket of the valve housing onto a connecting flange, which is designed as a threaded flange, is made of an electrically conductive plastic material, and is welded onto the drain socket of the inner tank. The connecting flange of the valve housing is connected with the support frame or the outer jacket of the shipping and storage tank by an electric grounding conductor.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a tapping valve with a plastic valve housing, especially a flap valve or ball valve, for shipping and storage tanks for liquids, which are equipped with a plastic inner tank with a closable filling socket and a drain socket for connecting the tapping valve, an outer jacket that consists of a metal cage or sheet metal, and a pallet-like support frame made of metal or an at least partially electrically conductive plastic for supporting the inner tank.

2. Description of the Related Art

In a shipping and storage tank for liquids that is described in DE 198 15 082 A1, a grounding part is installed in the tapping valve of the general type in question, which is mounted on the outlet socket of the inner tank. The grounding part is designed as a bent metal sheet or small metal plate, which extends over a section of the inside borehole of the tapping valve and is attached by a fastening screw and a grounding cable to the support frame of the tank.

This tapping valve has the following disadvantages:

The fastening screw, which is screwed through the wall of the valve housing and is necessary for mounting the metal sheet or small metal plate in the plastic valve housing, does not guarantee the tightness of the valve. The use of metal parts is not allowed in shipping and storage tanks for certain liquid foods. Therefore, tanks equipped with this valve cannot be used to hold these kinds of liquid foods. Finally, when aggressive liquids are shipped or stored in previously known liquid tanks, there is the danger that the grounding part will be damaged in such a way that the electrical grounding will no longer be able to function properly.

Moreover, tapping valves for liquid tanks are known which have a housing that has been provided with antistatic properties. Tapping valves of this type are too expensive for bulk products.

SUMMARY OF THE INVENTION

Therefore it is the object of the invention to further develop the tapping valve of the general type described above for shipping and storage tanks with respect to safe and complete grounding to carry away the electric charges that form as a result of fluid friction during the filling of the tank with liquids and during the tapping of liquids, and with respect to inexpensive manufacture.

In accordance with the invention, this object is met by a tapping valve for shipping and storage tanks for liquids, especially a flap valve or ball valve, for shipping and storage tanks for liquids, which are equipped with a plastic inner tank with a closable filling socket and a drain socket for connecting the tapping valve, an outer jacket composed of a metal cage or sheet metal, and a pallet-like support frame of metal or an at least partially electrically conductive plastic for supporting the inner tank. A connecting flange, which is designed as a threaded flange and is completely or partially produced from electrically conductive plastic material; onto which the valve housing is screwed with the inlet socket; and with which the valve housing is welded onto the drain socket of the inner tank. Electrical grounding of the tapping valve is provided by a grounding conductor, which connects the connecting flange of the valve housing with the support frame or the outer jacket of the shipping and storage tank.

The tapping valve of the invention has a housing that is furnished with a connecting flange made of an electrically conductive plastic for welding the housing onto the drain socket of the plastic inner tank of a liquid shipping and storage tank that is equipped with an outer jacket that consists of a metal cage or sheet metal and with a pallet-like support frame that is made of an electrically conductive material. This tapping valve allows safe electrical grounding of the liquid draining during the emptying of the inner tank by an electric grounding conductor, which connects the connecting flange with the pallet-like support frame or the outer jacket. The tapping valve with the connecting flange made of electrically conductive plastic is much less expensive than the prior-art tapping valve, whose entire plastic housing has been provided with antistatic properties.

DETAILED DESCRIPTION OF THE INVENTION

The shipping and storage tank1for liquids that is shown inFIG. 1, which can be used as a disposable or reusable tank, has as its principal components (1) a replaceable rectangular-solid plastic inner tank2with a front wall3, a rear wall4, and two sidewalls5,6, with a lower base7designed as a drain base and an upper base8, with a filling socket9that is formed on the upper base8and can be closed with a cap10, and with a drain socket12, which is formed on a dome-shaped recess11in the lower section of the front wall3of the inner tank2, is produced as a single part with the inner tank2by blow molding, and serves to mount a tapping valve13, especially a flap valve or a ball valve; (2) an outer jacket14in the form of a cage, which consists of intersecting horizontal and vertical metal cage bars15,16, for holding the inner tank2; and (3) a pallet-like support frame17with standard European dimensions of length and width for supporting the plastic tank2.

The injection-molded high-density polyethylene (HDPE) valve housing18of the tapping valve13is screwed onto a connecting flange21, which has an external thread22, with the inlet socket20, which has a corresponding internal thread19, and is sealed against it, and the connecting flange21, together with the tapping valve13screwed onto it, is mounted on the drain socket12of the inner tank2, preferably by butt welding with heat reflectors. The connecting flange21is manufactured as an injection-molded part from an electrically conductive plastic, for example, polyethylene with carbon or nanoparticles (FIG. 2).

The tapping valve13is equipped with an electric grounding by a grounding conductor23, which connects the connecting flange21of the valve housing18with the trough like base24of the metallic support frame17(FIG. 3).

A tongue25injected-molded on the flange ring30of the connecting flange21is used to fasten the grounding conductor23to the flange ring30(FIG. 4). The tongue25is freely accessible in the mounted state of the tapping valve13.

FIGS. 5 to 9show various means of fastening the grounding conductor23, which is realized as an electric cable26, to the tongue25on the flange ring30of the connecting flange21.

According toFIG. 5, the end26aof the electric grounding cable26has a ring terminal27, by which it is screwed onto the fastening tongue25of the connecting flange illustrated inFIG. 4.

FIGS. 6aand 6billustrate the clipping of the ring terminal27of the grounding cable26onto a mushroom-shaped pin28of the fastening tongue25on the flange ring30of the connecting flange21.

In the fastening means illustrated inFIGS. 7aand 7b, the fastening tongue25of the connecting flange21is divided into two sections25a,25bby a predetermined bending point29. The section25aadjacent to the flange ring30of the connecting flange21has a mushroom-shaped pin28, and the free section25bhas a fastening hole31. To fasten the end26aof the grounding cable26, its ring terminal27is placed on the pin28on the section25aof the fastening tongue25, and the free section25bof the tongue25is bent over and clipped onto the pin28, so that the ring terminal27of the cable26is clamped between the two tongue sections25a,25bof the tongue25of the connecting flange21.

FIGS. 8aand 8billustrate another type of fastening, in which the ring terminal27at one end26aof the grounding cable26is placed on a smooth pin32on the tongue25on the flange ring30of the connecting flange21, and the end32aof the pin that projects beyond the ring terminal27is fused and deformed into a rivet head32b.

In the possible fastening means shown inFIG. 9, the pin33on the fastening tongue25of the connecting flange21has a drill hole34for a plug35mounted on one end26aof the grounding cable26.

According toFIG. 10, the other end26bof the grounding cable26can be bolted on the sheet-metal base24of the support frame17by means of a ring terminal27mounted on the grounding cable26. It is also possible to fasten the grounding cable26on the sheet-metal base24of the support frame17by the fastening means illustrated inFIGS. 6a, 6b;7a,7b;8a,8b; and9.

In addition, it is possible to fasten the end26bof the grounding cable26to the outer cage14of the shipping and storage tanks.

FIGS. 11aand 11billustrate the realization of the grounding conductor23as an electrically conductive strip element36made of plastic or metal. As shown inFIG. 11a, one end36aof the strip element36can be welded or adhesively bonded to the tongue25on the flange ring30of the connecting flange21of the tapping valve13. In addition, it is possible to attach the strip element36to the tongue25of the connecting flange21by riveting, bolting or clinching.

In the type of fastening shown inFIG. 11b, the end36aof the strip element36has a bracket37by which it can be mounted on the tongue25on the flange ring30of the connecting flange21.

In another embodiment of the tapping valve13, the part of the connecting flange21that comes into contact with the liquid running out of the shipping and storage tank1during the operation of emptying the tank is made of a plastic with an electrically conductive additive, while the remaining part of the connecting flange is made of pure plastic. The manufacturing costs of the tapping valve of the shipping and storage tank are reduced by a connecting flange of this type.