Note: Descriptions are shown in the official language in which they were submitted.
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The embodied methods, devlce and system relate to
precision moveTnent o small vol~nes of fluid,
Generally speaking, the movement of small volumes of
fluid, for example liquid chemicals and reagents in analysis
arrangements, has been accomplished by several forms of devices
and systems having as a common goal the precise reproducibility
of the vol~ne movement, i.e, displacement. The embodiments
: hereinafter disclosed also have the goal of volume displacem~nt
reproducibility with the use of a displacement device having a
. cavity in which there is a diaphragm which is pressure driven
; between two opposite stable conditions, which enables the
vol~me o ~he cavity to deine the desired volume displacement,
: l'he pri~ari1y e~bodiPd di~phra~m does not have to be of an
e1~s~omeric ma~erial and can be inert ~o a large ran~e of
! 15 chemicals.
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In a fluid displacem2nt systeT.n~ it is desirable that a
~ minimum of cross-contamination between samples be incurred.
Accordingly, a method and system of sampling a liquid utilizin~
the fluid displacement device hereinaf~er to be described in
~ 20 detail, provides for a minimum of cross-contamination between
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liquid samples.
:.
.J ~ccording to t'ne invention there i9 provided a method o
making a fluid displacem~nt device which has asubs~antially
-
' constant voluTne displacemen~, said met:~od comprisin~ the
,.
.~. 25 steps of: employing a hollow ~ody of filced volume with
. ` oppositely facing, interlor, sim:ilarly sllaped concave suraces
; ~ 2 ~
~ 6
having substantially eq-~al surface areas, deforming permanently
a flexible diaphragm to ca~se it to have subs~antially the same
shape and surface area as the shape and surface area of each
concave surface; clamping the periphery of the diaphragm
between the peripheries of the concave surfaces 9 and thereby
mounting the diaphragm for movement between and against the
- concave surfaces; diaphragm movement from one surface to th~
other surace defining the fixed volume to be displaced.
According to the invention there further is provided
a fluid displacement d~vice made in accordance with the just
above set forth method.
According ~o the invention there rurther is pro~ided a
method ~or utilizir.g a fluid displa~ement device of the t~p2
described, t~e device being couplQd to a sampllng ele~en~ for
` 15 sampling a precise amount of a sample material from a source
thereof, comprising ~he s~eps orO placin~ the diaphragm in a
predetermined first position intermediate the two concave
surfaces of the hollow body of the device, the diaphra~m and a
~irst of the concave surfaces defining therebetween a prede-
~ermined first volume which is significan~ly less than the total
displacement volume of the device; the samplin~ element being
in fluid connection with the interior of the displacement device
~!, by way of its ~second concave surface, and the sampling cl2m2n~
being in contact with the sample material; moving the diaph~a~m
to a second position conforming against the first conca~e
surface and thereby drawing into the sampling element a first
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~ . . . .
~ S~ 6
vol~me of the sample material equal to said first defined
volume; separating the sampling ele~ent from the source of
sample and moving the diaphragm to a thlrd position confo~ming
against the second of the concave surfaces and thereby dispens-
ing ~rom ~he sampling element a total volume equal to the total
: displacement volume of the device a~d ~h~s all of said first
volume of the sample material and an additional volume of
substance, such as air, for cleaning sampling element prior to
a next cycle of sampling by this method.
~ .
The preferred embodiments of this lnvention now will be
described, by way of example, with reference to the dra~7ings
acco~panying this specification in which:
~îgu~e 1 i5 a ront perspecri~e vie~q oE ~ fluid displace~
`; ment device;
Figure 2 is an exploded perspective view oE the de~Jice
sho~n in Figure l;
Figure 3 is a sectional view taken ~hrough the device
along the line 3-3 of Figure 1 and in the general direction
indicated;
Figure ~ is a vertical plan vie~J par~ially schema,ic and
with por~ions broken away of one embodiment of a liquid
sampling system embodying the device o~ Figure l; and
~~ Figures 5A-5~ ar2 vertical planviews partially schem2tic
and wi~h portions broken a~ay o ~nother embodiment of ~he
'j 25 liquid sampling system of Flgure 4 showing different stages of
operation thcreof.
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Referring to Figure 1, the embodied fluid displacement
device 10 has three principal partsO T~o of the parts are a
pair of mating half shells 12, 14 which can be injection-molded
an~ preferably are substantially identical and possess annular
flanges 19, The third part is a flexible diaphragm 16 sand-
wiched between the two shell halves 12 and 14 and held in
place by fasteners engaged through registering openings in the
annular flanges,
Each shell has a nipple 22, 24 ~hich is connectable to
conduits 26, 28 for connecting the fluid displacement device
into a fluid system, such as sho~ in Figure 4.
Referring to Figure 2, the shells 12, 14 have chambers 30
- and 32 each bordered by its flange 19. Each of the flanges 19
includes an annular clamping ring 41, 42 having the diaphragm
16 sandwiched therebetween.
Diaphragm 16 is clamped between the shells in such a
. manner that the total area of the diaphra~m within the clzmping
- rings 41, ~2 is greater than the central planar area derined
by the annular ring by an amo~mt su~ficient for the diaphragm
to be able to conform with and alternately lie against the
interior sur~ace of the chambers 30, 32. During construction
~; the diaphragm is assembled and pressure is applied to drive
~:~ the diaphragm into engagement and conform with the inner surface
of one chamber of one shell, While in this condi~ion, the
shells are permanently fastened together, Thereafter, the
diaphragm can be moved by fluid pressure dlffer~ntials from one
~06~59~i
to the other interior surf~ce of the device in a toggle-like
action, with little or no stre~clhing of the diaphragm.
The term "toggle-lilce action" is employed herein to
designate the property of the diaphragm and the operation of
the device 10, which provides two stable s~ate positions, as
shown in Figure 3 as 16 and 16', both conforming wi~h the
inner wall of the chambers 30 and 32~ Suitable differential
pressure is employed to drive, by pushing or pullingj~the
diaphrag~i through its "toggle-like action".
Hence, the diaphragm can be of a material which is not
elastomeric~ For example, the dia?hra~m can be made of
polytetrafluoroethylene which also is quite inert.
Each of the shells has an antechamber 46, 48 interposed
bet~een the nipples 22, 24 and the chambers 30, 32. Tne ante-
chambers 46 and 48 enable suficient differential pressure to
be applied to either side of the diaphragm 16 to cause the
diaphragm to toggle back and forth.
When the diaphragm is being moved into position 16 ',
-
; fluid will be forced out of the chamber 32 ~ia the entry ori~
ice 46 through the nipple 24, and fluid ~ill be forced into
the chamber 30 via the entry orifice 48 through the port 42
~, from tube 26 coupled thereto.
The fluid volume displaced by the toggLe-like action o
the diaphragm 16 will not change ~7ith time, since the ~olume
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~ .3~ 25 - is dependant only upon the fixed vol~me of the chambers 30 and
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32; hence, an accurately ~eproducible volume displacement of
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~luid is achieved by the subject ~evice 10.
A llquid sampling system utilizing the fluid displacement
device 10 of ~igures 1 - 3 generally is indicated by the
reference numera1 110 in ~igure 4. The system 110 includes a
sampling element, ~or example a cuvette 112, the fluid dis-
placement device 10, a fluid connection line 116 connecting the
device 10 with the upper end 117 of the cuvette 112, and a line
152 between the device 10 and a control valve arrangement 118
for controlling the operatlon o~ the device 10. The arrangement
of the ~ntechambers 46, 48 and niy~les 2~, 24 are not sllown in
Figure 4, for simplicity of drawing. The valve arrangement
118 includes a control valve 154 and a throttling device 156
~` in ~he ~orm o a needle valve. A~ sllo~m, a fluid line 15~
le~ding to a source o vacuum and a fluid line 160 leadin~ to
a source of pressure are connected to the valve 154,
. .
In the illustrated embodiment o~ the liquid sampling system
110 sho~.*n in Figure 4, an air line 162 with a valve 16~ therein
- is connected into the ~luid line 116 between the displacement
device 10 and the cuvette 112. The valve 164 is operable to
.' 20 communic~te pressurized air throu~h the flui~ line 116 to the
upper end 117 o~ the cuvette 112,
,
/ T11e method of usinS tlle syste;n 110 is initiated by oper-
:;1 ating the valve 154 to connect the pressure line 160 through
the throttling device 156 to the volume displacement dev~ce 10
to push ~he diaphragm 16 upward against the inner surLace o
the cavity 30, Then, the lower end 122 of the cuvette 112 is
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1~6~591~
placed lnto a body of sample liquid 166 3 as ~n a test tube 168.
Next, the valve 154 is operated to connect the vacuum line 158
to the device 10 to pull the diaphragm downwardly to the
position shown in Figure 4. In this way, a precise quan~ity of
fluid is drawn up frcm the body of liquid 166 in~o the cuvette
112. The needle valve 156 throttles the suction applied to
the device 10 so that the diaphragm 16 can move slowly from
the sur~ace of the cavity 30 to the sur~ace o the cavity 32,
As a result, the liquid drawn into the cw ette 112 is drawn
thereinto slowl~J and smoothly without splashing of the liquid
~; into the upper end 117 of the cuvette 112.
Al~hough the sampling el~ment 112 is no~. a limitation upon
the scope o the invention, the cuvette 112 and pho~ometric
elemen~s 13~ and 132 are described as a prac.tical exam~le. A
photometric analysis now can be made by passing li~ht throug~
the cuvette from the source L30 to the photosensi~ive device
132. Before or after the photometric analysis, the lower end
122 of the cuvette 112 is removed from the bod~J of liquid 166.
Then, after the photometric analysis has been made, the valve
154 is operated again to connect the pressure line 1~0 to the
volume displacement device 10~ to move the diaphra~m 16 against
:, ,.
i the inner surface of the cavity 30 and thereby force the liquid
out of the cuvette 112. Next, with the lowe~ end of the
~ j
.~ cuve,tte 122 open to the ambient air above a waste container
:~ 25 (not showm), the valve 154 is opera~ed to connect the vacuu~
I line 158 to device 10 to draw a quantity of air into the
:! 8
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i
lOG15~3~
cuvette 112 after which the val~e 154 is connected to the
pressure line 160 to operate the devîce lO to force the air
out of the cuvette 112 and in so doing to eject from the
cuvette any droplets of liquid ~'nich may have clung to the
interior side walls o~ the cuvette.
As a modification to the method of operating the liquid
sampling system described above, after the liquid sample is
ejected from the cuvette 112, the cuvette 112 can be lowered
into a source of rinse liquid which is then dra~ up into the
cuvette and subsequently purged from the cuvette prior to the
drawing o~ air into the cuvette. This is accomplished by
operating the valve 154 in the manner described above to oper-
- a~e tlhe volume displacement device 10 in the ma~ner ~.escr~bed
abcve~
Also, and to save time and to provide for a better blowing
out of liquid from the cuvette 112, the step of pushin~ air
through the cu~ette 112 can be performed or assisted by operat
ing the valve 164 to transmit pressurized air in the line 162
- through the fluid line 116 to the interior of the cuvette 112.
- 20 With this modification, the device 10 need not be operated to
pull air into and then force air out of the cuvette 112,
Turning no~ to Figures 5A - 5D, another method o~ operating
the ~mbodied liquid sampling is shown. With appropriate
..
I pressure differential being applied to the dlaphragm 16, it
; 25 will lie in a neutral position between the shells 12, 14 as
shown in Figure 5A.
_ g _
106~5~6
The valve arrangement 218 is operable to connect the
cavity 30 to either a line 244 leading to ambient air, a llne
246 leading to a source of vacuum or to a llne 248 leadin~, to
a source of pressure. If desired~ a connecting line 250 of the
valve arrangement 218 can include a throttling device similar
to the needle valve 156 shown in Figure 4.
In the method of util~zing the liquid sampling system and
assuming the neutral diaphra~m position divides the volume
defined by the cavities 30 and 32 in half, the valve arrangement
218 is operated to connect the cavity 30 to the ambient air
- line 244 so that the diaphragm 16 is in a neutral position with: half of the volume capacity of the device 10 on either side of
the diaphragm and with air in the cavity 32~ It is lmclerstood
that the diaphragm 16 can have a neutral position which i9 not
necessarily at the midpoint of the chamber defined by the ~:
.` cavities 30 and 32. Then the lower en~ 122 of the cuvette is
lowered into the body of liquid 166. SU'DSeqUent1Y, the valve
! arrangement 218 is operated to connect the cavity 30 to the
vacuum line 246 as sho~ in Figure 5B. This results in a
volume displacement o one-half the volume capacity of the .
', device 10 to draw that quantity o the liquid in the container
168 upwardly in~o the cuvet~e 11 After a photometric
analysis of the sample in the cuvette 112 is made and after
~;3 the cuvette is removed from the container 168 and placed Gver
-, 25 a waste fluid receptacle 260 shown in ~igure 5C, the valve
1' arrang2ement 218 is operated to comm.unicate the cavity 30 with
:;
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2:
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.'.' ."'. '.'.''' " '' ` .' ," ' ~" ,'"' ' . '," "'. .,', ' ' ."" '.~ ,'' .',,' ' , ''" '. " ' '' " " ' ' .
'1~6 ~ 5~ ~
the pressure line 248, The diaphragm 16 thus is moved
completely across the devlce 10 Erom tlle lnner surface of the
cavity 30 to the inner surface oE the cavity 32. In this way,
not only is the fluid in the cuvette 112 forced out of the
cuvette 112, but also a quantity of air,which had been stored
in the cavity 30 and which is equal to one-half the volume
displacement of the device lO,is orced out of the cuvette.
This quantity of air serves to remove droplets of the sample
liquid which may have clung to the interior side walls of the
cuvette 112. Subsequently, and as shown in Figure 5D, the
valve arrangement 218 is operated to connect again the ambient
air line 244 to the c~vity 30 so that the diaphra~m 16 is
- returned to its neutral position and a quantity of air equal
to one-half th~ volume displace~ent of the device 10 is dra~n
lnto the cavi~y 32. The system now is ready for the sampling
of ancither liquid sample from a next container.
. From the oregoing description, i~ will be apparent ~hat
the embodied displacement device, liquid samplin2 system and
~- the methods of liquid sampling described provide ror a very
-: ' `
ef~icient and precise sampling of liquid with li~tle or no
cross-contamination between samplings of liquid~
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