WO1992016295A1 - Packing ring for a pipette plunger - Google Patents

Packing ring for a pipette plunger Download PDF

Info

Publication number
WO1992016295A1
WO1992016295A1 PCT/FI1992/000075 FI9200075W WO9216295A1 WO 1992016295 A1 WO1992016295 A1 WO 1992016295A1 FI 9200075 W FI9200075 W FI 9200075W WO 9216295 A1 WO9216295 A1 WO 9216295A1
Authority
WO
WIPO (PCT)
Prior art keywords
packing ring
plunger
lip portion
cylinder
pipette
Prior art date
Application number
PCT/FI1992/000075
Other languages
French (fr)
Inventor
Osmo Suovaniemi
Original Assignee
Biohit Oy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Biohit Oy filed Critical Biohit Oy
Publication of WO1992016295A1 publication Critical patent/WO1992016295A1/en

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
    • B01L3/00—Containers or dishes for laboratory use, e.g. laboratory glassware; Droppers
    • B01L3/02—Burettes; Pipettes
    • B01L3/021—Pipettes, i.e. with only one conduit for withdrawing and redistributing liquids
    • B01L3/0217—Pipettes, i.e. with only one conduit for withdrawing and redistributing liquids of the plunger pump type

Definitions

  • the present invention concerns a packing ring for a pipette plunger, serving to seal the plunger against the inner surface of the cylinder.
  • the packing rings which are being used in existing high-precision pipettes fail to meet all those requirements mentioned in the foregoing which are imposed on the packing ring.
  • the object of the present invention is to eliminate the drawbacks to which reference has been made in the foregoing.
  • the invention is based on a packing design in which the packing forms a thin-walled lip portion pro ⁇ jecting in the direction of the piston, the inner diameter of said lip portion being fitted to press with sealing action against the outer surface of the piston moving relative to the packing ring.
  • the lip portion is advantageously thin-walled, its wall thickness on the order of 0.5 to 0.1 mm, e.g. 0.15 to 0.3 mm, advantage- ously about 0.2 to 0.25 mm.
  • the packing ring is made of resilient and de- formable plastic, such as polyolefines, fluorinated polyolefines, polyamides or other equivalent polymers generally known as packing materials.
  • the inner diameter of the packing ring advan ⁇ tageously constitutes a minimum at the lip portion, for enhancing the sealing action and for reducing friction.
  • the body portion of the packing ring may fur ⁇ ther constitute a groove encircling the lip portion, a tightening ring being placeable in said groove such as a conventional 0 ring, a spring, or equivalent, to press the lip portion against the plunger.
  • a locking groove for interlocking the packing ring with the inner cylinder surface, with the aid of a locking ring.
  • the packing ring is, in a certain embodiment, advantageously elongated, substantially shaped like a hollow cylinder, its length advantageously greater than its outer diameter, and it constitutes a guide for the plunger.
  • the packing ring made of highly elastic, shock-absorbing material, can be advan ⁇ tageously employed to attenuate vibration.
  • FIG. 1 presents a packing ring according to the inven ⁇ tion, sectioned
  • Fig. 2 shows the packing ring of Fig. 1, mounted in the cylinder volume of a motor-operated precision pipette
  • Fig. 3 presents another packing ring according to the invention, sectioned.
  • Fig. 1 is depicted a packing ring 1 accord ⁇ ing to the invention, in elevational view and partly sectioned; the same packing ring is shown in Fig. 2, mounted in position to seal the plunger 3 of a pipette 2 against the cylinder 4; in Fig. 2 the operating means of the pipette has not been shown, in order to illus ⁇ trate the design and function of the packing ring.
  • the packing ring comprises a body part 5 made of elastic material, this body part being disposed to effect sealing against the inner surface 6 of the cylinder 4 of the pipette 2. Furthermore, the body part 5 provides a thin-walled lip portion 7 pro ⁇ jecting in the direction of the plunger 3 towards the tip 10 of the pipette. The inner surface 8 of said lip portion is disposed to press and seal against the outer surface 9 of the plunger 3 moving relative to the pack ⁇ ing ring.
  • the packing ring constitutes a ring sealed against and interlocked with the inner surface of the cylinder, its lip portion, presenting the mini ⁇ mum of the packing ring's inner diameter, being ar ⁇ ranged to press and seal slidably against the outer surface of the plunger.
  • the body part forms a groove 11 encircling the lip portion 7, in which a particular tightening ring 12 has been placed, such as an 0 ring or a spring, to press the lip portion with sealing effect against the plunger 3.
  • a particular tightening ring 12 such as an 0 ring or a spring
  • the sealing of the plunger and the friction of the plunger against the cylinder can be adjusted to be such as is desired, by exchanging the tightening ring, in other words, the tightening ring can be sel ⁇ ected in connection with manufacturing the device, to meet any desired operating conditions and characterist ⁇ ics.
  • a par ⁇ ticular locking groove 13 has been provided on the outer surface of the body part 5 of the packing ring 1 , a locking ring 14 being placed in said groove to inter ⁇ lock the packing ring with the inner surface of the cylinder 4.
  • This locking ring may consist e.g. of an 0 ring, a D ring, or another equivalent locking ring known in the art.
  • Fig. 3 is shown an embodiment in which the packing ring 1 is elongated, substantially cylinder- shaped and constitutes a guide for the plunger. The length 1 of the packing ring is greater than the diameter d of the ring.
  • the packing ring is made of elastic, shock-absorbing material, and it absorbs vibrations and movements of the plunger.
  • the packing ring shown in Fig. 3 constitutes an efficient positive plunger guide.
  • the packing ring shown in Fig. 3 is equivalent to the embodiment of Figs 1-2 as regards the lip portion 1 , the tightening ring groove 12 and the groove 13 for the locking ring 14.
  • the inner surface 6 of the cylinder 4 forms an expanded portion 15 with abutment border 16.
  • the packing ring 1 is placed in said expanded portion 15 in such manner that the thicker part of the packing ring projecting over the groove encircling the lip por- tion 7, i.e., the sealing portion 17 (Fig. 1) pushes against said abutment border 16.
  • the pipette is fur ⁇ thermore provided with a tightening member, such as a spring 18, arranged to press the packing ring against the abutment border 16.

Abstract

A packing ring (1) for sealing the plunger (3) of a pipette (2), comprising a body part (5) which forms a thin-walled lip portion (7) projecting in the direction of the plunger and its inner surface (8) disposed to press and to seal against the outer surface (9) of the plunger (3) moving relative to the packing ring (1).

Description

PACKING RING FOR A PIPETTE PLUNGER.
The present invention concerns a packing ring for a pipette plunger, serving to seal the plunger against the inner surface of the cylinder.
In high-precision pipettes employed in medical analytics, certain problems are inherent in the sealing of the plunger against the inside of the cylinder. Primary importance attaches to absolutely tight sealing under all and any conditions independent of the pipet¬ te's degree of filling, filling status (filling/emp¬ tying) and potential manufacturing errors of the cylin¬ der, such as uneven surfaces for instance. It is furt¬ her required that the friction between plunger and cylinder be made such as is desired, so that no prob¬ lems may arise from friction in filling or emptying the pipette nor, particularly, regarding measuring accur¬ acy, in spite of the operating means. Moreover, there may occur, in some motor-operated pipettes, vibration of the plunger relative to the cylinder, resulting from vibration caused by the motor or other operating means. Owing to the causes mentioned, extremely high requirements are imposed on a pipette plunger packing, regarding structural design and function of the packing ring.
The packing rings which are being used in existing high-precision pipettes fail to meet all those requirements mentioned in the foregoing which are imposed on the packing ring. The object of the present invention is to eliminate the drawbacks to which reference has been made in the foregoing.
It is a particular aim of the invention, to provide a novel packing ring for sealing a pipette plunger in the cylinder in such a way that the sealing is efficient under all and any conditions, and in all and any states of application of the pipette. It is further an object of the invention, to provide a packing ring which produces between the plunger and cylinder of the pipette an accurately pre- determinable friction. It is further an object of the invention, to provide a packing ring which can be used to eliminate plunger vibration e.g. in motor-driven precision pipet¬ tes, and particularly to centre the plunger accurately and with forced guidance in the cylinder. Regarding the features characterizing the invention, reference is made to Claim 1.
The invention is based on a packing design in which the packing forms a thin-walled lip portion pro¬ jecting in the direction of the piston, the inner diameter of said lip portion being fitted to press with sealing action against the outer surface of the piston moving relative to the packing ring. The lip portion is advantageously thin-walled, its wall thickness on the order of 0.5 to 0.1 mm, e.g. 0.15 to 0.3 mm, advantage- ously about 0.2 to 0.25 mm.
The packing ring is made of resilient and de- formable plastic, such as polyolefines, fluorinated polyolefines, polyamides or other equivalent polymers generally known as packing materials. The inner diameter of the packing ring advan¬ tageously constitutes a minimum at the lip portion, for enhancing the sealing action and for reducing friction. The body portion of the packing ring may fur¬ ther constitute a groove encircling the lip portion, a tightening ring being placeable in said groove such as a conventional 0 ring, a spring, or equivalent, to press the lip portion against the plunger.
Furthermore, on the outside surface of the packing ring is advantageously provided a locking groove for interlocking the packing ring with the inner cylinder surface, with the aid of a locking ring.
The packing ring is, in a certain embodiment, advantageously elongated, substantially shaped like a hollow cylinder, its length advantageously greater than its outer diameter, and it constitutes a guide for the plunger. In this embodiment the packing ring, made of highly elastic, shock-absorbing material, can be advan¬ tageously employed to attenuate vibration.
The invention is described in the following in detail with the aid of embodiment examples, referring to the attached drawing, wherein:- Fig. 1 presents a packing ring according to the inven¬ tion, sectioned,
Fig. 2 shows the packing ring of Fig. 1, mounted in the cylinder volume of a motor-operated precision pipette, and Fig. 3 presents another packing ring according to the invention, sectioned.
In Fig. 1 is depicted a packing ring 1 accord¬ ing to the invention, in elevational view and partly sectioned; the same packing ring is shown in Fig. 2, mounted in position to seal the plunger 3 of a pipette 2 against the cylinder 4; in Fig. 2 the operating means of the pipette has not been shown, in order to illus¬ trate the design and function of the packing ring.
In Figs 1-2, the packing ring comprises a body part 5 made of elastic material, this body part being disposed to effect sealing against the inner surface 6 of the cylinder 4 of the pipette 2. Furthermore, the body part 5 provides a thin-walled lip portion 7 pro¬ jecting in the direction of the plunger 3 towards the tip 10 of the pipette. The inner surface 8 of said lip portion is disposed to press and seal against the outer surface 9 of the plunger 3 moving relative to the pack¬ ing ring. Hereby the packing ring constitutes a ring sealed against and interlocked with the inner surface of the cylinder, its lip portion, presenting the mini¬ mum of the packing ring's inner diameter, being ar¬ ranged to press and seal slidably against the outer surface of the plunger.
In Figs 1-2, the body part forms a groove 11 encircling the lip portion 7, in which a particular tightening ring 12 has been placed, such as an 0 ring or a spring, to press the lip portion with sealing effect against the plunger 3. Thanks to said tightening ring, efficient sealing is present in all and any cir¬ cumstances and independent, e.g., of minor manufactur¬ ing errors that may be found on the plunger surface. Moreover, the sealing of the plunger and the friction of the plunger against the cylinder can be adjusted to be such as is desired, by exchanging the tightening ring, in other words, the tightening ring can be sel¬ ected in connection with manufacturing the device, to meet any desired operating conditions and characterist¬ ics.
In the embodiment depicted in Figs 1-2 a par¬ ticular locking groove 13 has been provided on the outer surface of the body part 5 of the packing ring 1 , a locking ring 14 being placed in said groove to inter¬ lock the packing ring with the inner surface of the cylinder 4. This locking ring may consist e.g. of an 0 ring, a D ring, or another equivalent locking ring known in the art. In Fig. 3 is shown an embodiment in which the packing ring 1 is elongated, substantially cylinder- shaped and constitutes a guide for the plunger. The length 1 of the packing ring is greater than the diameter d of the ring. The packing ring is made of elastic, shock-absorbing material, and it absorbs vibrations and movements of the plunger. The packing ring shown in Fig. 3 constitutes an efficient positive plunger guide. The packing ring shown in Fig. 3 is equivalent to the embodiment of Figs 1-2 as regards the lip portion 1 , the tightening ring groove 12 and the groove 13 for the locking ring 14.
In Fig. 2, the inner surface 6 of the cylinder 4 forms an expanded portion 15 with abutment border 16. The packing ring 1 is placed in said expanded portion 15 in such manner that the thicker part of the packing ring projecting over the groove encircling the lip por- tion 7, i.e., the sealing portion 17 (Fig. 1) pushes against said abutment border 16. The pipette is fur¬ thermore provided with a tightening member, such as a spring 18, arranged to press the packing ring against the abutment border 16. The embodiment examples are only meant to illustrate the invention, and the embodiments of the invention may vary within the scope of the claims fol¬ lowing below.

Claims

1. A packing ring (1) for sealing the plunger (3) of a pipette (2) in the cylinder (4), comprising a body part (5) made of elastic material and disposed to seal against the inner surface (6) of the cylinder, characterized in that the body part (5) forms a thin- walled lip portion (7) projecting in the direction of the plunger (3) and its inner surface (8) disposed to press and to seal against the outer surface (9) of the plunger (3) moving relative to the packing ring (1).
2. Packing ring according to claim 1, char¬ acterized in that the lip portion (7) projects towards the tip (19) of the pipette (2).
3. Packing ring according to claim 1 or 2, characterized in that the body part (5) forms a groove
(11) encircling the lip portion (7) and in which is placed a tightening ring (12) to press the lip portion against the plunger (3) .
4. Packing ring according to any one of claims 1-3, characterized in that on the outside sur¬ face of the body part (5) is provided a locking groove (13) for interlocking the packing ring with the aid of a locking ring (14) with the inner surface (6) of the cylinder (4) .
5. Packing ring according to any one of claims 1-4, characterized in that the packing ring (1) is elongated, substantially shaped like a hollow cylin¬ der, and constitutes a guide for the plunger.
6. Packing ring according to any one of claims 1-5, characterized in that the inner diameter of the packing ring (1) has a minimum at the location of the lip portion.
7. Packing ring according to any one of claims 1-6, characterized in that the packing ring (1) is made of elastic polymer, such as polyolefines, fluorinated polyolefines, polyamides or other equival¬ ent polymers.
PCT/FI1992/000075 1991-03-19 1992-03-18 Packing ring for a pipette plunger WO1992016295A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FI911346A FI86970C (en) 1991-03-19 1991-03-19 LUTE
FI911346 1991-03-19

Publications (1)

Publication Number Publication Date
WO1992016295A1 true WO1992016295A1 (en) 1992-10-01

Family

ID=8532148

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FI1992/000075 WO1992016295A1 (en) 1991-03-19 1992-03-18 Packing ring for a pipette plunger

Country Status (2)

Country Link
FI (1) FI86970C (en)
WO (1) WO1992016295A1 (en)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008076817A1 (en) * 2006-12-18 2008-06-26 Parker-Hannifin Corporation Pipette seal
EP2108450A1 (en) * 2008-04-11 2009-10-14 Socorex Isba S.A. Sealing for liquid dispensing device
WO2009125337A1 (en) * 2008-04-08 2009-10-15 Socorex Isba S.A. Joint for device for metering liquids
WO2012085006A1 (en) * 2010-12-21 2012-06-28 Ge Healthcare Uk Limited Filtration device and method
DE102015213005A1 (en) * 2015-07-10 2017-01-12 Hamilton Bonaduz Ag Pipetting device with an expansible coupling formation for coupling a pipetting tip and a pipetting tip formed therefor
CN107387391A (en) * 2017-07-25 2017-11-24 盐城美希密封件有限公司 A kind of static seal device of auto pump

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3847389A (en) * 1968-12-16 1974-11-12 Tanner Eng Co Low-friction seal
DE2736586B2 (en) * 1976-08-25 1979-06-07 Oxford Laboratories Inc., Foster City, Calif. (V.St.A.) LIQUID DISPENSER
CH642570A5 (en) * 1978-09-08 1984-04-30 Metsaele Seppo Juhani PIPETTE.
US4618153A (en) * 1983-12-01 1986-10-21 Volvo Bm Ab Annular reinforced wiper for piston rods

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3847389A (en) * 1968-12-16 1974-11-12 Tanner Eng Co Low-friction seal
DE2736586B2 (en) * 1976-08-25 1979-06-07 Oxford Laboratories Inc., Foster City, Calif. (V.St.A.) LIQUID DISPENSER
CH642570A5 (en) * 1978-09-08 1984-04-30 Metsaele Seppo Juhani PIPETTE.
US4618153A (en) * 1983-12-01 1986-10-21 Volvo Bm Ab Annular reinforced wiper for piston rods

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008076817A1 (en) * 2006-12-18 2008-06-26 Parker-Hannifin Corporation Pipette seal
WO2009125337A1 (en) * 2008-04-08 2009-10-15 Socorex Isba S.A. Joint for device for metering liquids
US8900526B2 (en) 2008-04-08 2014-12-02 Socorex Isba S.A. Joint for device for metering liquids
US20150086448A1 (en) * 2008-04-08 2015-03-26 Socorex Isba S.A. Joint for Device for Metering Liquids
EP2108450A1 (en) * 2008-04-11 2009-10-14 Socorex Isba S.A. Sealing for liquid dispensing device
WO2012085006A1 (en) * 2010-12-21 2012-06-28 Ge Healthcare Uk Limited Filtration device and method
CN103370134A (en) * 2010-12-21 2013-10-23 通用电气医疗集团英国有限公司 Filtration device and method
US9919248B2 (en) 2010-12-21 2018-03-20 Ge Healthcare Uk Limited Filtration device and method
DE102015213005A1 (en) * 2015-07-10 2017-01-12 Hamilton Bonaduz Ag Pipetting device with an expansible coupling formation for coupling a pipetting tip and a pipetting tip formed therefor
CN107387391A (en) * 2017-07-25 2017-11-24 盐城美希密封件有限公司 A kind of static seal device of auto pump

Also Published As

Publication number Publication date
FI86970B (en) 1992-07-31
FI86970C (en) 1992-11-10
FI911346A0 (en) 1991-03-19
FI911346A (en) 1992-07-31

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