GB2121125A - Sealing arrangements - Google Patents

Sealing arrangements Download PDF

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Publication number
GB2121125A
GB2121125A GB08312706A GB8312706A GB2121125A GB 2121125 A GB2121125 A GB 2121125A GB 08312706 A GB08312706 A GB 08312706A GB 8312706 A GB8312706 A GB 8312706A GB 2121125 A GB2121125 A GB 2121125A
Authority
GB
United Kingdom
Prior art keywords
seal arrangement
arrangement according
tension member
sleeve
interposed
Prior art date
Legal status (The legal status 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 status listed.)
Granted
Application number
GB08312706A
Other versions
GB8312706D0 (en
GB2121125B (en
Inventor
Peter Richard Smith
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Smiths Group PLC
Original Assignee
Smiths Group PLC
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 Smiths Group PLC filed Critical Smiths Group PLC
Priority to GB08312706A priority Critical patent/GB2121125B/en
Publication of GB8312706D0 publication Critical patent/GB8312706D0/en
Publication of GB2121125A publication Critical patent/GB2121125A/en
Application granted granted Critical
Publication of GB2121125B publication Critical patent/GB2121125B/en
Expired legal-status Critical Current

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Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01FMEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
    • G01F23/00Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
    • G01F23/22Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
    • G01F23/24Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid
    • G01F23/241Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of resistance of resistors due to contact with conductor fluid for discrete levels
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16JPISTONS; CYLINDERS; SEALINGS
    • F16J15/00Sealings
    • F16J15/02Sealings between relatively-stationary surfaces
    • F16J15/06Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces
    • F16J15/10Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with non-metallic packing
    • F16J15/104Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with non-metallic packing characterised by structure
    • F16J15/106Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with non-metallic packing characterised by structure homogeneous

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Thermal Sciences (AREA)
  • Fluid Mechanics (AREA)
  • General Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Measuring Fluid Pressure (AREA)

Abstract

<IMAGE> <H0> Sealing arrangementst

Description

SPECIFICATION Seal arrangements This invention relates to seal arrangements.
The invention is more particularly, but not exclusively, concerned with arrangements for forming a fluid-tight seal in probes for use in boilers and other pressure vessels.
in hostile environments where high temperatures and pressures, and corrosive substances are met, the provision of fluid-tight seals is often difficult and expensive to achieve.
One example of such an environment is in steam boilers where various probes (such as for sensing pressure, temperature or water height, and so on) are required to extend through the outer wall of the boiler into its interior. These probes commonly have an electrical conductor which extends through, and is insulated from, an outer body that is screwed into an opening in the boiler wall. Various arrangements have been used for achieving a seal between the conductor and its insulator, such as by using glass seals or brazed joints. These, however, are expensive to make and necessitate a careful selection of materials which have similar thermal expansion properties -- this, however, can preclude the use of materials which are more suitable for the particular environment.
It is an object of the present invention to provide a seal arrangement that can be used to alleviate the above-mentioned disadvantage.
According to the present invention there is provided a seal arrangement comprising a first body, a second body arranged axially with said first body and having an axial bore therethrough, sealing means interposed between said first and second bodies, a tension member connected with said first body and extending through said second body, and resilient means interposed between said second body and said tension member such as to apply compression to said sealing means between said first and second bodies.
The resilient means may include a disc spring which may be of substantially frusto-conical shape. The tension member may include a rod having a screw-threaded portion, and a nut threaded on said portion, the resilient means embracing the rod and being interposed between the nut and the second body. The sealing means may comprise a sleeve that extends around the tension member, a first sealing ring interposed between one end of the sleeve and the first body, and a second sealing ring interposed between the other end of the sleeve and the second body. The or each end of the sleeve may be tapered and conform with a tapered recess in the first or second body. The first and second bodies and the tension member may be of electrically-conductive material, the sealing means may include an electrically-insulative member, and the tension member may be electrically insulated from the second body.An electrically-insulative member may be located intermediate the second body and the tension member.
A water-level sensing probe, including a seal arrangement, both in accordance with the present invention, will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a sectional side-elevation of the probe; and Figure 2 is a perspective view of a part of the probe.
The probe has a rear metal body 1 that is screwed into the wall 2 of a boiler and that supports an electrode tip 3 within the boiler. The tip 3 is connected to a metal terminal post 4 that is insulated from the rear body 1 and that extends rearwardly out of the boiler. By measuring the resistance between the terminal post 4 and the boiler wall, or another probe, it can be determined whether or not the tip 3 is immersed in water.
The tip 3 is of stainless steel, having an outer surface of frusto-conical shape at its forward end, and of cylindrical shape at its rear end. The rear end of the tip 3 is provided with a centrallypositioned bore 30 having three sections along its length. The forward section 31 is tapped, the intermediate portion 32 is tapered outwardly to form a frusto-conical surface, and the rear portion 33 is of cylindrical shape and increased diameter.
Into the tapped portion 31 of the bore is screwed the forward, threaded end 40 of the terminal post 4 which extends rearwardly, axially through the probe. In the intermediate portion 32 of the bore 30 there is located a sealing washer 51 of copper and of frusto-conical shape. The washer 51 is sandwiched tightly between the electrode tip 3 and the forward end surface 60 of an electrically-insulative alumina sleeve 61. The sleeve 61 is of generally cylindrical shape, having a bore 62 through which the terminal post 4 extends. The forward end 60 and rear end 63 of the sleeve 61 are both tapered to provide frustoconical surfaces.
The rear end 63 of the sleeve 61 extends a short distance into an opening 10 in the forward end 11 of the rear body 1, the length of the sleeve being such that the tip 3 and rear body 1 are separated from one another by a distance of about 8 mm. The rear body is of stainless steel and has a forward end 11 of cylindrical shape, the outer surface of which is formed with a screw-thread 1 2 by which the probe is retained in the boiler wall 2.
An axial bore 1 3 extends through the rear body 1, the forward end of the bore being enlarged to form the opening 10 and tapering to the smallerdiameter major portion 14 of the bore via a frustoconical, tapered sealing surface 1 5.
A second sealing washer 52 identical to the first washer 51 is located in the bore 13, sandwiched between the rear end surface 63 of the insulative sleeve 61 and the sealing surface 15 of the rear body 1.
The rear end 1 7 of the body 1 is of increased external diameter, its rear face being provided with a shallow recess 18 that forms the rear part of the bore 13. In the recess 1 8 there is located a stainless-steel disc spring 70 of the well-known kind made by Belleville Springs Limited. The spring 70 is shown in more detail, in its natural state, in Figure 2, and can be seen to comprise a circular disc having a central circular aperture 71, the disc having a frusto-conical surface. When the spring 70 is compressed axially between two members it is flattened out to an extent depending on the compression force, and the resilience of the spring 70 causes it to exert an axial force tending to separate the two members.
In the present invention, the spring 70 is clamped in the recess 1 8 between the rear body 1 and a spacer member 80. The spacer member 80 is a cylindrical block of alumina that has a central bore 81 through which the terminal post 4 extends. The forward end of the spacer member 80 has a short, reduced diameter projecting nose 82 that extends within the aperture 71 in the disc spring 70. The length of the nose 82 is about half the thickness of the disc spring, thereby ensuring that the nose does not contact the rear body 1.
The outer diameter of the spacer member 80 is less than that of the disc spring 70. The rear end of the spacer member 80 is contacted by a nickel plated, nickel-iron alloy washer 90 that is secured against the spacer member by a nut 91 screwed onto the rear threaded end of the terminal post 4.
The rear end of the nut is covered by a metal cap 92.
The probe is assembled by screwing the electrode tip 3 onto the forward end of the terminal post 4 and then threading onto the post the sealing washer 51, the sleeve 61, the washer 52, the rear body 1, the disc spring 70, the spacer member 80 and the washer 90. The probe so far assembled is then placed in a jig, which axially compresses together the tip 3 and the rear body 1 under a load of about 4000 Ibs, so that the sealing washers 51 and 52 are deformed into intimate contact with their abutting surfaces. The nut 91 is then screwed on, while the compression load is being applied, and tightened up to flatten the disc spring 70.The load is then released, the sealing of the two washers 51 and 52 being maintained by the resilience of the disc spring 70 which continues to exert a force equivalent to approximately 500 Ibs via the terminal post 4 which acts as a tension rod.
Because there is a continual force urging the tip 3 and rear body 1 together, it can be seen that the probe is relatively insensitive to thermal expansion effects. For example, assuming the coefficient of thermal expansion of the terminal post 4 to be greater than that of the insulative sleeve 61, heating of the probe would normally cause a greater expansion of the post than the sleeve tending to produce a separation of the sealing surfaces between the tip 3, the sleeve and the rear body. However, in the present invention, the force exerted by the disc spring 70 acts to maintain these parts together, thereby preventing any degradation in the integrity of the seal.
Since there is no requirement for the components of the probe to be thermally matched to one another, this allows a greater freedom in the selection of materials for any particular application. Thus, materials may be chosen which are resistant to corrosion, or have other desired properties, without problems due to differential thermal expansion.
It will be appreciated that other resilient members could be used to apply the axial compression leading on the sealing surfaces, and that the invention is not restricted to the use of disc springs. The invention finds application in other devices where an effective seal is required over a wide temperature range. In this respect the invention could be used, for example, in pressure or temperature probes or in spark plugs and other igniters.

Claims (16)

1. A seal arrangement comprising a first body, a second body arranged axially with said first body and having an axial bore therethrough, sealing means interposed between said first and second bodies, a tension member connected with said first body and extending through said second body, and resilient means interposed between said second body and said tension member such as to apply compression to said sealing means between said first and second bodies.
2. A seal arrangement according to Claim 1, wherein said resilient means includes a disc spring.
3. A seal arrangement according to claim 2, wherein said disc spring is of substantially frustoconical shape.
4. A seal arrangement according to any one of the preceding claims, wherein said tension member includes a rod having a screw-threaded portion, and a nut threaded on said portion, and wherein said resilient means embraces said rod and is interposed between said nut and said second body.
5. A seal arrangement according to any one of the preceding claims, wherein said sealing means includes a sealing ring.
6. A seal arrangement according to Claim 5, wherein said sealing means comprises a sleeve that extends around said tension member, a first sealing ring interposed between one end of said sleeve and said first body, and a second sealing ring interposed between the other end of said sleeve and said second body.
7. A seal arrangement according to Claim 6, wherein said sleeve has a tapered end that conforms with a tapered recess in said first or second body.
8. A seal arrangement according to Claim 7, wherein both ends of said sleeve are tapered and conform with respective tapered recesses in said first and second bodies.
9. A seal arrangement according to any one of Claims 5 to 8, wherein the or each sealing ring is of copper.
10. A seal arrangement according to any one of the preceding claims, wherein said first and second bodies and said tension member are of electrically-conductive material, wherein said sealing means includes an electrically-insulative member, and wherein said tension member is electrically insulated from said second body.
11. A seal arrangement according to Claim 10, including an electrically-insulative member located intermediate said second body and said tension member.
12. A seal arrangement according to any one of the preceding claims, wherein said second body is shaped for mounting in an aperture through the wall of a boiler.
13. A seal arrangement substantially as hereinbefore described with reference to the accompanying drawing.
14. A water-level sensing probe including a seal arrangement according to any one of the preceding claims.
1 5. A water-level sensing probe substantially as hereinbefore described with reference to the accompanying drawing.
16. Any novel feature or combination of features described herein.
GB08312706A 1982-05-28 1983-05-09 Sealing arrangements Expired GB2121125B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08312706A GB2121125B (en) 1982-05-28 1983-05-09 Sealing arrangements

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8215719 1982-05-28
GB08312706A GB2121125B (en) 1982-05-28 1983-05-09 Sealing arrangements

Publications (3)

Publication Number Publication Date
GB8312706D0 GB8312706D0 (en) 1983-06-15
GB2121125A true GB2121125A (en) 1983-12-14
GB2121125B GB2121125B (en) 1985-11-13

Family

ID=26282985

Family Applications (1)

Application Number Title Priority Date Filing Date
GB08312706A Expired GB2121125B (en) 1982-05-28 1983-05-09 Sealing arrangements

Country Status (1)

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GB (1) GB2121125B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102691795A (en) * 2012-06-08 2012-09-26 清华大学 Intelligent sealing ring applicable to ocean current generation
CN105697186A (en) * 2016-01-14 2016-06-22 安徽江淮汽车股份有限公司 Sealing device for oil level gauge hole of engine

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB414892A (en) * 1932-07-13 1934-08-16 Asea Ab Improvements relating to insulator bushings for the electrodes in electric gas or vapour discharge devices
GB1223521A (en) * 1968-04-22 1971-02-24 Sybron Corp Separable blade agitator
GB2007041A (en) * 1977-09-15 1979-05-10 Atomic Energy Authority Uk Improvements in electric cable gland seals
GB2072769A (en) * 1980-03-27 1981-10-07 Gerdts Gustav F Gmbh Co Kg Probe for monitoring liquids
GB1602989A (en) * 1977-11-30 1981-11-18 Metex Corp Exhaust seal

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB414892A (en) * 1932-07-13 1934-08-16 Asea Ab Improvements relating to insulator bushings for the electrodes in electric gas or vapour discharge devices
GB1223521A (en) * 1968-04-22 1971-02-24 Sybron Corp Separable blade agitator
GB2007041A (en) * 1977-09-15 1979-05-10 Atomic Energy Authority Uk Improvements in electric cable gland seals
GB1602989A (en) * 1977-11-30 1981-11-18 Metex Corp Exhaust seal
GB2072769A (en) * 1980-03-27 1981-10-07 Gerdts Gustav F Gmbh Co Kg Probe for monitoring liquids

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102691795A (en) * 2012-06-08 2012-09-26 清华大学 Intelligent sealing ring applicable to ocean current generation
CN102691795B (en) * 2012-06-08 2015-05-20 清华大学 Intelligent sealing ring applicable to ocean current generation
CN105697186A (en) * 2016-01-14 2016-06-22 安徽江淮汽车股份有限公司 Sealing device for oil level gauge hole of engine

Also Published As

Publication number Publication date
GB8312706D0 (en) 1983-06-15
GB2121125B (en) 1985-11-13

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PCNP Patent ceased through non-payment of renewal fee