WO2008050936A1 - Fusible alloy for pressure relief devices - Google Patents
Fusible alloy for pressure relief devices Download PDFInfo
- Publication number
- WO2008050936A1 WO2008050936A1 PCT/KR2006/005825 KR2006005825W WO2008050936A1 WO 2008050936 A1 WO2008050936 A1 WO 2008050936A1 KR 2006005825 W KR2006005825 W KR 2006005825W WO 2008050936 A1 WO2008050936 A1 WO 2008050936A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- alloy
- prd
- fusible alloy
- fusible
- alloys
- Prior art date
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C11/00—Alloys based on lead
- C22C11/08—Alloys based on lead with antimony or bismuth as the next major constituent
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C30/00—Alloys containing less than 50% by weight of each constituent
- C22C30/04—Alloys containing less than 50% by weight of each constituent containing tin or lead
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C11/00—Alloys based on lead
- C22C11/08—Alloys based on lead with antimony or bismuth as the next major constituent
- C22C11/10—Alloys based on lead with antimony or bismuth as the next major constituent with tin
-
- 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
- F16K17/00—Safety valves; Equalising valves, e.g. pressure relief valves
- F16K17/36—Safety valves; Equalising valves, e.g. pressure relief valves actuated in consequence of extraneous circumstances, e.g. shock, change of position
- F16K17/38—Safety valves; Equalising valves, e.g. pressure relief valves actuated in consequence of extraneous circumstances, e.g. shock, change of position of excessive temperature
- F16K17/383—Safety valves; Equalising valves, e.g. pressure relief valves actuated in consequence of extraneous circumstances, e.g. shock, change of position of excessive temperature the valve comprising fusible, softening or meltable elements, e.g. used as link, blocking element, seal, closure plug
Definitions
- the present invention relates to a fusible alloy for pressure relief devices (PRDs), and more particularly, to a fusible alloy for PRD, which is appropriate for use according to the 110°C-grade standards and has excellent wettability upon melting.
- PRDs pressure relief devices
- Pressure relief devices are safety devices attached to gas cylinder valves in automobiles and the like, which devices play the role of preventing gas explosion by rapidly discharging gases inside the cylinder to the outside when the temperature of the ambient environment rises abnormally to above a specific temperature, such as at the time of fire.
- a conceptually ideal PRD is expected to completely cut off the outflow of gases up to a specific temperature, and when the specific temperature is reached, to discharge the entire amount of the gases within a short time.
- the European standards stipulate a use of alloys having a melting point acceptable for the 110°C-grade (110 ⁇ 10°C), to provide against safety accidents involving gas explosions.
- Fig. 1 shows photographs showing the wetting angles of the fusible alloy for PRD according to the present invention and of a conventional fusible alloy for PRD, as measured in a wettability test.
- Fig. 2 shows scanning electron microscopic (SEM) photographs of exemplary reinforcement materials used in the preparation of the fusible alloy according to the present invention.
- a quaternary fusible alloy for PRD comprising 29.0 to 33.0% by- weight of bismuth (Bi), 14.0 to 21.0% by weight of tin (Sn), 2.0 to 5.0% by weight of indium (In), and substantially lead (Pb) for the balance.
- the present invention chooses to use a quaternary alloy because the low-melting point alloying elements, namely, Pb, Bi, Sn and In, themselves have low melting points, and also because when these elements form a polynary alloy, the alloy may have a eutectic point, thus it being possible to render the melting point of the alloy even lower.
- the low-melting point alloying elements namely, Pb, Bi, Sn and In
- the alloy may have a eutectic point, thus it being possible to render the melting point of the alloy even lower.
- a Pb-Sn alloy which is a representative solder material
- an alloy of Pb with 61.9% of Sn has a melting point of 183 0 C at the eutectic point.
- the melting point of an alloy can be further lowered by increasing the number of alloying elements to systems of ternary, quaternary and the like.
- the results of thermodynamic calculations were used as the basis of the primary alloy designs for appropriate composition ratios of the alloying elements.
- the melting points of ternary, quaternary and quinary alloys of various compositions were predicted based on the calculations using thermodynamic data.
- a quaternary system of Bi-Sn-In-Pb that was considered to be an optimum was selected to constitute the alloy of the present invention, and the composition was determined to fall within a specific range through actual experimentation.
- the composition ratios of the alloy-constituting elements were determined to be ' 29.0 to 33.0% by weight for Bi, 14.0 to 21.0% by weight for Sn, 2.0 to 5.0% by weight of In, and substantially Pb for the balance. If the respective component elements are contained in the alloy of the invention in amounts beyond the above-described composition ranges, the melting point (in particular, the melting start point) may be lowered to below 100°C, thus causing the alloy to melt at a temperature below the critical temperature; or the melting point may be raised to above 120°C, thus inhibiting efficient discharge of gases at an appropriate temperature and subsequent prevention of safety accident such as gas explosion. Then, such alloys are deprived of the function as the 110°C-grade fusible alloys for PRD, and are undesirable.
- the properties that are necessary for an alloy to be used as a fusible alloy for PRD include melting point, wettability, PRD durability, and the like.
- composition ratios by weight were calculated, and the elements were respectively weighed. Then, the elements were mixed and melted together to form fusible alloys, and then, mother alloy ingots of the respective compositions, each weighing about 1 kg, were prepared. Subsequently, each fusible alloy was placed on a substrate made of brass and maintained at a desired temperature for 10 minutes using glycerin solution as a heating medium, and then, the presence or absence of melting of the fusible alloy was verified.
- the compositions of the alloys were analyzed by energy dispersive spectroscopy (EDS) (an average of three points), and the evaluation results are presented in Table as the melting point according to the composition of an alloy.
- EDS energy dispersive spectroscopy
- the alloys having the compositions according to the present invention were all found to have melting points that exceed 100 0 C, thus satisfying the European standards relating to the 110°C-grade fusible alloys for PRD.
- the alloys of Comparative Examples all had melting start points of 99.4°C or lower, and were found to be undesirable since melting of the alloys would start at a temperature lower than the minimum reguired temperature (in the case of the 110°C-grade, the allowed temperature range is 110 ⁇ 10°C, and thus, 100 0 C is the minimum required temperature) .
- the fusible alloy In order for a fusible alloy to form strong bonding to the internal walls of a PRD and the interior reinforcement materials, the fusible alloy should have excellent wettability.
- a wettability test is performed by melting alloys of the same weight and measuring the area occupied by the alloy, or by inspecting the cross-section of a specimen that has been melted and quenched, and measuring the wetting angle. A smaller wetting angle means better wettability.
- Fig. l(a) in the upper photograph shows a conventional Bi- Cd-Sn ternary alloy
- Fig. 1 (b) in the lower photograph shows a Pb-Bi-Sn-In quaternary alloy (Example 4) according to the present invention.
- the wetting angle of the Bi-Cd-Sn ternary alloy was measured to be 52.78°, while the wetting angle of the Pb-Bi-Sn-In quaternary alloy of the present invention was measured to 47.25°. Thus, the wetting angle of the alloy of the present invention was confirmed to be smaller.
- a PRD employing a composite material is formed by filling the interior of the PRD body with a fusible alloy mixed with the reinforcement materials as shown in Fig. 2.
- the reinforcement materials used in the present invention were stainless steel spheres having a diameter of about 600 mm (Fig. 2 (a)) and stainless steel cylinders having a length of about 900 mm (Fig. 2 (b) ) , which were used in a mixture.
- the experimental results indicate that when the reinforcement materials were mixed at a ratio of about 50:50, the durability was found to be optimum.
- PRDs were produced using the quaternary fusible alloys according to the present invention, and a durability test was performed. According to the test conditions stipulated by the ISO International Standards, the test temperature was 91°C, the test pressure was 325 bars, and the test duration was 500 hours. After 500 hours of the test, if the fusible alloy inside the PRD did not flow out, the fusible alloy was considered to be acceptable.
- the test procedure is as follows. (1) A sample PRD is placed in a test block, which is in turn placed in an oven.
- the quaternary fusible alloy for PRD of the present invention has a melting point that is appropriate for use according to the 110°C-grade standards, and has excellent wettability as demonstrated by the small wetting angle upon melting.
- PRDs formed of the fusible alloy of the invention can be expected to discharge gases within a short time, and the fusible alloy of the invention is a material which can satisfactorily replace conventional ternary alloys.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- General Engineering & Computer Science (AREA)
- Powder Metallurgy (AREA)
- Manufacture And Refinement Of Metals (AREA)
Abstract
The present invention relates to a fusible alloy for pressure relief devices (PRDs), and the present invention provides a fusible alloy for PRD, the alloy comprising 29.0 to 33.0% by weight of Bi, 14.0 to 21.0% by weight of Sn, 2.0 to 5.0% by weight of In, and substantially Pb for the balance. The fusible alloy for PRD of the invention has a melting point appropriate for use according to the 1100C- grade standards, and has excellent wettability upon melting.
Description
[Description]
[invention Title]
FUSIBLE ALLOY FOR PRESSURE RELIEF DEVICES
[Technical Field]
The present invention relates to a fusible alloy for pressure relief devices (PRDs), and more particularly, to a fusible alloy for PRD, which is appropriate for use according to the 110°C-grade standards and has excellent wettability upon melting.
[Background Art]
Pressure relief devices are safety devices attached to gas cylinder valves in automobiles and the like, which devices play the role of preventing gas explosion by rapidly discharging gases inside the cylinder to the outside when the temperature of the ambient environment rises abnormally to above a specific temperature, such as at the time of fire.
Accordingly, a conceptually ideal PRD is expected to completely cut off the outflow of gases up to a specific temperature, and when the specific temperature is reached, to discharge the entire amount of the gases within a short time. Thus, only those verified products which have
undergone rigorous tests are put into use.
In this light, for example, the European standards stipulate a use of alloys having a melting point acceptable for the 110°C-grade (110±10°C), to provide against safety accidents involving gas explosions.
[Disclosure]
As such fusible alloys for PRD, ternary alloys such as Bi-Pb-Sn alloys, Bi-Cd-Sn alloys and the like have been traditionally used. However, the wettability upon melting of these alloys is not sufficient, and the alloys have had limitations in rapidly discharging gases inside the cylinder to the outside.
Thus, it is an object of the present invention to solve such problems of the prior art, and to provide a new fusible alloy for PRD, comprising a quaternary alloy which ensures excellent wettability upon melting at a specific temperature, and at the same time, meets the requirements stipulated by the European standards as the 110°C-grade.
[Description of Drawings]
Fig. 1 shows photographs showing the wetting angles of the fusible alloy for PRD according to the present invention and of a conventional fusible alloy for PRD, as measured in a wettability test.
Fig. 2 shows scanning electron microscopic (SEM) photographs of exemplary reinforcement materials used in the preparation of the fusible alloy according to the present invention.
[Best Mode]
In order to achieve the above-described object, according to the present invention, there is provided a quaternary fusible alloy for PRD, comprising 29.0 to 33.0% by- weight of bismuth (Bi), 14.0 to 21.0% by weight of tin (Sn), 2.0 to 5.0% by weight of indium (In), and substantially lead (Pb) for the balance.
The present invention chooses to use a quaternary alloy because the low-melting point alloying elements, namely, Pb, Bi, Sn and In, themselves have low melting points, and also because when these elements form a polynary alloy, the alloy may have a eutectic point, thus it being possible to render the melting point of the alloy even lower. For example, in the case of a Pb-Sn alloy, which is a representative solder material, while the melting point of Pb is 3270C, and the melting point of Sn is 232°C, an alloy of Pb with 61.9% of Sn has a melting point of 1830C at the eutectic point. Based on this tendency, the melting point of an alloy can be further lowered by increasing the number of alloying elements to systems of ternary, quaternary and the like.
Meanwhile, according to the present invention, the results of thermodynamic calculations were used as the basis of the primary alloy designs for appropriate composition ratios of the alloying elements. In other words, the melting points of ternary, quaternary and quinary alloys of various compositions were predicted based on the calculations using thermodynamic data. Then, a quaternary system of Bi-Sn-In-Pb that was considered to be an optimum was selected to constitute the alloy of the present invention, and the composition was determined to fall within a specific range through actual experimentation.
Thus, in the present invention, the composition ratios of the alloy-constituting elements were determined to be' 29.0 to 33.0% by weight for Bi, 14.0 to 21.0% by weight for Sn, 2.0 to 5.0% by weight of In, and substantially Pb for the balance. If the respective component elements are contained in the alloy of the invention in amounts beyond the above-described composition ranges, the melting point (in particular, the melting start point) may be lowered to below 100°C, thus causing the alloy to melt at a temperature below the critical temperature; or the melting point may be raised to above 120°C, thus inhibiting efficient discharge of gases at an appropriate temperature and subsequent prevention of safety accident such as gas explosion. Then, such alloys are deprived of the function as the 110°C-grade
fusible alloys for PRD, and are undesirable.
Hereinafter, the present invention will be described in more detail .
Evaluation of main properties of fusible alloy for PRD The properties that are necessary for an alloy to be used as a fusible alloy for PRD, include melting point, wettability, PRD durability, and the like.
Evaluation of melting point
In order to prepare alloys of desired compositions, the composition ratios by weight were calculated, and the elements were respectively weighed. Then, the elements were mixed and melted together to form fusible alloys, and then, mother alloy ingots of the respective compositions, each weighing about 1 kg, were prepared. Subsequently, each fusible alloy was placed on a substrate made of brass and maintained at a desired temperature for 10 minutes using glycerin solution as a heating medium, and then, the presence or absence of melting of the fusible alloy was verified. The compositions of the alloys were analyzed by energy dispersive spectroscopy (EDS) (an average of three points), and the evaluation results are presented in Table as the melting point according to the composition of an alloy.
[Table 1]
As can be seen from Table 1, the alloys having the compositions according to the present invention (Examples 1 to 4) were all found to have melting points that exceed 1000C, thus satisfying the European standards relating to the 110°C-grade fusible alloys for PRD. On the other hand, the alloys of Comparative Examples all had melting start points of 99.4°C or lower, and were found to be undesirable since melting of the alloys would start at a temperature lower than the minimum reguired temperature (in the case of the 110°C-grade, the allowed temperature range is 110±10°C, and thus, 1000C is the minimum required temperature) .
Evaluation of wettability
In order for a fusible alloy to form strong bonding to
the internal walls of a PRD and the interior reinforcement materials, the fusible alloy should have excellent wettability. A wettability test is performed by melting alloys of the same weight and measuring the area occupied by the alloy, or by inspecting the cross-section of a specimen that has been melted and quenched, and measuring the wetting angle. A smaller wetting angle means better wettability. Fig. l(a) in the upper photograph shows a conventional Bi- Cd-Sn ternary alloy, and Fig. 1 (b) in the lower photograph shows a Pb-Bi-Sn-In quaternary alloy (Example 4) according to the present invention.
Referring to Fig. 1, the wetting angle of the Bi-Cd-Sn ternary alloy was measured to be 52.78°, while the wetting angle of the Pb-Bi-Sn-In quaternary alloy of the present invention was measured to 47.25°. Thus, the wetting angle of the alloy of the present invention was confirmed to be smaller.
Evaluation of PRD durability
To evaluate the durability of a PRD, a PRD needs to be actually produced from a fusible alloy. A PRD employing a composite material is formed by filling the interior of the PRD body with a fusible alloy mixed with the reinforcement materials as shown in Fig. 2. The reinforcement materials used in the present invention were stainless steel spheres having a diameter of about 600 mm (Fig. 2 (a)) and stainless
steel cylinders having a length of about 900 mm (Fig. 2 (b) ) , which were used in a mixture. The experimental results indicate that when the reinforcement materials were mixed at a ratio of about 50:50, the durability was found to be optimum.
As such, PRDs were produced using the quaternary fusible alloys according to the present invention, and a durability test was performed. According to the test conditions stipulated by the ISO International Standards, the test temperature was 91°C, the test pressure was 325 bars, and the test duration was 500 hours. After 500 hours of the test, if the fusible alloy inside the PRD did not flow out, the fusible alloy was considered to be acceptable. The test procedure is as follows. (1) A sample PRD is placed in a test block, which is in turn placed in an oven.
(2) A pressure of 325 bars is applied onto the sample PRD by means of air.
(3) The temperature in the oven is adjusted to 910C, and then the sample PRD is maintained therein for 500 hours.
(4) No deformation or operation of the sample PRD is allowed for the duration of 500 hours.
When the test was performed in the above-described manner, those PRDs filled with the fusible alloys of the present invention were all found to be acceptable, and were
confirmed to have durability that is at least equivalent to that of existing alloys.
[industrial Applicability]
As discussed in the above, the quaternary fusible alloy for PRD of the present invention has a melting point that is appropriate for use according to the 110°C-grade standards, and has excellent wettability as demonstrated by the small wetting angle upon melting. Thus, PRDs formed of the fusible alloy of the invention can be expected to discharge gases within a short time, and the fusible alloy of the invention is a material which can satisfactorily replace conventional ternary alloys.
Claims
[CLAIMS]
[Claim l]
A fusible alloy for pressure relief devices, the alloy- comprising 29.0 to 33.0% by weight of bismuth (Bi), 14.0 to 21.0% by weight of tin (Sn), 2.0 to 5.0% by weight of indium (In), and substantially lead (Pb) for the balance.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US12/445,822 US20100303668A1 (en) | 2006-10-26 | 2006-12-28 | Fusible alloy for pressure relief devices |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1020060104429A KR100875440B1 (en) | 2006-10-26 | 2006-10-26 | Soluble alloy for PCR |
| KR10-2006-0104429 | 2006-10-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2008050936A1 true WO2008050936A1 (en) | 2008-05-02 |
Family
ID=39324707
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/KR2006/005825 WO2008050936A1 (en) | 2006-10-26 | 2006-12-28 | Fusible alloy for pressure relief devices |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US20100303668A1 (en) |
| KR (1) | KR100875440B1 (en) |
| WO (1) | WO2008050936A1 (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63266034A (en) * | 1987-04-22 | 1988-11-02 | Sumitomo Electric Ind Ltd | Conductor for fuse |
| JPS63266035A (en) * | 1987-04-23 | 1988-11-02 | Sumitomo Electric Ind Ltd | Conductor for fuse |
| US5248476A (en) * | 1992-04-30 | 1993-09-28 | The Indium Corporation Of America | Fusible alloy containing bismuth, indium, lead, tin and gallium |
| JP2003013165A (en) * | 2001-06-28 | 2003-01-15 | Sorudaa Kooto Kk | Fusible alloy and wire rod for thermal fuse, and thermal fuse |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS589136B2 (en) * | 1975-03-20 | 1983-02-19 | 株式会社東芝 | BI-SN-IN-PB Keigokin |
-
2006
- 2006-10-26 KR KR1020060104429A patent/KR100875440B1/en active IP Right Grant
- 2006-12-28 US US12/445,822 patent/US20100303668A1/en not_active Abandoned
- 2006-12-28 WO PCT/KR2006/005825 patent/WO2008050936A1/en active Application Filing
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63266034A (en) * | 1987-04-22 | 1988-11-02 | Sumitomo Electric Ind Ltd | Conductor for fuse |
| JPS63266035A (en) * | 1987-04-23 | 1988-11-02 | Sumitomo Electric Ind Ltd | Conductor for fuse |
| US5248476A (en) * | 1992-04-30 | 1993-09-28 | The Indium Corporation Of America | Fusible alloy containing bismuth, indium, lead, tin and gallium |
| JP2003013165A (en) * | 2001-06-28 | 2003-01-15 | Sorudaa Kooto Kk | Fusible alloy and wire rod for thermal fuse, and thermal fuse |
Also Published As
| Publication number | Publication date |
|---|---|
| US20100303668A1 (en) | 2010-12-02 |
| KR20080037381A (en) | 2008-04-30 |
| KR100875440B1 (en) | 2008-12-22 |
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