A multi-way cock comprises a housing including a cylinder having a plurality of branch tubes extending from the periphery thereof, and a plug including a barrel adapted to be rotatably fitted in the cylinder and having a corresponding plurality of channels formed therein, the channels corresponding to the branch tubes in assembled condition. The barrel is formed of a polyester elastomer.

This invention relates to multi-way cocks, typically three-way cocks for 
changing over flow paths of fluids such as blood and medicament fluid. 
BACKGROUND OF THE INVENTION 
In the medical field, multi-way cocks, typically three-way cocks are widely 
used for various purposes including transfusion of blood and infusion of 
fluid medicaments such as glucose fluid and physiological saline to 
patients. Infusion systems often use a plurality of fluid medicaments 
which should be kept separate until infusion. A three-way cock involved in 
the system is manipulated such that selected fluid medicaments may be 
either separately or simultaneously infused into the patient. Also in 
blood transfusion systems, three-way cocks are often useful in introducing 
a desired medicament into transfusing blood or in alternating blood 
transfusion and fluid infusion. 
In general, the three-way cocks are composed of a housing including a 
cylinder having three T-shaped branch tubes extending from the periphery 
thereof. A plug is combined with the housing, which includes a barrel 
adapted to be rotatably fitted in the cylinder and having three T-shaped 
channels corresponding to the branch tubes. A manual lever is attached to 
the top of the plug barrel for rotating the plug in the cylinder. By 
manipulating the lever, the plug can be rotated over an angle of 180 
degrees with respect to the housing. When the lever is at one of angular 
positions, two of the three branch tubes are selectively brought in fluid 
communication through corresponding channels in the plug barrel while the 
remaining branch tube is shut off from communication. The cock assembly in 
which the plug is snugly fitted in the housing is required to be highly 
tight against fluid under pressure and durable in that such high fluid 
tightness is maintained over a number of plug changeovers (for example, 
200 cycles of back-and-forth rotation). 
Conventional three-way cocks generally have housings formed of rigid resin 
materials such as polycarbonate. For the plug, more particularly its 
barrel, high density polyethylene is often used because of biological 
compatibility, workability, and low cost. With this combination, however, 
the housing material is rather less compatible with the plug material, and 
the plug barrel is susceptible to failure as by scraping and abrasion when 
the plug is fitted in the housing or when the plug is rotated during 
service. Such failure often occurs at or near the edge of the openings 
that the channels define at the outer surface of the barrel. 
In recent years, the development of three-way cocks accommodating an 
increased flow rate is desired in order to accelerate blood and fluid 
infusion processes. To this end, the channels in the plug barrel should be 
enlarged to a larger diameter than the currently used one. If the channel 
diameter, that is, the diameter of the opening that the channel defines at 
the barrel outer surface is increased, the circumference of the opening is 
accordingly increased, resulting in increased chances of failure. Since 
the three-way cock is designed such that a pressure resistant fluid tight 
seal is established by close engagement of the housing cylinder's inner 
surface with the plug barrel's outer surface in assembled condition, a 
failure will leave a gap in the engagement, resulting in a loss of fluid 
tight seal. In addition, if chips or fragments are produced by chipping or 
scraping, such fragments can be conveyed into the blood or fluid to be 
infused, imposing potential damage to the patient. The use of such 
three-way cocks is not recommended in the medical field. 
Therefore, an object of the present invention is to provide a novel and 
improved multi-way cock in which the plug barrel can be formed with larger 
diameter channels than in the prior art and is fully resistant to damage 
as by scraping and abrasion upon insertion of the plug into the housing or 
during the heavy duty service. 
SUMMARY OF THE INVENTION 
Investigating the material of which the plug is formed, the inventors have 
found that polyester elastomers are advantageous in that the plug barrel 
formed thereof is not susceptible to damage by scraping and abrasion 
particularly at or near the edge of the opening the channels define at the 
barrel outer surface even when the channels are formed to an increased 
diameter as compared with conventional ones. 
The present invention is directed to a multi-way cock comprising a housing 
including a cylindrical portion having a plurality of branch tubes 
extending from the outer periphery thereof; and a plug including a barrel 
adapted to be rotatably fitted in the cylindrical portion and having a 
corresponding plurality of channels formed therein, the channels 
corresponding to the branch tubes in assembled condition. According to the 
feature of the invention, the barrel is formed of a polyester elastomer. 
Preferably, the polyester elastomer has a modulus in flexure of at least 
800 kgf/cm.sup.2. The polyester elastomer is typically a polyether 
polyester elastomer which has a structure of the formula: 
##STR1## 
wherein n is a number of from 1 to 50, m is a number of from 1 to 5, p is 
a number of from 1 to 8, q is a number of from 1 to 8, and x is a number 
of from 5 to 50. In turn, the housing is formed of a rigid resin. 
The openings that the channels define at the outer periphery of the barrel 
can have a diameter of 1.5 to 5 mm. The plug includes a lever for turning 
the plug in the housing, and the outer surface of the lever is entirely or 
partially coated with a resin which is visually different from the 
barrel-forming elastomer. 
The cock is typically a two or three-way cock and often used in the medical 
field.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring to FIGS. 1 through 4, there is illustrated a multi-way cock 
according to one embodiment of the present invention. More particularly, a 
three way cock is illustrated in FIG. 1 as a typical example with its 
components disassembled. The cock in full assembly is illustrated in FIG. 
4. The multi-way cock generally designated at 1 comprises a housing 2, a 
plug 5, and a lid 10. 
The housing or holder 2 includes a hollow cylindrical portion 3 defining a 
bore 31 therein. The cylindrical portion 3 typically has an inner diameter 
of about 5 to about 8 mm and a wall thickness of about 1 to about 1.5 mm 
although these dimensions are not critical. Three branches 4a, 4b and 4c 
are spaced 90 degrees around the outer periphery and extended radially 
outward from the outer periphery of the cylindrical portion 3. The 
branches 4a and 4c are on a straight line and the branch 4b intersects the 
line at right angles in the illustrated embodiment. Preferably, the 
branches 4a, 4b and 4c are integrally formed with the cylindrical portion 
3. The branches 4a, 4b and 4c define channels 40a, 40b and 40c therein, 
respectively, which communicate with the bore 31. The branches 4a, 4b and 
4c typically have an inner diameter of about 1.5 to about 3.0 mm although 
the inner diameter is not critical. The cylindrical portion 3 further has 
a stationary restrainer 32 which is an arcuate segment extending axially 
upward from the upper edge of cylindrical portion 3. 
The plug 5 includes a barrel 6, a lever support 8, and a lever 9 as shown 
in FIGS. 1 to 3. The barrel 6 is either a solid or hollow cylinder (solid 
in FIG. 1, but hollow in FIG. 3) and adapted to be rotatably fitted in the 
bore 31 of cylindrical portion 3 in a fluid seal manner. Prior to 
assembly, the plug barrel 6 preferably has an outer diameter which is 
approximately 2 to 5% larger than the inner diameter of the cylindrical 
portion 3. The barrel 6 should have a smooth outer surface 60, typically 
with a surface roughness (Rmax) of about 0.001 mm or less. 
In the barrel 6, three channels 7a, 7b and 7c are defined in a T shape in 
correspondence with the channels 40a, 40b and 40c in the branches, 
respectively. Three channels 7a, 7b and 7c are spaced 90 degrees and 
extended radially from the axis of the barrel 6 so that they join together 
for fluid communication at the barrel center. The channels 7a and 7c are 
on a straight line and the channel 7b intersects the line at right angles 
in the illustrated embodiment. The channels 7a, 7b and 7c are also located 
at an axial height such that they mate with the channels 40a, 40b and 40c 
in the branches, respectively, when the plug 5 is fitted in the housing 2, 
that is, in the assembled cock. 
The channels 7a-7c open at the barrel outer surface 60 to define circular 
openings 70a-70c. The openings 70a-70c (channels 7a-7c) typically have a 
diameter of about 1.5 to about 2.0 mm as in the conventional three-way 
cock design, but may have a larger diameter of about 2 to about 5 mm, 
especially 2.0 to 3.0 mm although the diameter is not critical. According 
to the invention, the barrel 6 is formed of a polyester elastomer, as will 
be described later in detail, which withstands chipping as by abrasion 
even when the openings 70a-70c have a larger diameter of about 2 to about 
5 mm. Typically, the diameter of openings 70a-70c is substantially equal 
to that of channels 7a-7c. The larger the diameter of openings 70a-70c, 
the greater becomes the flow rate. Further, the openings 70a-70c most 
often have an equal diameter although they may have different diameters. 
Preferably, the edge of the openings 70a-70c is chamfered for enhanced 
protection of the edge and surrounding portion against chipping. 
On top of the barrel 6 is provided, preferably integrally formed, the lever 
support 8 of generally cylindrical shape having a somewhat larger diameter 
than the barrel. The lever support 8 is adapted to be exposed above the 
assembled cock. 
The support 8 at a lower end has a rotating restrainer 81 which is an 
arcuate segment extending axially downward from the outer wall of the 
support 8. In the assembled cock, as the plug 5 is rotated relative to the 
housing 2, the rotating restrainer 81 on support 8 engages the stationary 
restrainer 32 on cylindrical portion 3 to restrain rotation of the plug 5 
within a predetermined angular range. Assume that the included angles of 
the stationary restrainer 32 and rotating restrainer 81 sum to 180.degree. 
C., the plug 5 is allowed for rotation over an angle of 360.degree. C. 
minus 180.degree. C., that is, 180.degree. C. It will be understood that 
the stationary restrainer 32 and rotating restrainer 81 are not essential 
to the invention. The plug 5 is allowed for free rotation over 360 degrees 
if any restraint means is absent. 
The lever 9 extends from the lever support 8 in an opposite direction to 
the barrel channel 7b. Preferably the lever 9 is integrally formed with 
the support 8. The lever 9 near the free end is provided with anti-slip 
recesses 91. The plug 5 may be rotated relative to the housing 2 by 
gripping the lever with fingers to apply torque thereto. 
It is to be noted that all the channels 40a-40c in the branches 4a-4c are 
commonly in flow communication when the lever 9 is turned opposite to the 
branch 4b. 
The lever for rotating the plug is not limited to a unidirectional lever as 
illustrated. For example, two or more radial legs extending from the 
support or a wheel mounted on the support may be used. 
On the top surface of the lever support 8, there are provided arrow marks 
82a, 82b and 82c indicating the direction of respective barrel channels 
7a, 7b and 7c of the plug 5. Also, the lever 9 bears an appropriate 
indication 92 on the top. Since the lever is positioned relative to the 
barrel channels 7a-7c such that one of the branch channels 40a-40c which 
comes in register with the lever 9 is closed, the indication 92 should 
preferably have such a meaning. Characters "OFF" is used in the 
illustrated example. The marks 82 and indication 92 may be formed by any 
desired techniques including paint drawing, printing, stickers or 
inscription. 
In one embodiment, the marks 82 and indication 92 are uniquely formed as 
best shown in FIG. 3. The lever support 8 and lever 9 (more exactly their 
base member) is formed of a first material designated A in the figure and 
covered with a second material designated B in the figure over the entire 
outer surfaces except those areas corresponding to the marks 82 and 
indication 92. In some areas like an area near the center of the lever in 
FIG. 3, an inner recess in the first material is filled with the second 
material B. It suffices that the first and second materials A and B are 
different in color and brightness. Then the marks 82 and indication 92 are 
exposed distinct from the remaining cover surface. Materials A and B may 
be integrated by adhesive bonding or fusion welding, but integral forming 
by multi-color (two-color) molding or mold shaping is preferred for 
structural rigidity. 
The lid 10 is a disk member having a central stub 11 extending axially 
therefrom. The lid 10 is adapted to fit in the bottom of the cylindrical 
portion 3 of housing 2 to sealingly close the bore 31 at one end, that is, 
the bottom end in the illustrated embodiment. When the lid 10 is attached 
to the housing 2 to complete a cock, the lid stub 11 is received in a 
recess or opening 61 which is defined at the lower end of the barrel 6 as 
shown in FIG. 3. 
Although the three-way cock has been described as a typical example, the 
cock may be provided with four or more branches extending in four or more 
directions if desired. 
It is also contemplated herein to couple a plurality of three-way cocks 
having the above-mentioned construction through any suitably selected 
branches to form an ensemble of cocks as shown in FIG. 5. 
Next, the materials of which respective components of the three-way cock 
are made are described. 
The housing 2 is generally formed of rigid materials such as metals and 
rigid resins to provide necessary rigidity although rigid resins are 
preferred for several reasons including ease of molding. Such rigid resins 
include polycarbonates, polyamides, and the like. Preferably, the housing 
materials have a modulus in flexure of about 20,000 to about 30,000 
kgf/cm.sup.2. Use of transparent material is advantageous for a view 
through the housing 2. 
The plug 5, particularly its barrel 6, more particularly material A in FIG. 
3, is formed of a polyester elastomer. A variety of polyester elastomers 
may be used while polyether polyester elastomers are preferred. 
The preferred polyether polyester elastomers have a structure of the 
formula: 
##STR2## 
wherein n is a number of from 1 to 50, especially 2 to 30, 
m is a number of from 1 to 5, 
p is a number of from 1 to 8, 
q is a number of from 1 to 8, and 
x is a number of from 5 to 50, especially 10 to 30. 
The elastomers of the formula wherein n is 2 to 30, m is 1, p is 3, q is 4, 
and x is 10 to 30 are commercially available as Perprene.RTM. 
(manufactured and sold by Toyobo K. K.). 
The use of such elastomers as the plug 5 or barrel 6 is effective in 
preventing chipping or any failure of the barrel by scraping, abrasion, 
and other frictional actions caused when the plug 5 is inserted into the 
housing 2 and when the plug 5 is rotated therein during cock operation. In 
addition, the elastomers have high biological affinity and are free of 
dissolving-out toxic substances, and are least susceptible to thrombus 
adhesion when the cock is used for blood transfusion. 
The polyester elastomers as typified by Perprene have widely varying 
physical properties. Preferably, they have a modulus in flexure of at 
least 800 kgf/cm.sup.2, more preferably at least 1,000 kgf/cm.sup.2, 
further preferably at least 1,200 kgf/cm.sup.2, and most preferably at 
least 3,000 kgf/cm.sup.2. The upper limit is usually 15,000 kgf/cm.sup.2. 
A modulus in flexure of at least 800 kgf/cm.sup.2 ensures that any 
failures like chipping do not occur, irrespective of the identity of the 
housing 2 (including its material and hardness) and the diameter of the 
openings 70a-70c being enlarged to 2.0 to 3.0 mm or larger. Below this 
lower limit, the barrel can be deformed under pressure to allow leakage 
though no scraping occurs. 
For similar reasons, the polyester elastomers preferably have a surface 
hardness of about 95 to 100 as measured in Shore A hardness according to 
JIS K-6301. 
The second material B used as a surface cover of the plug 5 as shown in 
FIG. 3 is not particularly limited because they serve no substantial 
function. For firm bonding to the base material A, the cover material B 
should preferably be of the same type as material A, that is, contain a 
major proportion of a polyester elastomer. No limitations regarding 
modulus and hardness are imposed to cover material B. The cover material B 
preferably contains a pigment for coloring purpose because it should be 
distinguished in color, brightness or appearance from base material A. 
The lid 10 may be formed of any desired material and is typically of the 
same material as the housing 2. 
Now, the operation of the three-way cock 1 is described with reference to 
FIG. 4. On use, sections of tubing 12a, 12b and 12c are connected to the 
branches 4a, 4b and 4c of the housing 2, respectively. 
When the lever 9 of the plug 5 is turned to the position shown by solid 
lines in FIG. 4, that is, in register with the branch 4c, the branch 
channels 40a and 40b come in flow communication via the channels 7b and 7c 
in the plug barrel 6 with the branch channel 40c sealed by the outer 
surface 60 of the plug barrel 6. 
When the lever 9 of the plug 5 is turned to the position shown by phantom 
lines in FIG. 4, that is, in register with the branch 4b, the branch 
channels 40a and 40c come in flow communication via the channels 7a and 7c 
in the plug barrel 6 with the branch channel 40b sealed by the outer 
surface 60 of the plug barrel 6. 
In one example where the section of tubing 12a is connected to a living 
body (not shown) side and the sections of tubing 12b and 12c connected to 
supply sources of two different medicaments (not shown), either one of the 
two medicaments can be selectively supplied to the living body by turning 
the lever 9 to either of the solid and phantom line positions in FIG. 4. 
When the lever 9 of the plug 5 is turned to the position in register with 
the branch 4a (see FIG. 1), the branch channels 40b and 40c come in flow 
communication via the channels 7a and 7b in the plug barrel 6 with the 
branch channel 40a blocked by the outer surface 60 of the plug barrel 6. 
The operator can manipulate the lever 9 to rotate the plug 5 without an 
error because he or she can see the marks 82a-82c and "OFF" indication 92. 
In addition, as previously described in conjunction with FIG. 1, the 
three-way cock 1 is designed such that the rotating restrainer 81 on the 
plug 5 comes in engagement with the stationary restrainer 32 on the 
housing 2 on either of opposite ends to restrain further movement of the 
plug 5 when the lever 9 is positioned in register with the branch 4a or 
4c. Therefore, the operator can feel a physical engagement so that 
positioning operation is easy and accurate. Further, although the plug 5 
is rotated against the friction between the outer surface 60 of barrel 6 
and the inner surface of housing 2, such turning manipulation can be done 
by applying relatively small torques to the lever 9 because the barrel 6 
is formed of a polyester elastomer. 
EXAMPLE 
Examples of the invention are given below by way of illustration and not by 
way of limitation. 
Examples 1-12 and Comparative Examples 1-15 
Three-way cocks of the above-illustrated structure were prepared. The 
diameter of barrel channel openings and the type and modulus in flexure of 
plug material were changed. The barrels of Examples 1-4, 5-8 and 9-12 were 
prepared from polyester elastomers while the barrels of Comparative 
Examples 1-5, 6-10 and 11-15 were prepared from comparative materials. The 
opening diameter, material, and modulus in flexure are shown in Tables 1 
to 3. 
The three-way cocks had the following specifications. 
Housing: 
Cylinder inner diameter: 8.4 mm 
Branch channel diameter: 2.5 mm 
Material: polycarbonate modulus in flexure 2.3.times.10.sup.4 kgf/cm.sup.2 
Plug: 
Barrel outer diameter: 8.6 mm 
Barrel channel diameter: 2.5, 1.8 or 3.0 mm (=opening diameter) 
Barrel material: reported in Tables 1-3 
In each example, the cocks were examined for barrel channel edge scraping 
and air-tight seal as follows. 
Scraping 
First, the plug was inserted into the housing to complete a cock assembly. 
It was visually observed whether the barrel channels were scraped or 
chipped away at their opening edge. Next, the plug was rotated 200 
back-and-forth strokes over 180 degrees. Another visual observation was 
made whether the barrel channels were scraped or chipped away at their 
opening edge. 
Evaluation is based on the following criteria. 
O: no scraping 
.DELTA.: some scraping 
X: marked scraping 
Air-tight seal 
Three three-way cocks were connected as shown in FIG. 5. With the levers 
positioned as illustrated, the three cock arrangement was closed at one 
branch channel designated at X with a sealing member 13. Air under a 
pressure of 4 kgf/cm.sup.2 was introduced through another branch channel 
designated at Y. The cocks were examined for air leakage to evaluate the 
tight seal against pressurized air. While the cock arrangement was dipped 
in water, bubble emergence was checked. 
Evaluation is based on the following criteria. 
A: no bubble emerged 
B: some bubbles emerged 
C: many bubbles emerged 
Air-tight seal was examined both after assembly and after heavy duty plug 
rotation as in the scraping test. 
The results are shown in Tables 1 to 3. 
As seen from the experimental data, the cocks of the present invention are 
well durable in that their plugs undergo no failure like scraping, 
chipping and abrasion during insertion of the plug into the housing and 
during repetitive plug changeovers. 
Although some preferred embodiments have been described, many modifications 
and variations may be made thereto in the light of the above teachings. It 
is therefore to be understood that within the scope of the appended 
claims, the invention may be practiced otherwise than as specifically 
described. 
TABLE 1 
__________________________________________________________________________ 
Channel opening diameter 2.5 mm 
Plug material 
Modulus in 
Scraping after 
Air-tight seal after 
Example 
Type flexure (kgf/cm.sup.2) 
Assembled 
Rotated 
Assembled 
Rotated 
__________________________________________________________________________ 
E1 Perprene 13,000 .largecircle. 
.largecircle. 
A A 
E2 Perprene 5,000 .largecircle. 
.largecircle. 
A A 
E3 Perprene 3,000 .largecircle. 
.largecircle. 
A A 
E4 Perprene 1,000 .largecircle. 
.largecircle. 
A A 
CE1 Milastomer 
4,500 .DELTA. 
.DELTA. 
B B 
CE2 Milastomer 
3,200 .DELTA. 
.DELTA. 
B B 
CE3 High density PE 
12,500 .DELTA. 
.DELTA. 
B B 
CE4 Medium density PE 
6,500 X X B B 
CE5 Low density PE 
1,800 X X C C 
__________________________________________________________________________ 
TABLE 2 
__________________________________________________________________________ 
Channel opening diameter 1.8 mm 
Plug material 
Modulus in 
Scraping after 
Air-tight seal after 
Example 
Type flexure (kgf/cm.sup.2) 
Assembled 
Rotated 
Assembled 
Rotated 
__________________________________________________________________________ 
E5 Perprene 13,000 .largecircle. 
.largecircle. 
A A 
E6 Perprene 5,000 .largecircle. 
.largecircle. 
A A 
E7 Perprene 3,000 .largecircle. 
.largecircle. 
A A 
E8 Perprene 1,000 .largecircle. 
.largecircle. 
A A 
CE6 Milastomer 
4,500 .largecircle. 
.largecircle. 
A B 
CE7 Milastomer 
3,200 .largecircle. 
.largecircle. 
A B 
CE8 High density PE 
12,500 .largecircle. 
.largecircle. 
A B 
CE9 Medium density PE 
6,500 .largecircle. 
.DELTA. 
A B 
CE10 Low density PE 
1,800 .DELTA. 
X B C 
__________________________________________________________________________ 
TABLE 3 
__________________________________________________________________________ 
Channel opening diameter 3.0 mm 
Plug material 
Modulus in 
Scraping after 
Air-tight seal after 
Example 
Type flexure (kgf/cm.sup.2) 
Assembled 
Rotated 
Assembled 
Rotated 
__________________________________________________________________________ 
E9 Perprene 13,000 .largecircle. 
.largecircle. 
A A 
E10 Perprene 5,000 .largecircle. 
.largecircle. 
A A 
E11 Perprene 3,000 .largecircle. 
.largecircle. 
A A 
E12 Perprene 1,000 .largecircle. 
.largecircle. 
A A 
CE11 Milastomer 
4,500 .DELTA. 
.DELTA. 
B B 
CE12 Milastomer 
3,200 X X B B 
CE13 High density PE 
12,500 X X B B 
CE14 Medium density PE 
6,500 X X B B 
CE15 Low density PE 
1,800 X X C C 
__________________________________________________________________________ 
Perprene: trade mark of a polyether polyester elastomer by Toyobo K.K. 
surface hardness: Shore A 96 to 99 
Milastomer: trade mark of an olefinic elastomer by Mitsui PetroChemical 
K.K.