Drop former for intravenous set

Claim 2

A drop former for use with a drip chamber for determining the flow rate of a parenteral fluid, comprising:, body means defining a parenteral fluid passage therethrough, said parenteral fluid passage having an inlet opening for communicating with a source of parenteral fluid and an outlet opening for communicating with a drip chamber, said parenteral fluid passage defining a drop forming orifice for forming about 12 to 20 drops of parenteral fluid for each millimeter of fluid flowing therethrough at the pressures encountered in intravenous feeding, said outlet opening being at least as large as said inlet opening, and said body means being formed from a plastic which absorbs less than about 0.03 percent by weight water measured over about a twenty-four hour period so that the size of said drops will not materially change with time or flow rate.

Claim 3

The drop former of claim 1 in which said plastic is polyethylene, polypropylene, polytetrafluoroethylene, or fluorinated ethylene propylene.

Claim 4

The drop former of claim 1 in which said plastic is polypropylene.

Claim 5

The drop former of claim 1 in which said inlet opening is formed in a portion of said body means which is of suitable size and shape for insertion into the discharge opening of a parenteral fluid passage in a piercer.

Claim 6

The drop former of claim 1 in which said outlet opening is larger than said inlet opening.

Claim 7

The drop former of claim 1, in which said parenteral fluid passage includes a portion upstream of said drop forming orifice of suitable size for receiving a cannula for forming drops of parenteral fluid which are smaller than said predetermined size.

Claim 8

The drop former of claim 1 in which said parenteral fluid passage includes a frusto-conical section adjacent said inlet opening, a cylindrical section adjacent said outlet opening, and a tapered intermediate section merging into said frusto-conical and cylindrical sections.

Claim 9

The drop former of claim 1 in which said body means comprises a cylindrical base portion forming said outlet opening and a tapered portion attached to said base portion and forming an annular shoulder therewith for facilitating attachment of said drop former to a piercer.

Claim 10

The drop former of claim 8 in which said tapered portion has a ring collar on the external surface thereof for the adhesive attachment of said drop former to said piercer.

Claim 11

The drop former of claim 8 in which said base portion includes an inwardly tapered bottom portion which merges into said outlet opening forming a sharp cylindrical edge therewith.

Claim 12

The drop former of claim 1 in which the ratio of the length of said drop forming orifice to the diameter oF said outlet opening is at least 2:1.

Claim 13

A piercer and flow meter for an intravenous set, comprising: a piercer having a base and a piercing member with a sharp end for piercing the closure of a parenteral fluid container, said piercer defining a parenteral fluid passage for transferring parenteral fluid from said container, said parenteral fluid passage having an opening in said piercing member for communicating with said container and a discharge opening in said base; a drip chamber attached to said piercer and communicating with said discharge opening; and a drop former attached to said piercer and comprising body means defining a parenteral fluid passage therethrough, said parenteral fluid passage having an inlet opening communicating with said discharge opening in said piercer and an outlet opening communicating with said drip chamber, said parenteral fluid passage defining a drop forming orifice for forming drops of parenteral fluid of predetermined size which can be visually observed while falling through said drip chamber for determining the flow rate of said parenteral fluid, said outlet opening being at least as large as said inlet opening, and said body means being formed from a plastic which absorbs less than about 0.03 percent by weight water measured over about a 24 hour period so that the size of said drops will not materially change with time of flow rate.

Claim 14

A piercer and flow meter for an intravenous set, comprising: a piercer having a base and a piercing member with a sharp end for piercing the closure of a parenteral fluid container, said piercer defining a parenteral fluid passage for transferring parenteral fluid from said container, said parenteral fluid passage having an opening in said piercing member for communicating with said container and a discharge opening in said base; a drip chamber attached to said piercer and communicating with said discharge opening; and a drop former attached to said piercer and comprising body means defining a parenteral fluid passage therethrough, said parenteral fluid passage having an inlet opening communicating with said discharge opening in said piercer and an outlet opening communicating with said drip chamber, said parenteral fluid passage defining a drop forming orifice for forming drops of parenteral fluid of predetermined size which can be visually observed while falling through said drip chamber for determining the flow rate of said parenteral fluid, said outlet opening being at least as large as said inlet opening, and said body means being formed from a plastic which absorbs less than about 0.03 percent by weight water measured over about a 24 hour period so that the size of said drops will not materially change with time of flow rate.

Claim 15

The piercer and flow meter of claim 12 in which said plastic is polyethylene, polypropylene, polytetrafluoroethylene, or fluorinated ethylene propylene.

Claim 16

The piercer and flow meter of claim 12 in which said plastic is polypropylene.

Claim 17

The piercer and flow meter of claim 12 in which the outlet opening in said drop former is larger than said inlet opening.

Claim 18

The piercer and flow meter of claim 12 in which the parenteral fluid passage in said drop former includes a portion upstream of said drop forming orifice of suitable size for receiving a cannula for forming drops of parenteral fluid which are smaller than said predetermined size.

Claim 19

The piercer and flow meter of claim 12 in which the parenteral fluid passage of said drop former includes a frusto-conical section adjacent said inlet opening, a cylindrical section adjacent said outlet opening, and a tapered intermediate section merging into said frusto-conical and cylindrical sections.

Claim 20

the piercer and flow meter of claim 12 in which the body means of said drop former comprises a cylindrical base portion forming said outlet opening and a tapered portion attached to said base portion and forming an annular shoulder therewith for facilitating attachment of said drop former to said piercer.

Claim 21

The piercer and flow meter of claim 18 in which the tapered portion of said drop former has a ring collar on the external surface thereof for enabling the adhesive attachment of said drop former to said piercer.

Claim 22

The piercer and flow meter of claim 18 in which the base portion of said drop former includes an inwardly tapered bottom portion which merges into said outlet opening forming a sharp cylindrical edge therewith.

Claim 23

The piercer and flow meter of claim 12 in which the outlet opening of said drop former defines a drop forming orifice for forming drops of parenteral fluid of such predetermined size that from 12 to 20 drops are formed for each milliliter of fluid flowing therethrough.

Claim 24

The piercer and flow meter of claim 12 in which the ratio of the length of said drop forming orifice to the diameter of said outlet opening is at least 2:1.