CA2177431A1 - Valve stem gas leak detector - Google Patents
Valve stem gas leak detectorInfo
- Publication number
- CA2177431A1 CA2177431A1 CA002177431A CA2177431A CA2177431A1 CA 2177431 A1 CA2177431 A1 CA 2177431A1 CA 002177431 A CA002177431 A CA 002177431A CA 2177431 A CA2177431 A CA 2177431A CA 2177431 A1 CA2177431 A1 CA 2177431A1
- Authority
- CA
- Canada
- Prior art keywords
- valve stem
- segments
- gas
- enclosure
- valve
- 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.)
- Abandoned
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
- F16K37/00—Special means in or on valves or other cut-off apparatus for indicating or recording operation thereof, or for enabling an alarm to be given
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
- F16K41/00—Spindle sealings
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
Abstract
A valve stem gas leak detector configured to surround the stem of a possibly leaking gas flow line valve and provide for external monitoring equipment an electrical resistance related to the amount of gas leakage occurring around the valve stem. Such a gas leak detector, termable a ring sensor, is formed in interengageable, generally semicylindrical segments for ease of installation around and removal from the valve stem, with one or both of each such segments having an interiorly arranged layer of gas sensor particulate material, and with interengaging connector/conductor pins across which the electrical resistance of one or both gas sensor material layers can be measured with the ring sensor in place on the valve stem.
Description
~ 2t7743~
V~1VE STEM GP S LEI~K DETECTOR
BACKGROUND OF TEIE ~NVENTION
Field of the Inyeation This invention relates to hydrocarbon gas sensors and 5 more particularly to such gas sensors designed to monitor the presence of hydrocarbon gas and in particular hydrocarbon gas leakage from the valve stem of a valYe in a gas flow line such as found in petrochemical and petroleum ref ineries and the like.
Backqround of the Invention There is need as a matter of storage efficiency and environmental protection for valving as used in petroleum a~d petrochemical lines ana the like to have incorporated 15 therewith sensing mechanism by which leakaqe of gas from the valving czrn be monitored on a continuing basis so that gas leakage is promptly detectable when it occurs and can be corrected.
Sensors and sensor materials responsive to the 20 presence of even minute amounts of hydrocarbon gases are known such as disclosed in Dolan U.S. Patents 3,045,198, 4,224,595 and 4,23~,~21, for example. such gas sensors in general are comprised of electrically conductive adsorbent particles embedded in a resilient supporting substrate and are typically in cylindrical form such as shown in FIG. 4 of U S. Patent 3,045,195. Typically, in such sensors, the substrate is comprised of a resilient material such as rubber or silicone and the electro~onductive particles are . ~:
S selected frorn the group consisting of platinum, platinum black, aluminum, silver, gold, tantalum, carbon, or any other well-known electrically conductive particles and can comprise particles of various sizes and mixtures of such particles. However, as presently known, such gas sensors 10 are difficult and inefficient to use to rletect hydrocarbon gas leakage in the vicinity of the stem of a petrochemical or like valve because~a conventional sensor, in present form at least, even when placed next to a valve stem, is adjacent to o~ly a small portion of the valve stem surface and 15 exposed to only a small portion of the escaping gas if such gas is present.
Summary of the Invention It is an ob-j~ct and feature of the pre~i~nt invention 20 to provide an efficient gas leak detectox, for use in conjunction with petrochemical and petroleum refinery flow line valves and the li~ce, which comprises a generally cylindrical enclosure surrounding the stem of a valve being monitored for escaping gas, which can be readily installed 25 and removed from the valve stem, which is non-powered, which is economical to manufacture and is durable during use, which can be prograInmed on an individualized basis for ready identification in connection with any gas lealcage around the given valve stem with which it is so identified, and which 5 can be fabricated to respond sensitively to a variety of hydrocarbon gases.
These and other ob jects, features and advantages of ~ . _ valve stem gas leak detectors according to the present invention will be apparent from the following description 10 and accompanying illustration of a typical embodiment thereof .
BRIEF DESCRIPTION OF T~3E DRAWINGS
FIG. 1 is an isometric view of a petrochemical valve .
15 and a porti~n of the associated lineage, shown in phantom~
with a gas leak detector according to the present invention installed around the stem of the valve.
FIG. 2 is an exploded view on an enlarged scale of an iso.~etric showing of a valve st~T. portion with sensor 20 segments and shield segments shown in exploded form to illustrate the specific constructional nature thereof and _~
the manner of assembly with reference to a valve stem.
FIG. 3 is a top plan view on a further enlarged scale of the gas sensor segments and ~hieldsegments according to 25 the present invention, shown in an assembled condition with -- 3 -- .
` ~ 21 7743 ~
respect to the valve stem, with the stem shown in phantom in lateral cross=sections.
FIG. 4 is a view in axial cross section of the sensor ~ =
segments and shield segments shown in FIG. 3, taken S substantially along line 4-4 thereof.
FIG. 5 is a bottom view taken in lateral cross-section of the sensor segments with the shield segments removed for clarity of showing of the nature of the sensor surfaces.
10 Description of the Preferred Embodiment . = ~ . . . .
FIG. 1 shows a typical cQnventional gas flow line valve, generally designated V, as used in petrochemical and petroleum r~f inery flow systems, for example. The valve V
as shown comprises a valve stem S around which there is a 15 packing gland P which, in such valves, through wear and the like, can become worn and permit substantial leakage of hydrocarbon gas contained in the system to occur around the stem S. To monitor the valve V for gas leakage around the st~m S, t~.e present invention ir the embodiment illustrated 2 0 provides a gas sensor generally indicated at 10 which is placed around the valve stem S above the packing gland P and forms a ring-like generally cylindrical enclosure around the valve stem as shown in FIG. 1, closely surrounding the stem S immediately above the packing gland P. ~he gas sensor 10 25 contains one or more layers of gas sensing materials -the valve stem S, the interior su~face of the generally cylindrical enclosure, and is what may also be termed a ring sensor, with externally placed electrical conductors or contacts engageable by external resistance measuring 5 equipment (not shown ~ for monitaring the electrical resistance of said one or more gas sensing materials.
FIG. 2 discloses the gas sensor 10 shown in FIG. 1 in an exploded view with its gas sensQr segments and shield segments separated radially from a va~ve stem S and 10 separated axially with respect to each other. Specifically, gas sensor segments 12, 14 are shown in axial relation with respect to respective shield segments 16, 18. Each of the sensor segments 12, 14 is generally semi-cylindrical in conf iguration with segment 12 having circumferentially 15 extending portiDns 20, 22 which circumferentially overlap similar circumferentially extending portions 24, 26 OL
segment 14 when the two are assembled together (FIGS. 3 and _ 4 ) . The segments 12, 14 when so assembled are held together by the lower ends o~ steel connector/conductor pins 28, 30 20 whicb are positioned in respective jacks or sleeves 32, 34 - -in segment 14.
One or both of the respective inner surfaces 36, 38 have an electrically conductive gas sensor material layer 40, 42 coated thereon, such as disclosed in Dolan U.s.
25 Patent 4,224,595, ~or example, which material layer 40, 42 is responsive to the presence of even minute amountS of hydrocarbon gases and which layers 40, 42 may be comprised of either the same material or of dif~erent gas sensor materiaLs. If different mate~rials, as will be recognized, 5 one material layer 40 or 42 can be responsive to a different order of hydrocarbon gas concentr,ation or a differ~nt type of hydrocarbPn gas than the other, if desired. To provide a measurable output from the one or both gas sensor material layers 40, 42, the material layer 40 is in electrical 10 conductive relationship with and has electrical continuity with the connector pins 28, 30 by means of silver paint 41 and the material layer 42 is in electricall y conductive relationship with the metallic jacks or sleeves 32, 34 by means of silver paint 43 (FIGS. 4 and 5).
As will be apparent, the electroconductive layers 40, 42 are electrically connected in parallel across the pins 28, 30 and these pins are externally exposed when the segments 12, 14 are in assembled condition around a valve stem S ~FIGS. 1 and 3) so as to be ~ngageable by resi-tance 20 measuring equipment for monitoring the resistance of said one or more gas sensor materials and consequently a gas leakage condition around the valve stem S if such 1 eakage is o ccur r ing .
As a specif ic example of advantageous use of dif ferent 25 gas sensor materials in the respective layers 40, 42 on the -interior surfaces 36, 38 of the enclosure ormed by the ` ~ 2 1 7743 1 seni-cylindrical s~gments 12, 14, and utiliz ing graphite particles in one layer 40 and silver particles in the other ==:
layer 42 in a gas sensor designed for detection of naptha gas, the nominal resistance of the respective layers 40, 42 S in the absence of naptha gas (0 parts per 1,000,000) is respectively about 700 ohms and about 2 ohms, which will give a resistance reading of 2 ohms at the pins 28, 30 because the layers 40, 42 are connected in parallel across the pins 28, 30. When successive readings are compared for 10 a ring sensor utilizing a graphite particle layer 40 alone, versus a ring sensor utilizing a silver particle layer 42 in parallel with a graphite layer 40, the readings are 1400 ohms and 6 ohms for Z00 parts per 1,000,000 naptha gas, 8;00 ohms and 13 ohms for 40Q parts per 1,000,000 naptha gas, 12,000 ohms and 200 ohms for 600 parts naptha gas per 1,000,000, 30,000 ohms and 1200 ohms for a naptha gas concentration of 800 parts per 1,000,000, ~60,000 and 120,000 ohms for a naptha gas present in the amount of 1000 parts peL l,OOO,O00, ~nd 1 megohm and 1 megohm for naptha gas present in the an amount of 1200 parts per 1,000,000 sy the use of the respectively different makeup in the gas sensor layers 40, 42 the range of sensitivity of the gas sensor i5 extended, speci~ically in the lower coLlcentrations in this instance.
P.s earlier indicated, various sensor particle sizes and sensor particle mixtures according to the aforementioned Dolan patents and otherwise known in the art can be utilized in the one or more gas sensor material layers 40, 42 to adapt sensors according to~ the present invention to usages for monitoring a wide variety of hydrocarbon, i. e. organic, gases such as gasoline, diesel, naptha, ethers, h:eytones, halogenated hydrocarbons and the like The respective sensor segments 12, 14 have a relatively increased overall thickness in the upper portions thereof and are provided with respective series Q holes, __ certain of which are indicated at 44, 46, so that the net wall thickness of the segments, considered cross-sectisnally is approximately the same throughout. These segments are preferably fabricated of molded plastic, such as PVC, and the uniformity of wall thickness throughout facilitates the f abr icati4n thereof .
To aid in the protection of the sensor ~material layers 40, 42 during handling of the sensor segments 12, 14, the form of gas sensor 10 iLlustrated includes substantially semi-cylindrical shield segments 16, 18 which have respective external, radially extending ledges 48, S0, each with resF2ctive downwal~dly and axially extending peg-like projections, certain of which are indicated at 52, 54 which fit within respective holes 44, 46 in the segments 12, 14 and snugly substantially surround the valve stem S. In practice, the respective shield segments 16, 18 are assembled with and ~onded as by adhesive onto the respective sensor segments 12, 14 before assembly o the segments 12, 14 around the valve steln S. With such preassembly of a _ given shield segment on its associated sensor segment the shield segment in its lower portlon extending axially and substantially coextensively with and in spaced relation to S the associated sensor material layer and serves to mechanically protect the sensor material layer from physical contact by a worker installing the sensor and from contact with the valve stem or portions of the valve packing gland during assembly of the segments around the stem.
The shield segments also i~l~nction as a grease guard to minimi2e possible fouling o~ the gas sensor layers with grease flom the valve stem and valve packing gland.
~ hen the sensor segments and associated shield segments are in assembled form around the valve stem S, the 15 desired d~sign parameter with respect to clearance of the shield segments around the stem is to leave the segments somewhat loose relative to the stem (with about . 025 inch clearance) to prevent gas buildup within the sensor s egmen ts .
~s will be recongized with respect to the sensor materials responsiYe to minute quantities of hydrocarbon gas in terms of change in electrical resistance across adsorptive particles, with a given type of material, for example a layer of carbon particles and with no hydrocarbon gas leak, the resistance o~ a ~iven sensor material layer - _ g _ .
~ ` ~
can be about 700 ohms. Then, if a leak occurs, such as on the order of ~ 3_mm per minute of hydrocarbon vapor escape rate, the electrical resistance of the gas sensor material layer can increase to about 100, OQ0 ohms, inaicating of ~ -5 course that there is substantial valve leakage needing valve packing replacement or other valve repair.
~ s will be apparent, valve stem gas leak detectors acco~ding to the invention can be made in various sizes for use with various diameter yalve stems 3nd one advantage of 10 fabrication with separate sensor segments ~e. g. segments 10, 12 ) and shield segments (e. g. segments 16, 18 ) is that a given pair of gas sensor segments ~e.g. 10, 12) can be used with a range o~ sizes of valve stems by providing an inventory of a plurality of sizes of shield segments ~e.g.
lS 1~, 18 ) which are of cour5e cheaper and simpler to fabricate than the gas sensDr segments.
In use, gas sensor segments in ring form according to the present invention can be read with any ohmmeter in a Qne second response time, as by momentary connection o~ the 20 meter probes to the connector~conductor pins ~e.g. 28, 30) giving an instantaneous reading directly rel~ted to hydrocarbon gas concentration around the valve stem. Such ring sensors do not interfere with valve operation, require no valve disassembly, and are installable quickLy and also 25 quickly removable for other valve maintenance The gas sensor technology involved is in widespread use for petroleum leak detection in hundreds of service stations and __ elsewhere, and is intrinsically safe. The ring sensOr of the invention is pro jected as having a f ield liie of ten 5 years and more and is not affected by rain, humidity, wind, dust, temperature extremes, paint, or lubrication grease.
In the form of sensor segments shown, one of the segments 12 is provided with an R~ID identifier 56, suitably of a type known per se such as an OF 12-Series Read Only 1~ Tag, readable by a Balogh Transceiver, and availabie from the Balogh Company of Ann Arbor, MI, to provide electronic identif ication essentially simultaneously with a hydrocarbon gas concentration responsive resistance reading.
P.lternatively, individual gas sensor and gas valve identif ication can be provided by installing with a given ~ ~ =
valve stem ring sensor a touch memcry in electrically =_ parallel relation to the gas sensor material, as by use of a touch memory such as Dallas semiconductor DS 2502 available from Dallas Semiconductor, Inc. of ~)allas, Texas. Such a 20 touch memory can be written to and read in a conventional manner to provide a means for individually identifying a particular valve stem and its sensor electronically. A
blocking diode is placed in circuit in parallel arrangement with a given gas sensor material, ( i.e. across pins 16, 18, 25 for example). Then, with a positive bias applied across the ( material a monitor receives an identi~ication in~ut rom the semiconductor. By reversing the bias across the semiconductor and the gas sensor material, the resistance of the gas sensor material can then be measured, the blocking S diode in such second reading situation having a high impedance and serving to electrical~y remove the identifier semiconductor from the sensor measuring circuit.
From the foregoing further modif ications and adaptations and changes can occur to those skilled in the 10 art, consistent with the nature of the invention as def ined in the following claims.
V~1VE STEM GP S LEI~K DETECTOR
BACKGROUND OF TEIE ~NVENTION
Field of the Inyeation This invention relates to hydrocarbon gas sensors and 5 more particularly to such gas sensors designed to monitor the presence of hydrocarbon gas and in particular hydrocarbon gas leakage from the valve stem of a valYe in a gas flow line such as found in petrochemical and petroleum ref ineries and the like.
Backqround of the Invention There is need as a matter of storage efficiency and environmental protection for valving as used in petroleum a~d petrochemical lines ana the like to have incorporated 15 therewith sensing mechanism by which leakaqe of gas from the valving czrn be monitored on a continuing basis so that gas leakage is promptly detectable when it occurs and can be corrected.
Sensors and sensor materials responsive to the 20 presence of even minute amounts of hydrocarbon gases are known such as disclosed in Dolan U.S. Patents 3,045,198, 4,224,595 and 4,23~,~21, for example. such gas sensors in general are comprised of electrically conductive adsorbent particles embedded in a resilient supporting substrate and are typically in cylindrical form such as shown in FIG. 4 of U S. Patent 3,045,195. Typically, in such sensors, the substrate is comprised of a resilient material such as rubber or silicone and the electro~onductive particles are . ~:
S selected frorn the group consisting of platinum, platinum black, aluminum, silver, gold, tantalum, carbon, or any other well-known electrically conductive particles and can comprise particles of various sizes and mixtures of such particles. However, as presently known, such gas sensors 10 are difficult and inefficient to use to rletect hydrocarbon gas leakage in the vicinity of the stem of a petrochemical or like valve because~a conventional sensor, in present form at least, even when placed next to a valve stem, is adjacent to o~ly a small portion of the valve stem surface and 15 exposed to only a small portion of the escaping gas if such gas is present.
Summary of the Invention It is an ob-j~ct and feature of the pre~i~nt invention 20 to provide an efficient gas leak detectox, for use in conjunction with petrochemical and petroleum refinery flow line valves and the li~ce, which comprises a generally cylindrical enclosure surrounding the stem of a valve being monitored for escaping gas, which can be readily installed 25 and removed from the valve stem, which is non-powered, which is economical to manufacture and is durable during use, which can be prograInmed on an individualized basis for ready identification in connection with any gas lealcage around the given valve stem with which it is so identified, and which 5 can be fabricated to respond sensitively to a variety of hydrocarbon gases.
These and other ob jects, features and advantages of ~ . _ valve stem gas leak detectors according to the present invention will be apparent from the following description 10 and accompanying illustration of a typical embodiment thereof .
BRIEF DESCRIPTION OF T~3E DRAWINGS
FIG. 1 is an isometric view of a petrochemical valve .
15 and a porti~n of the associated lineage, shown in phantom~
with a gas leak detector according to the present invention installed around the stem of the valve.
FIG. 2 is an exploded view on an enlarged scale of an iso.~etric showing of a valve st~T. portion with sensor 20 segments and shield segments shown in exploded form to illustrate the specific constructional nature thereof and _~
the manner of assembly with reference to a valve stem.
FIG. 3 is a top plan view on a further enlarged scale of the gas sensor segments and ~hieldsegments according to 25 the present invention, shown in an assembled condition with -- 3 -- .
` ~ 21 7743 ~
respect to the valve stem, with the stem shown in phantom in lateral cross=sections.
FIG. 4 is a view in axial cross section of the sensor ~ =
segments and shield segments shown in FIG. 3, taken S substantially along line 4-4 thereof.
FIG. 5 is a bottom view taken in lateral cross-section of the sensor segments with the shield segments removed for clarity of showing of the nature of the sensor surfaces.
10 Description of the Preferred Embodiment . = ~ . . . .
FIG. 1 shows a typical cQnventional gas flow line valve, generally designated V, as used in petrochemical and petroleum r~f inery flow systems, for example. The valve V
as shown comprises a valve stem S around which there is a 15 packing gland P which, in such valves, through wear and the like, can become worn and permit substantial leakage of hydrocarbon gas contained in the system to occur around the stem S. To monitor the valve V for gas leakage around the st~m S, t~.e present invention ir the embodiment illustrated 2 0 provides a gas sensor generally indicated at 10 which is placed around the valve stem S above the packing gland P and forms a ring-like generally cylindrical enclosure around the valve stem as shown in FIG. 1, closely surrounding the stem S immediately above the packing gland P. ~he gas sensor 10 25 contains one or more layers of gas sensing materials -the valve stem S, the interior su~face of the generally cylindrical enclosure, and is what may also be termed a ring sensor, with externally placed electrical conductors or contacts engageable by external resistance measuring 5 equipment (not shown ~ for monitaring the electrical resistance of said one or more gas sensing materials.
FIG. 2 discloses the gas sensor 10 shown in FIG. 1 in an exploded view with its gas sensQr segments and shield segments separated radially from a va~ve stem S and 10 separated axially with respect to each other. Specifically, gas sensor segments 12, 14 are shown in axial relation with respect to respective shield segments 16, 18. Each of the sensor segments 12, 14 is generally semi-cylindrical in conf iguration with segment 12 having circumferentially 15 extending portiDns 20, 22 which circumferentially overlap similar circumferentially extending portions 24, 26 OL
segment 14 when the two are assembled together (FIGS. 3 and _ 4 ) . The segments 12, 14 when so assembled are held together by the lower ends o~ steel connector/conductor pins 28, 30 20 whicb are positioned in respective jacks or sleeves 32, 34 - -in segment 14.
One or both of the respective inner surfaces 36, 38 have an electrically conductive gas sensor material layer 40, 42 coated thereon, such as disclosed in Dolan U.s.
25 Patent 4,224,595, ~or example, which material layer 40, 42 is responsive to the presence of even minute amountS of hydrocarbon gases and which layers 40, 42 may be comprised of either the same material or of dif~erent gas sensor materiaLs. If different mate~rials, as will be recognized, 5 one material layer 40 or 42 can be responsive to a different order of hydrocarbon gas concentr,ation or a differ~nt type of hydrocarbPn gas than the other, if desired. To provide a measurable output from the one or both gas sensor material layers 40, 42, the material layer 40 is in electrical 10 conductive relationship with and has electrical continuity with the connector pins 28, 30 by means of silver paint 41 and the material layer 42 is in electricall y conductive relationship with the metallic jacks or sleeves 32, 34 by means of silver paint 43 (FIGS. 4 and 5).
As will be apparent, the electroconductive layers 40, 42 are electrically connected in parallel across the pins 28, 30 and these pins are externally exposed when the segments 12, 14 are in assembled condition around a valve stem S ~FIGS. 1 and 3) so as to be ~ngageable by resi-tance 20 measuring equipment for monitoring the resistance of said one or more gas sensor materials and consequently a gas leakage condition around the valve stem S if such 1 eakage is o ccur r ing .
As a specif ic example of advantageous use of dif ferent 25 gas sensor materials in the respective layers 40, 42 on the -interior surfaces 36, 38 of the enclosure ormed by the ` ~ 2 1 7743 1 seni-cylindrical s~gments 12, 14, and utiliz ing graphite particles in one layer 40 and silver particles in the other ==:
layer 42 in a gas sensor designed for detection of naptha gas, the nominal resistance of the respective layers 40, 42 S in the absence of naptha gas (0 parts per 1,000,000) is respectively about 700 ohms and about 2 ohms, which will give a resistance reading of 2 ohms at the pins 28, 30 because the layers 40, 42 are connected in parallel across the pins 28, 30. When successive readings are compared for 10 a ring sensor utilizing a graphite particle layer 40 alone, versus a ring sensor utilizing a silver particle layer 42 in parallel with a graphite layer 40, the readings are 1400 ohms and 6 ohms for Z00 parts per 1,000,000 naptha gas, 8;00 ohms and 13 ohms for 40Q parts per 1,000,000 naptha gas, 12,000 ohms and 200 ohms for 600 parts naptha gas per 1,000,000, 30,000 ohms and 1200 ohms for a naptha gas concentration of 800 parts per 1,000,000, ~60,000 and 120,000 ohms for a naptha gas present in the amount of 1000 parts peL l,OOO,O00, ~nd 1 megohm and 1 megohm for naptha gas present in the an amount of 1200 parts per 1,000,000 sy the use of the respectively different makeup in the gas sensor layers 40, 42 the range of sensitivity of the gas sensor i5 extended, speci~ically in the lower coLlcentrations in this instance.
P.s earlier indicated, various sensor particle sizes and sensor particle mixtures according to the aforementioned Dolan patents and otherwise known in the art can be utilized in the one or more gas sensor material layers 40, 42 to adapt sensors according to~ the present invention to usages for monitoring a wide variety of hydrocarbon, i. e. organic, gases such as gasoline, diesel, naptha, ethers, h:eytones, halogenated hydrocarbons and the like The respective sensor segments 12, 14 have a relatively increased overall thickness in the upper portions thereof and are provided with respective series Q holes, __ certain of which are indicated at 44, 46, so that the net wall thickness of the segments, considered cross-sectisnally is approximately the same throughout. These segments are preferably fabricated of molded plastic, such as PVC, and the uniformity of wall thickness throughout facilitates the f abr icati4n thereof .
To aid in the protection of the sensor ~material layers 40, 42 during handling of the sensor segments 12, 14, the form of gas sensor 10 iLlustrated includes substantially semi-cylindrical shield segments 16, 18 which have respective external, radially extending ledges 48, S0, each with resF2ctive downwal~dly and axially extending peg-like projections, certain of which are indicated at 52, 54 which fit within respective holes 44, 46 in the segments 12, 14 and snugly substantially surround the valve stem S. In practice, the respective shield segments 16, 18 are assembled with and ~onded as by adhesive onto the respective sensor segments 12, 14 before assembly o the segments 12, 14 around the valve steln S. With such preassembly of a _ given shield segment on its associated sensor segment the shield segment in its lower portlon extending axially and substantially coextensively with and in spaced relation to S the associated sensor material layer and serves to mechanically protect the sensor material layer from physical contact by a worker installing the sensor and from contact with the valve stem or portions of the valve packing gland during assembly of the segments around the stem.
The shield segments also i~l~nction as a grease guard to minimi2e possible fouling o~ the gas sensor layers with grease flom the valve stem and valve packing gland.
~ hen the sensor segments and associated shield segments are in assembled form around the valve stem S, the 15 desired d~sign parameter with respect to clearance of the shield segments around the stem is to leave the segments somewhat loose relative to the stem (with about . 025 inch clearance) to prevent gas buildup within the sensor s egmen ts .
~s will be recongized with respect to the sensor materials responsiYe to minute quantities of hydrocarbon gas in terms of change in electrical resistance across adsorptive particles, with a given type of material, for example a layer of carbon particles and with no hydrocarbon gas leak, the resistance o~ a ~iven sensor material layer - _ g _ .
~ ` ~
can be about 700 ohms. Then, if a leak occurs, such as on the order of ~ 3_mm per minute of hydrocarbon vapor escape rate, the electrical resistance of the gas sensor material layer can increase to about 100, OQ0 ohms, inaicating of ~ -5 course that there is substantial valve leakage needing valve packing replacement or other valve repair.
~ s will be apparent, valve stem gas leak detectors acco~ding to the invention can be made in various sizes for use with various diameter yalve stems 3nd one advantage of 10 fabrication with separate sensor segments ~e. g. segments 10, 12 ) and shield segments (e. g. segments 16, 18 ) is that a given pair of gas sensor segments ~e.g. 10, 12) can be used with a range o~ sizes of valve stems by providing an inventory of a plurality of sizes of shield segments ~e.g.
lS 1~, 18 ) which are of cour5e cheaper and simpler to fabricate than the gas sensDr segments.
In use, gas sensor segments in ring form according to the present invention can be read with any ohmmeter in a Qne second response time, as by momentary connection o~ the 20 meter probes to the connector~conductor pins ~e.g. 28, 30) giving an instantaneous reading directly rel~ted to hydrocarbon gas concentration around the valve stem. Such ring sensors do not interfere with valve operation, require no valve disassembly, and are installable quickLy and also 25 quickly removable for other valve maintenance The gas sensor technology involved is in widespread use for petroleum leak detection in hundreds of service stations and __ elsewhere, and is intrinsically safe. The ring sensOr of the invention is pro jected as having a f ield liie of ten 5 years and more and is not affected by rain, humidity, wind, dust, temperature extremes, paint, or lubrication grease.
In the form of sensor segments shown, one of the segments 12 is provided with an R~ID identifier 56, suitably of a type known per se such as an OF 12-Series Read Only 1~ Tag, readable by a Balogh Transceiver, and availabie from the Balogh Company of Ann Arbor, MI, to provide electronic identif ication essentially simultaneously with a hydrocarbon gas concentration responsive resistance reading.
P.lternatively, individual gas sensor and gas valve identif ication can be provided by installing with a given ~ ~ =
valve stem ring sensor a touch memcry in electrically =_ parallel relation to the gas sensor material, as by use of a touch memory such as Dallas semiconductor DS 2502 available from Dallas Semiconductor, Inc. of ~)allas, Texas. Such a 20 touch memory can be written to and read in a conventional manner to provide a means for individually identifying a particular valve stem and its sensor electronically. A
blocking diode is placed in circuit in parallel arrangement with a given gas sensor material, ( i.e. across pins 16, 18, 25 for example). Then, with a positive bias applied across the ( material a monitor receives an identi~ication in~ut rom the semiconductor. By reversing the bias across the semiconductor and the gas sensor material, the resistance of the gas sensor material can then be measured, the blocking S diode in such second reading situation having a high impedance and serving to electrical~y remove the identifier semiconductor from the sensor measuring circuit.
From the foregoing further modif ications and adaptations and changes can occur to those skilled in the 10 art, consistent with the nature of the invention as def ined in the following claims.
Claims (11)
1. A valve stem gas leak sensor comprising a generally cylindrical enclosure closely surrounding the valve stem of a possibly leaking petroleum flow line valve, said cylindrical enclosure being situated adjacent the valve packing gland and being interiorly open around said valve stem, a hydrocarbon gas sensing material layer on the interior surface of said enclosure, and electrical conductor means electrically connected to said hydrocarbon gas sensing material with portions of said conductor means exposed exteriorly of said enclosure so as to be contactable by external monitoring equipment which, by sensing a change in the electrical resistance of said gas sensing material caused by adsorption of hydrocarbon gas into the sensing material layer, provides an indication of there being hydrocarbon gas present interiorly of said enclosure, said generally cylindrical enclosure comprising two substantially semi-cylindrical segments, each having mating surfaces designed to mate together in a complementary manner with metallic pins in one segment fitting in jacks in the other segment which are arranged to hold said segments together around the valve stem.
2. A valve stem gas leak sensor according to claim 1, wherein said metallic pins also serve as said conductor means.
3. A valve stem gas leak sensor according to claim 2, wherein substantially semi-cylindrical shield segment means are mounted around the valve stem such that said shield segment means are arranged interiorly of said enclosure segments, and also arranged in inwardly spaced relation with respect to said hydrocarbon gas sensing material layer.
4. A gas leak detector for use in conjunction with the valve stem of a valve in a petroleum flow line such as found in petrochemical and petroleum refineries and the like, said detector comprising:
two substantially semi-cylindrical segments, each segment having circumferentially extending portions overlapping similar portions on the other segment, said segments when assembled together in an overlapping manner having a inner bore of a diameter slightly larger than the diameter of the valve stem around which they are designed for mutual assembly on and said segments when so assembled having within one or more circumferentially recessed inner portions of said inner bore one or more deposits of gas sensor material layers the electrical resistance of which is responsive to and varied by the presence and adsorption of any hydrocarbon gas escaping at the valve stem on which the segments are assembled;
a pair of axially extending connector pins interconnecting said segments, said pins being in electrically conductive engagement with said one or more deposits of gas sensor materials and extending externally of the assembled segments so as to be engageable by resistance measuring equipment for monitoring the resistance of said one or more deposits of gas sensor materials and consequently indicating any gas leakage condition around the valve stem on which the segments are installed.
two substantially semi-cylindrical segments, each segment having circumferentially extending portions overlapping similar portions on the other segment, said segments when assembled together in an overlapping manner having a inner bore of a diameter slightly larger than the diameter of the valve stem around which they are designed for mutual assembly on and said segments when so assembled having within one or more circumferentially recessed inner portions of said inner bore one or more deposits of gas sensor material layers the electrical resistance of which is responsive to and varied by the presence and adsorption of any hydrocarbon gas escaping at the valve stem on which the segments are assembled;
a pair of axially extending connector pins interconnecting said segments, said pins being in electrically conductive engagement with said one or more deposits of gas sensor materials and extending externally of the assembled segments so as to be engageable by resistance measuring equipment for monitoring the resistance of said one or more deposits of gas sensor materials and consequently indicating any gas leakage condition around the valve stem on which the segments are installed.
5. A gas leak detector according to claim 4, further comprising a pair of semi-cylindrical, thin-walled guards axially insertable between the stem of the valve on which said two substantially semi-circular segments are assembled and the inner bore of said segments, said guards in such position serving to protect the one or more sensor material layers within the segments from physical damage.
6. A valve stem gas leak sensor comprising an enclosure closely surrounding the valve stem of a possibly leaking petroleum flow line valve, said enclosure being situated adjacent the valve packing gland and being interiorly open around said valve stem, a hydrocarbon gas sensing material layer on the interior surface of said enclosure, and electrical conductor means electrically connected to said hydrocarbon gas sensing material with portions of said conductor means exposed exteriorly of said enclosure so as to be contactable by external monitoring equipment which, by sensing a change in the electrical resistance of said gas sensing material caused by absorption of hydrocarbon gas into the sensing material layer, provides an indication of there being hydrocarbon gas present interiorly of said enclosure, said enclosure comprising two separable segments having circumferentially extending portions overlapping similar portions on the other segment with said segments configured, when assembled together in an overlapping manner, to provide an inner bore of a diameter slightly larger than the diameter of the valve stem around which they are designed for mutual assembly.
7. A valve stem gas leak sensor according to claim 6, wherein said segments comprise mechanically interengageable parts which are assemblable and separable by relative movement axially of the valve stem, and which are configured to hold said segments together around the valve stem when interengaged.
8. A valve stem gas leak sensor according to claim 7, wherein said interengageable parts include are metallic pins in one segment and jacks in the other segment in which the pins interfit.
9. A valve stem gas leak sensor according to claim 6, comprising shield segments mounted around the valve stem and arranged interiorly of said enclosure segments in inwardly spaced relation with respect to said hydrocarbon gas sensing material layer.
10. A valve stem gas leak sensor according to claim 6, wherein said inner bore of said enclosure provides a somewhat loose spacing relative to the valve stem surrounded by the enclosure so as to prevent gas build-up within the enclosure.
11. A gas leak detector according to claim 10, where spacing is about .025 inch.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/465,819 | 1995-06-06 | ||
| US08/465,819 US5594162A (en) | 1995-06-06 | 1995-06-06 | Valve stem gas leak detector |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2177431A1 true CA2177431A1 (en) | 1996-12-07 |
Family
ID=23849288
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002177431A Abandoned CA2177431A1 (en) | 1995-06-06 | 1996-05-27 | Valve stem gas leak detector |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US5594162A (en) |
| CA (1) | CA2177431A1 (en) |
| GB (1) | GB2308449A (en) |
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| US6433694B1 (en) * | 1998-03-26 | 2002-08-13 | Adsistor Technology Inc. | Sensor having improved desorption times and related control circuitry |
| US6102085A (en) * | 1998-11-09 | 2000-08-15 | Marconi Commerce Systems, Inc. | Hydrocarbon vapor sensing |
| US6879876B2 (en) * | 2001-06-13 | 2005-04-12 | Advanced Technology Materials, Inc. | Liquid handling system with electronic information storage |
| US7702418B2 (en) * | 2001-06-13 | 2010-04-20 | Advanced Technology Materials, Inc. | Secure reader system |
| CA2416275A1 (en) * | 2003-01-08 | 2004-07-08 | Hydro Quebec | Motorized band for measuring the thickness of a pipe |
| US6840086B2 (en) | 2003-03-06 | 2005-01-11 | Cincinnati Test Systems, Inc. | Method and apparatus for detecting leaks |
| US7051578B2 (en) * | 2003-03-06 | 2006-05-30 | Cincinnati Test Systems, Inc. | Method and apparatus for detecting a gas |
| US20050224523A1 (en) * | 2004-04-13 | 2005-10-13 | Advanced Technology Materials, Inc. | Liquid dispensing method and system with headspace gas removal |
| US20050279207A1 (en) * | 2004-06-16 | 2005-12-22 | Advanced Technology Materials, Inc. | Liquid delivery system |
| US7178385B2 (en) * | 2004-06-18 | 2007-02-20 | Cincinnati Test Systems, Inc. | Method and apparatus for detecting leaks |
| NZ533910A (en) | 2004-07-05 | 2007-02-23 | Tyco Flow Control Pacific Pty | Valve status monitoring |
| WO2007146892A2 (en) * | 2006-06-13 | 2007-12-21 | Advanced Technology Materials, Inc. | Liquid dispensing systems encompassing gas removal |
| WO2008011297A2 (en) | 2006-07-10 | 2008-01-24 | Advanced Technology Materials, Inc. | Systems and methods for managing material storage vessels having information storage elements |
| US7552643B2 (en) | 2006-12-08 | 2009-06-30 | Centre For Nuclear Energy Research (CNER) | Device and system for corrosion detection |
| CA2570710A1 (en) * | 2006-12-08 | 2008-06-08 | Centre For Nuclear Energy Research, Inc. | Device and system for corrosion detection |
| US20120048000A1 (en) | 2010-08-31 | 2012-03-01 | Joseph Kirzhner | Method and system to detect and measure piping fuel leak |
| NO345466B1 (en) * | 2019-06-12 | 2021-02-15 | Prosence As | Apparatus, system and method for detecting a leakage of a fluid |
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| US3045198A (en) * | 1959-12-11 | 1962-07-17 | James P Dolan | Detection device |
| US3938544A (en) * | 1974-05-28 | 1976-02-17 | Bernaerts Henry J | Valve with heat transport monitor for leakage determining rate |
| US4224585A (en) * | 1978-08-28 | 1980-09-23 | Reticon Corporation | Methods and apparatus for compensating for charge transfer inefficiency in imaging and other variable length charge transfer devices |
| US4466273A (en) * | 1978-10-23 | 1984-08-21 | Pillette Kibbie P | Leak detection system |
| US4237721A (en) * | 1978-12-11 | 1980-12-09 | Ads Systems, Inc. | Apparatus and method for detecting substances and for regulating current |
| US4562725A (en) * | 1982-07-31 | 1986-01-07 | Shimadzu Corporation | Moisture sensor and a process for the production thereof |
| US4601194A (en) * | 1983-01-18 | 1986-07-22 | Damco Testers, Inc. | Method and apparatus for leak testing of pipe |
| US4517828A (en) * | 1983-06-28 | 1985-05-21 | Damco Testers, Inc. | Apparatus for leak testing of pipe |
| US4573344A (en) * | 1984-06-19 | 1986-03-04 | Westinghouse Electric Corp. | Valve packing leakage monitoring device |
| WO1986000409A1 (en) * | 1984-06-21 | 1986-01-16 | Matsushita Electric Industrial Co., Ltd. | Humidity sensor |
| ATE86040T1 (en) * | 1985-06-12 | 1993-03-15 | Raychem Corp | HYDROCARBON SENSOR. |
| EP0311939A3 (en) * | 1987-10-12 | 1990-10-17 | Nihon Parkerizing Co., Ltd. | Humidity sensor |
| US4915816A (en) * | 1988-09-06 | 1990-04-10 | Parthasarathy Shakkottai | Polymer hygrometer for harsh environments |
| US4972867A (en) * | 1989-11-03 | 1990-11-27 | Ruesch J O | Valve stem seal leak protection and detection apparatus |
| JP2702279B2 (en) * | 1990-11-30 | 1998-01-21 | 新コスモス電機株式会社 | Gas detection element |
| US5263682A (en) * | 1992-03-17 | 1993-11-23 | Whitey Co. | Valve stem packing system |
| FR2688860B1 (en) * | 1992-03-20 | 1994-06-17 | Aerospatiale | WATERPROOF DRAINAGE MEMBER FOR HYDRAULIC CIRCUIT. |
| US5309752A (en) * | 1992-07-17 | 1994-05-10 | Praxair Technology, Inc. | Leakage measurement into a gas-charged collapsible container |
-
1995
- 1995-06-06 US US08/465,819 patent/US5594162A/en not_active Expired - Fee Related
-
1996
- 1996-05-21 GB GB9610583A patent/GB2308449A/en not_active Withdrawn
- 1996-05-27 CA CA002177431A patent/CA2177431A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| US5594162A (en) | 1997-01-14 |
| GB2308449A (en) | 1997-06-25 |
| GB9610583D0 (en) | 1996-07-31 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |