An eductor for mixing two liquids wherein the eductor includes a closed or non-air gap back flow prevention member. The vacuum profile of the eductor is altered by changing an opening in a passage portion to controllably divert water flow around the venturi tube or diverting the water without the opening. This affords the changing of the vacuum profile without redesigning the entire eductor.
1. An eductor for mixing first and second liquids comprising:
a body member providing a longitudinal axis;
a flow path extending longitudinally through the body member, the flow path defined by a first flow guide and a second flow guide, the first flow guide defined by at least one unapertured wall extending to an end of the flow guide and extending to the second flow guide and having interior surfaces converging toward the second flow guide, the second flow guide constructed and arranged to receive liquid from the first flow guide;
a closed back flow prevention member operatively associated with the first flow guide;
a venturi tube in the flow path for receiving liquid from the second flow guide, the second flow guide and the venturi tube connected by a passage portion;
an opening in the passage portion, the opening constructed and arranged to produce a desired vacuum in the venturi tube; and
at least one channel lateral to the longitudinal axis for flowing a liquid concentrate into the venturi tube; and
the flow path further including a discharge passage extending from the venturi tube to the outside of the body member.
2. The eductor as defined in claim 1 wherein the lateral channel includes a check valve.
3. The eductor as defined in claim 1 wherein there are present two lateral channels.
4. The eductor as defined in claim 1 wherein the back flow prevention member includes a resilient sheath.
5. An eductor for mixing first and second liquids comprising:
a body member providing a longitudinal axis;
a flow path extending longitudinally through the body member, the flow path defined by a first flow guide and a second flow guide, the second flow guide constructed and arranged to receive liquid from the first flow guide;
a closed back flow prevention member operatively associated with the first flow guide;
a venturi tube in the flow path for receiving liquid from the second flow guide, the second flow guide and the venturi tube connected by a passage portion;
an opening in the passage portion through which liquid is directed away from the venturi tube, the second flow guide defined by a tubular portion extending over the opening in the passage portion; and
at least one channel lateral to the longitudinal axis for flowing a liquid concentrate into the venturi tube;
the flow path further including a discharge passage extending from the venturi tube to the outside of the body member; and
wherein the extension of the tubular portion over the opening in the passage portion is designed to afford a desired vacuum profile.
6. The eductor as defined in claim 5 wherein the second flow guide and the tubular portion are is in the form of a funnel member.
7. The eductor as defined in claim 5 wherein the lateral channel includes a check valve.
8. The eductor as defined in claim 5 wherein there are present two lateral channels.
9. The eductor as defined in claim 5 wherein the back flow prevention member includes a resilient sheath.