Patent ID: 8091586

Claim:
A method of manufacturing a venturi tube having a certain fluid flow direction, the method including the steps of: providing a first core member in a mold, the first core member having a periphery and a first end of a certain size, providing a second core member in the mold upstream of the first core member and on a common axis with the first core member, the second core member having a periphery and a first end with a size that is less than the certain size, at least a portion of the first end of the second core member being disposed adjacent to at least a portion of the first end of the first core member such that a substantially 90° step is defined between the first and second core members, the periphery of the first core member tapering outwardly to a second end of the first core member so that the second end of the first core member is sized larger than a second end of the second core member, molding material about the peripheries of the first and second core members such that the peripheries define a stepped fluid flow surface of a venturi tube, and so that any resulting flash occurs only in the certain flow direction, and so that an opening at an exit end of the venturi tube, defined by the second end of the first core member, is sized larger than an opening at an inlet end of the venturi, defined by the second end of the second core member, and removing the first and second core members from the mold.