U.S. patent application number 11/327395 was filed with the patent office on 2006-05-25 for valve for use with a syringe and which prevents backflow.
Invention is credited to Bruce Leigh Kiehne.
Application Number | 20060108555 11/327395 |
Document ID | / |
Family ID | 25634020 |
Filed Date | 2006-05-25 |
United States Patent
Application |
20060108555 |
Kind Code |
A1 |
Kiehne; Bruce Leigh |
May 25, 2006 |
Valve for use with a syringe and which prevents backflow
Abstract
A one-way valve assembly can be fitted to the end of a syringe
to allow fluid to flow from the syringe and into a body cavity but
to prevent backflow. The valve assembly is opened by insertion of
the luer tip of the syringe into the assembly inlet. The valve has
an internal elastic member that forms a variable volume internal
chamber. This chamber expands upon insertion of the luer tip into
the inlet and shrinks when the luer tip is removed from the
assembly. The shrinking action creates a positive pressure in the
valve assembly to prevent backflow.
Inventors: |
Kiehne; Bruce Leigh;
(Springwood, AU) |
Correspondence
Address: |
HOFFMAN WASSON & GITLER, P.C;CRYSTAL CENTER 2, SUITE 522
2461 SOUTH CLARK STREET
ARLINGTON
VA
22202-3843
US
|
Family ID: |
25634020 |
Appl. No.: |
11/327395 |
Filed: |
January 9, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10475530 |
Oct 30, 2003 |
6991215 |
|
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PCT/AU02/00861 |
Jul 1, 2002 |
|
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11327395 |
Jan 9, 2006 |
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Current U.S.
Class: |
251/149.7 |
Current CPC
Class: |
Y10S 604/905 20130101;
A61M 2039/266 20130101; A61M 39/24 20130101; A61M 39/26
20130101 |
Class at
Publication: |
251/149.7 |
International
Class: |
F16K 51/00 20060101
F16K051/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 23, 2001 |
AU |
63598/01 |
Dec 12, 2001 |
AU |
PR9444 |
Claims
1. A valve assembly that comprises an inlet and an outlet, a flow
pathway that extends through the valve assembly from the inlet to
the outlet, a plunger that is positioned in the flow pathway and
which can move between a forward open position where fluid can flow
from the inlet to the outlet, and a retracted closed position where
fluid is prevented from flowing from the inlet to the outlet, the
plunger having a forward portion, an at least partially elastic
sock that has an outer end fixed to the valve assembly, and an
inner portion which engages with the plunger such that
reciprocation of the plunger from the retracted position to the
forward position causes at least part of the sock to stretch, and a
variable volume chamber having walls defined by the plunger and the
sock, the chamber forming part of the flow pathway, the chamber
having smaller or nil volume when the plunger is in the retracted
position, and a larger volume when the plunger is in the extended
position, whereby upon retraction of the plunger, the variable
volume chamber reduces in volume which results in a pumping action
to pump fluid through the fluid pathway towards the outlet, thereby
reducing or preventing backflow.
2. The assembly of claim 1, wherein the valve assembly has an outer
body formed in two parts that are attached together.
3. The assembly of claim 2, wherein one of the two parts comprises
a top part having an outer passageway of smaller diameter or
cross-section, and an inner passageway of larger diameter or
cross-section, the inner passageway forming part of an internal
chamber.
4. The assembly of claim 3, wherein the outer passageway contains
at least one longitudinal slot or recess that comprise fluid
ports.
5. The assembly of claim 3, wherein the other of the two parts
comprises a base part which has an outer passageway of smaller
diameter or cross-section, and an inner passageway of larger
cross-section or diameter and which forms part of the internal
chamber that is also defined by the top part.
6. The assembly of claim 5 that has a fluid flow pathway that
extends through the valve assembly from the inlet to the outlet,
and through the central internal chamber.
7. The assembly of claim 1, wherein the plunger has a fluid flow
pathway extending at least partially therethrough or
therealong.
8. The assembly of claim 7, wherein the plunger has an engagement
means to engage with the elastic sock.
9. The assembly of claim 8, wherein the engagement comprises an
annular step or shoulder portion on the plunger and which catches
against or engages with the elastic sock upon forward movement of
the plunger.
10. The assembly of claim 1, wherein the sock has a substantially
circular base portion, and an extending tubular wall portion.
11. The assembly of claim 10, wherein the wall portion extends
substantially about the forward portion of the plunger.
12. The assembly of claim 11, wherein the base portion has a
peripheral edge that is held against movement in the valve
assembly.
13. The assembly of claim 12, wherein the tubular wall portion is
compressible or is otherwise configured to allow it to be shortened
in length, for instance by allowing the wall portion to buckle in a
controlled manner.
14. The assembly of claim 1, wherein the sock has a substantial
disklike configuration.
15. The assembly of claim 14, wherein the sock has an outer
peripheral edge that is attached to the valve and an internal
opening which is typically a central opening and through which the
forward part of the plunger can pass.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of parent
application Ser. No. 10/475,530, filed Oct. 30, 2003, and presently
pending in Group Art Unit 3754. A Notice of Allowance was mailed on
Aug. 23, 2005, and the issue fee was paid on Nov. 9, 2005.
FIELD OF THE INVENTION
[0002] This invention is directed to a valve that can be attached
to a catheter, a needle or any other type of injecting device and
that has a particular configuration to prevent backflow. The
invention is particularly directed to a needle free access valve
for use in a needle free intravenous access system.
BACKGROUND ART
[0003] A needle free access valve is one where the valve can be
opened using a needleless syringe. A needleless syringe is a
syringe where the needle has been removed such that the front of
the syringe has only the luer taper or luer lock. Such valves are
known but suffer from a number of disadvantages.
[0004] A typical known valve has a body composed of two cylindrical
containers. One container has a tubular opening into which the luer
taper can be pressed. The other container has a tubular opening
filled with a luer lock that allows the valve to be attached to
various medical devices. Fluid flows through the luer taper upon
depression of the syringe plunger and flows through the valve. The
valve has a circular valve disk that can be forced open by the
pressure of the fluid. When the fluid pressure stops, the valve
returns to its closed position. This type of arrangement is
entirely conventional. One disadvantage with this arrangement is
that high levels of fluid flow can often not be obtained due to the
design of the valve. That is, the valve itself is solid and fluid
can flow only about the edge of the valve when the valve is opened.
Another disadvantage is the lack of sterilisation around the inlet
part of the valve.
[0005] A serious disadvantage with many existing one-way valves is
that fluid can flow back into the valve from the body cavity or the
body in which the needle etc has penetrated. This results in
contamination, and a potential health hazard. Most valves are
provided with some form of spring or bias to naturally bias the
valve back into the closed position. Therefore, there would be a
great advantage if it was possible to provide a one-way valve (for
instance a needle free access valve) where there is little or no
likelihood of backflow occurring upon removal or retraction of the
syringe (or other device) to which the valve is attached.
[0006] Other disadvantages with conventional valves are the
production costs, the relatively large number of components making
up the valve, the difficulty in mass production of the valve.
OBJECT OF THE INVENTION
[0007] It is an object of the invention to provide a valve assembly
for use in the medical field and which can reduce or entirely
prevent the occurrence of backflow from the body cavity etc back
into the valve assembly.
[0008] It is further object of the invention to provide a valve
assembly that may at least partially overcome the abovementioned
disadvantages or provide the public with a useful or commercial
choice.
[0009] In one form, the invention resides in a valve assembly that
comprises: [0010] 1. An inlet and an outlet, [0011] 2. A flow
pathway that extends through the valve assembly from the inlet to
the outlet, [0012] 3. A plunger that is positioned in the flow
pathway and which can move between a forward open position where
fluid can flow from the inlet to the outlet, and a retracted closed
position where fluid is prevented from flowing from the inlet to
the outlet, the plunger having a forward portion, [0013] 4. An at
least partially elastic sock that has an outer end fixed to the
valve assembly, and an inner portion which engages with the plunger
such that reciprocation of the plunger from the retracted position
to the forward position causes at least part of the sock to
stretch, and [0014] 5. A variable volume chamber having walls
defined by the plunger and the sock, the chamber forming part of
the flow pathway, the chamber having smaller or nil volume when the
plunger is in the retracted position, and a larger volume when the
plunger is in the extended position, whereby upon retraction of the
plunger, the variable volume chamber reduces in volume which
results in a pumping action to pump fluid through the fluid pathway
towards the outlet, thereby reducing or preventing backflow.
[0015] With this arrangement, the apparatus can be attached to a
syringe (or other device), and a needle, catheter or other
body-injecting device can be attached to the apparatus. The
contents of the syringe can then be passed through the apparatus
and into the body by depressing the plunger into the forward (open)
position. As the plunger moves towards the forward position, it
stretches at least part of the sock and the variable volume chamber
adopts the larger volume. However once the syringe is removed, or
retracted, the sock retracts to its initial position, causing the
plunger to be pushed back into the closed position and at the same
time contracting the variable volume chamber. The contraction
causes a positive pressure inside the apparatus that means that
backflow does not occur. Indeed, it is found that the positive
pressure is sufficient to at least partially "pump" any residual
fluid in the apparatus through the outlet upon retraction of the
plunger. This is in contrast to known devices where retraction of
the plunger or closure of the valve often allows backflow of fluid
through the outlet and into the valve apparatus.
[0016] The valve assembly may have an outer body formed in two
parts that are attached together. The two parts may comprise a top
part, and a base part. The top part is substantially hollow and
suitably contains an outer passageway of smaller diameter or
cross-section, and an inner passageway of larger diameter or
cross-section, the inner passageway forming part of an internal
chamber. The outer passageway may contain longitudinal slots or
recesses that comprise fluid ports the reason for which will be
described in greater detail below.
[0017] The base part may be substantially hollow and may contain a
outer passageway of smaller diameter or cross-section, and an inner
passageway of larger cross-section or diameter and which forms part
of the internal chamber that is also defined by the top part. Thus,
when the two parts are attached, there is provided a substantially
central internal chamber. The outer passageway of the base part may
be surrounded by attachments to allow the outlet to attach to a
needle etc.
[0018] The apparatus has a flow pathway that extends through the
valve assembly from the inlet to the outlet, and typically through
the central internal chamber described above.
[0019] The apparatus has a plunger. The plunger is moveable between
a forward open position where the plunger moves more towards the
outlet, and a retracted closed position where the plunger is more
towards the inlet. The plunger typically slides or reciprocates
between the two positions.
[0020] The plunger has a forward portion which is typically a
projecting nose portion. Suitably, the plunger also has a rear body
portion. The nose portion and the body portion may be formed
integrally. The plunger suitably has a fluid flow pathway extending
at least partially therethrough. The fluid flow pathway may
comprise an internal flow passageway extending through the nose
portion which means that the nose portion may have an open outer
end. Suitably, the internal flow passageway includes a transverse
through bore in the rear body portion such that fluid can pass
through the through bore and through the flow passageway that
extends through the nose portion.
[0021] The rear body portion of the plunger is typically configured
and dimensioned to substantially fill the outer passageway in the
top part of the valve assembly. Suitably, the rear body portion has
an end face that is substantially flush with the end of the top
part of the valve assembly that can make cleaning of this area
quite easy. The rear body portion typically has a sealing face
extending about the rear body adjacent the end face and which seals
with the internal wall of the outer passageway.
[0022] The plunger may an engagement means to engage with the
elastic sock. The engagement means may comprise an annular step or
shoulder portion on the plunger and which can catch against or
engage with the elastic sock upon forward movement of the plunger.
Alternatively, the plunger can push against the sock.
[0023] The apparatus has an at least partially elastic sock. The
sock may be formed of a rubbery elastic material having a good
memory. In one form of the invention, the sock may be formed as a
separate component. The elastic sock may comprise a substantially
circular base portion, and an extending tubular wall portion. The
base portion and the wall portion may be formed integrally. The
wall portion may extend substantially about the nose portion of the
plunger. The base portion may have a peripheral edge that is held
against movement in the valve assembly. Suitably, the peripheral
edge also comprises a sealing edge. Preferably, the base portion is
elastic and can therefore be stretched upon forward movement of the
plunger. Preferably, the tubular wall portion is compressible or is
otherwise configured to allow it to be shortened in length, for
instance by allowing the wall portion to buckle in a controlled
manner. The wall portion may be provided with circumferential
recesses that provide zones to allow a controlled buckling of the
wall portion. The end of the tubular wall portion may be provided
with a sealing lip or a sealing bead that seals against the base
portion of the valve assembly.
[0024] Alternatively, the sock may have a substantial disklike
configuration without a tubular wall portion. In this embodiment,
the sock may have an outer peripheral edge that is attached to the
valve assembly in a manner similar to that described above. The
sock may have an internal opening, which is typically a central
opening and through which part of the plunger can pass, which is
typically a nose portion of the plunger. If desired, the plunger
may be provided with an annular recess to capture the wall of the
internal opening. With this arrangement, the plunger may be
provided with seals.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Embodiments of the invention will be described with
reference to the following drawings in which:
[0026] FIG. 1. Illustrates an exploded section view of the various
components of the valve apparatus.
[0027] FIG. 2. Illustrates the valve in the closed position with
the plunger in the retracted position.
[0028] FIG. 3. Illustrates the valve in the partially open position
with the plunger moving to the forward position.
[0029] FIG. 4. Illustrates the valve in the fully open
position.
[0030] FIG. 5. Illustrates a second embodiment of the invention
having a slightly different sock arrangement that does not contain
a tubular portion.
[0031] FIG. 6. Illustrates the valve assembly of FIG. 5 with the
plunger in the retracted closed position and the sock in a
substantially unstretched mode.
[0032] FIG. 7. Illustrates the valve assembly of FIG. 6 with the
plunger has been pushed into the forward open position and the
elastic sock is stretched.
[0033] FIG. 8. Illustrates a third embodiment of the invention with
the plunger in the closed position.
[0034] FIG. 9. Illustrates the invention of FIG. 8 in the open
position.
BEST MODE
[0035] Referring to the drawings, and initially to FIG. 1, there is
illustrated a valve assembly which comprises an inlet 10 and an
outlet 11, a flow pathway that extends through the valve assembly
from inlet 10 to outlet 11, a plunger 12 that is positioned in the
flow pathway and which can reciprocate between a forward open
position illustrated in FIG. 3, and a retracted closed position
illustrated in FIG. 2, the plunger having an elongate forward nose
portion 13, an elastic sock 14 which is adapted to extend at least
partially about the nose portion 13 of plunger 12, engagement means
15 to engage the plunger to the sock, and a variable volume chamber
16 best illustrated in FIG. 3 (where the chamber is of maximum
volume), but also just visible in FIG. 2 (where the chamber is of
minimal and almost having a zero volume).
[0036] Referring to the parts in greater detail, the valve assembly
in the embodiment comprises an outer body that is formed of two
parts that are attached together, the two parts being a top part 17
and a base part 18. These parts are formed of plastic material and
are joined together by any suitable method. Top part 17 is best
illustrated in FIG. 1 and is substantially hollow. Top part 17
comprises an outer passageway 19 which is circular and which has a
smaller diameter, and an inner passageway 20 which is also circular
and which has a substantially larger diameter. Similarly, base part
18 has an inner passageway 21 that has a substantially larger
diameter than outer passageway 22. When the two parts are joined as
illustrated in FIG. 2 and FIG. 3, the two larger diameter
passageways together form an internal chamber 23. Outer passageway
22 terminates in outlet 11, while outer passageway 19 terminates in
inlet 10.
[0037] The outer passageway 19 in top part 17 contains a plurality
of longitudinal open ended fluid ports 24. Ports 24 comprise
recesses in the wall of outer passageway 19 and are open ended
which means that the ports communicate with chamber 16. The ports
24 do not extend entirely along the wall of passageway 19. Rather,
the ports terminate partway along the wall such that a smooth wall
portion 25 extends between the end of ports 24 and inlet 10. The
reason for this will be described in greater detail below.
[0038] Base part 18 contains a standard luer lock fitting 26 which
extends about passageway 22 and which functions to allow a needle
etc to be attached to this part of the assembly. Of course, other
types of attachments can also be used.
[0039] Inner passageway 21 has a diameter that is smaller than
inner passageway 20. Thus, the wall 27 of inner passageway 21
passes into inner passageway 20 this being best illustrated in FIG.
2. Moreover, wall 27 has a length that results in the wall 27 being
spaced somewhat from wall 28 of top part 17 (see FIG. 2). This
spacing facilitates the attachment of the elastic sock that will be
described in greater detail below.
[0040] Plunger 12 is formed of plastic material and comprises a
unitary body. The plunger has a particular configuration that
provides a nose portion 13, and a rear body portion 29. Nose
portion 13 is slightly tapered and has a through passageway 30
which passes through an open outer end 31 and functions to allow
fluid to flow through the valve assembly. Body portion 29 is
provided with a transverse through bore 32 through which fluid can
pass. Body portion 29 has a substantially cylindrical outer wall
provided with a sealing area or collar 35. This is why the fluid
ports 24 in end wall 25 terminate short of inlet 10 to also provide
a smooth area which functions as a sealing zone 36. Thus, when the
plunger is in the closed position illustrated in FIG. 2, the
sealing collar 35 seals against the sealing zone 36 to provide seal
against fluid flow.
[0041] When plunger 12 is pushed forwardly from the position
illustrated in FIG. 2 to the position illustrated in FIG. 3 and 4,
the plunger only moves by a few mm, but this movement is sufficient
to move collar 35 away from sealing zone 36 and into the area of
the flow ports 24 and to allow fluid to pass along the outside wall
of body portion 29, through the fluid ports 24, through bore 32
through passageway 30 and through outlet 11. Conversely, when the
plunger is retracted from the position illustrated in FIG. 3 to the
position illustrated in FIG. 2 the plunger again seals against
passage of fluid from inlet 10 through outlet 11.
[0042] Fluid only flows when the flow ports 24 are opened by collar
35 moving past the outer most edge of the flow ports. At all other
times a seal is maintained between the internal wall 25 and collar
35.
[0043] The plunger is biased back to its retracted position by the
elastic sock 14 which also provide additional functions. Elastic
sock 14 is made of a rubbery elastic material having an excellent
memory. The elastic sock has a circular base portion 39 and an
extending tubular wall portion 40. The elastic sock, when in the
rest position, adopts the configuration illustrated in FIG. 1. The
base portion is made of a stretchable and elastic material. The
base portion has a peripheral edge 41 that is thickened with
respect to the thickness of the base portion immediately next to
the peripheral edge.
[0044] FIG. 2 illustrates attachment of the sock to the apparatus
and shows how the thickened peripheral edge 41 is trapped between
wall 27 of base part 18 and the inner wall of top part 17. The area
of the base part between the peripheral edge and the tubular wall
portion 40 is quite elastic and can stretch. Peripheral edge 41
also functions to seal the fluid pathway in the apparatus. The
outer end of tubular wall portion 40 is provided with an annular
sealing lip 45 that fits within an annular recess 46 formed in base
part 18 (see FIG. 2).
[0045] The plunger 12 has an engagement means 15 that comprises an
annular shoulder extending from the base of nose portion 13. The
annular shoulder sits behind base portion 39, this being best
illustrated in FIG. 2. Thus, when the plunger 12 is pushed
forwardly from the position illustrated in FIG. 2 to the position
illustrated in FIG. 3, the engagement means 15 will push base
portion 39 forwardly. As the peripheral edge 41 is trapped in
place, the base portion will begin to stretch this being best
illustrated in FIG. 3. As this occurs, a chamber 16 (called the
variable volume chamber) opens up from a very small or zero volume
best illustrated in FIG. 2, to a larger volume best illustrated in
FIGS. 3 and 4. This chamber 16 forms part of the fluid flow pathway
that means that fluid fills or can at least partially fill chamber
16. Of course, upon removal of the syringe tip (which pushes the
plunger forwardly) from the apparatus, the plunger is pulled back
into the retracted position by virtue of the stretched base portion
39 shrinking back to its rest position. This action reduces the
volume of chamber 16 and causes any fluid in the chamber to be
"pumped" or squeezed through flow passageway 30 and through outlet
11.
[0046] The sock is designed such that when the plunger 12 is in the
retracted closed position, there is still some tension in the sock
to keep the plunger in the retracted position.
[0047] The tubular wall portion 40 of the sock has an array of
spaced circumferential grooves 43 which are best illustrated in
FIG. 1 and FIG. 2. These grooves facilitate a control buckling of
the tubular wall portion 40 from a substantially unbuckled position
illustrated in FIG. 2, to a buckled position illustrated in FIG. 3.
The buckling compensates for the stretching of base portion 39. The
tubular wall portion (also called the sock stem) has a natural
position and memory to retain the position illustrated in FIG. 2.
Thus, when the wall portion adopts the buckled position illustrated
in FIG. 3, it also assists in pushing back to the plunger as soon
as the syringe (or other type of device) is removed from inlet
10.
[0048] Referring to FIG. 4, when the plunger 12 is in the fully
open position, the plunger nose seals against annular sealing lip
45.
[0049] FIGS. 5-7 illustrate another embodiment of the invention,
the primary difference being the configuration of the elastic sock
on the plunger. Like parts have been given like numbers.
[0050] In this embodiment, plunger 47 is substantially similar to
the plunger described above except that the nose portion 48
contains a O ring seal 49 which is in sliding engagement with the
inside wall of outer passageway 22 thereby preventing fluid from
flowing along the outside wall of the nose portion 48. The plunger
supports an elastic sock 51 that is disklike in configuration, and
differs from the elastic sock described above in that there is no
tubular portion. The sock 51 again has an outer peripheral
thickened sealing edge 52 that is trapped in the valve housing as
illustrated in FIG. 6 and FIG. 7.
[0051] As plunger 47 moves from its retracted position illustrated
in FIG. 6 to the extended position illustrated in FIG. 7, the
movement causes the elastic sock 51 to stretch. This stretching
action increases the volume of the variable volume chamber 16. When
the syringe tip (not illustrated) or other similar device is
removed from inlet 10, plunger 47 will then be retracted back to
the closed position illustrated in FIG. 6 by virtue of the bias
provided by the stretched sock. Additionally, shrinking of the sock
back to its initial position will reduce the volume of chamber 16
that provides the positive pressure to prevent backflow. A further
O ring 55 is positioned on the outer edge of plunger 47.
[0052] In each embodiment, a small air passageway 56 is provided to
allow air to pass into chamber 23 upon shrinking of the sock and to
allow air to pass out of chamber 23 upon stretching of the
sock.
[0053] The valve assembly prevents back flow of fluids by
maintaining a positive pressure in chamber 16.
[0054] Referring to FIGS. 8 and 9 there is illustrated an
anti-siphon means that can be fitted to a valve assembly which is
described in Australian patent 736326 the specification of which is
incorporated herein by cross reference. In this embodiment, the
anti-siphon means includes a sleeve 64 which fits generally in a
bottom casing 69 which is one part of a two part housing. Sleeve 64
can be formed from an elastic material or a material that is
elastic in the region where the sleeve contacts opening fingers 74.
Suitably, the sleeve is formed from SANTOPRENE or similar material.
Sleeve 64 has an inner portion which is dish shaped 75 and an outer
portion 69 which is in the shape of a tube and which extends along
the inside wall of spigot 71, and terminates in a small lip 72
which extends over the front end of spigot 71 to hold the sleeve in
place. Inner portion 75 of the sleeve is sealed to the innermost
annular land portion 65 of bottom casing 69. Thus, the sleeve can
be positioned in bottom casing 69 prior to bottom casing 69 being
attached to top casing 62. A small annular thickened portion 66 is
provided on the sleeve where the dish shaped portion 75 joins or
becomes part of the outer portion 69. Suitably, the entire sleeve
is formed from a single piece of material.
[0055] The sleeve is designed to naturally adopt a position
illustrated in FIG. 8 where it abuts against, or is closely spaced
from fingers 74. In this position, the sleeve isolates the fluid
pathway from the remainder of chamber 67. When valve member 61 is
pushed forwardly, the arrangement adopts the position illustrated
in FIG. 9. As valve member is pushed forwardly, it deforms or
pushes apart fingers 74. Fingers 74 in turn push back/stretch
sleeve 64 into chamber 67. This action causes air in chamber 67 to
be vented from the chamber through a small vent opening 68. Vent 68
in the particular embodiment illustrated in FIG. 8 and FIG. 9
extends between chamber 67 and outlet 73. Specifically, vent 68
passes between chamber 67 and the threads 70 in the internal
passageway. An advantage in having the vent in this position is
that it cannot be clogged by any cleaning/wiping of the exterior of
the valve assembly. Of course, it is possible for vent 68 to vent
air from chamber 67 to any convenient outer part of the valve
assembly.
[0056] When valve member [plunger] 61 is pushed forwardly, fluid
can now pass from inlet 60 through outlet 73. When valve member 61
is pushed back from the position illustrated in FIG. 9 to the
position illustrated in FIG. 8, the stretched sleeve 64 will shrink
back to the position illustrated in FIG. 8, and will stay abutting
against or closely spaced from the fingers 74/valve member 61. As
this occurs, air will pass through vent 68 and into chamber 67 to
equalise the pressure. Thus, air will pass through vent 76 and not
through outlet 16. The effect of this is that as valve member 61 is
retracted, fluid will not suck back through outlet 73 as air will
move preferentially into chamber 67 through vent 68. The reason for
this is that outlet 73 will usually be connected to some form of
needle assembly or body access means and it is much more difficult
to suck fluid back through outlet 73 then to have air passing
through vent 68. Thus, the arrangement functions as an anti-siphon
means to prevent body fluid (for instance blood) from being sucked
back into the valve assembly.
[0057] Another advantage with the arrangement is that possibly
contaminated air is kept separate from the fluid flow pathway of
the valve assembly by virtue of the sleeve 64.
[0058] It should be appreciated that various other changes and
modifications can be made to the invention without departing from
the spirit and scope of the invention.
* * * * *