CA2954570A1 - Encased temperature and crack resistant magnetic stirring bar - Google Patents
Encased temperature and crack resistant magnetic stirring bar Download PDFInfo
- Publication number
- CA2954570A1 CA2954570A1 CA2954570A CA2954570A CA2954570A1 CA 2954570 A1 CA2954570 A1 CA 2954570A1 CA 2954570 A CA2954570 A CA 2954570A CA 2954570 A CA2954570 A CA 2954570A CA 2954570 A1 CA2954570 A1 CA 2954570A1
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- CA
- Canada
- Prior art keywords
- magnetic
- stirring bar
- high temperature
- threading
- rod
- 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
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F33/00—Other mixers; Mixing plants; Combinations of mixers
- B01F33/45—Magnetic mixers; Mixers with magnetically driven stirrers
- B01F33/452—Magnetic mixers; Mixers with magnetically driven stirrers using independent floating stirring elements
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Hard Magnetic Materials (AREA)
Abstract
The present invention relates in general to a magnetic stirring system wherein a liquid or mixture of liquid and solid powder is stirred by means of a magnetic stirring bar placed therein and driven by a rotating magnetic field underneath the container. The stir bar is tightly encased by durable materials that are temperature resistant and shatter proof. The covering materials are also chemically inert and do not contaminate or react with the reaction mixture contained therein.
Description
ENCASED TEMPERATURE AND CRACK RESISTANT MAGNETIC STIRRING BAR
BACKGROUND OF THE INVENTION
In chemistry and biology laboratories, magnetic stirrers are often used for mixing modest amounts of liquids or mixtures of liquids and solid powders. A magnetic stirrer employs a rotating magnetic field placed beneath the vessel with the liquids or mixtures of liquids and solid powders to cause a stirring bar, which is immersed in the liquid or the mixture of liquids and solid powders, to spin very quickly, thus stirring the liquids or mixtures.
The rotating magnetic field may be created either by a rotating permanent magnet or assembly of electromagnets.
Magnetic stirrers can be used for both open and hermetically closed vessels.
Specially, when it is used in hermetically closed vessels, it is not necessary to use the costly and complicated rotary seals. More specially, this also avoids using lubricants which could contaminate the reaction vessel and the product. A magnetic stirring bar is a magnet that is encased in materials that won't react with the fluid it is immersed in. U.S. Patent No. 2,844,363 disclosed a coated magnet in plastic or covering it with glass to make it chemically inert and not contaminate or react with the reaction mixture they are in.
Nowadays, many kinds of shaped magnetic stirring bars are invented for better mixing effects. No matter what shape is used, the most used magnetic stirring bars are typically coated in Teflon, or less often, in glass, as glass or Teflon does not appreciably affect a magnetic field and the chemical reactions. These coated stirring bars are commonly used in glass vessels at a relatively low temperature and at atmospheric pressure or even in vacuums.
The highest used temperature for Teflon coated stirring bars is 270 C. Teflon coated magnetic stir bars used in most low temperature chemical testing can be softened and even molten at high temperatures and finally fall off from the magnetic rod.
Instead of a Teflon coated one, a glass encased stirring bar can be used at higher temperatures.
Although an encasing of glass can be used at high temperatures, the encased glass can easily break during the stirring, especially, when it is stirred vigorously.
The stirring bar may jump and collide with the rigid walls of the reactor. This can break the encasing glass. Chemical reactions do not only occur at low temperatures and low pressure, as many reactions occur at high temperatures and at high pressure. As a result, stainless steel autoclaves which are equipped with complicated rotary seals are frequently used for such conditions. This makes the autoclave more expensive. If the use of a complicated rotary seal can be avoided, the cost of the autoclave may greatly be reduced. A high pressure reactor and a magnetic stirrer equipped with a stirring bar which is covered by materials that are temperature resistant and shatter proof is thus desirable and can replace the more expensive autoclave.
It is therefore the object of the present invention to provide a method for preparing a magnetic stir bar encased or covered with materials which are temperature resistant and are less fragile so as to be used in high temperature conditions. The coverings are chemically inert and do not contaminate or react with the reaction mixture contained therein.
It is a further object of the present invention to provide a cost-effective autoclave for high temperature and high pressure condition applications.
BRIEF SUMMARY OF THE INVENTION
According to the present invention, methods are provided for preparing a stirring bar covered with materials that are shatter proof and afford better temperature resistance.
The covering material is chemically inert, has no appreciable effect on the magnetic field, such as stainless steel, ceramic or other materials which could be used at high temperatures in order to offer fragility resistance. The use of the present invention in a high pressure and high temperature reactor can replace a complicated magnetic rotary equipped autoclave system.
DETAILS OF THE DESCRIPTION OF THE INVENTION
The present invention relates to the preparing of a magnetic stirring bar covered with materials which are temperature resistant and shatter proof so as to be used in a rigid autoclave reactor at high temperatures in a vigorously stirring environment.
The invention relates to methods of manufacturing the magnetic stirring bars without significantly reducing their magnetic flux.
This invention relates to the use of a cost-effective autoclave for high temperature and high pressure reactions. Namely, this invention replaces the autoclave equipped with a complicated magnetic rotary system with a magnetic stirrer as described in the present invention. The key issue of this invention is to have a temperature resistant and fragility resistant stirring bar.
Magnetic stirring bars are coated magnets used to stir liquids or mixtures of liquids and solid powders in a sealed container. The covering materials of the magnetic stirring bar include materials with temperature and crack resistance properties and are chemically inert when it is immersed in the fluid and/or mixture. The covering materials include, but are not limited to, stainless steel, ceramic, composite materials, other metals, should have no or less appreciable effect on magnetic fields and the chemical reactions.
The methods to cover the magnetic bars are: machining, welding, threading, and electroless plating, or a combination of these methods.
DESCRIPTION OF THE DRAWINGS
Fig. 1-5 is an axial cross-sectional view of the stirring bar at each construction stage.
Referring to the drawings in detail, in all figures, item 1 is the magnetic metallic bar which may be of any known or other suitable permanent magnet material. As the material used to construct magnetic metallic bars are usually rather vulnerable to many reagents, the magnetic rod in the present invention is wholly enclosed in a uniform thickness tube 2 of a stainless steel or other material which is highly resistant to most reagents and resistant to high temperatures. 2 has no or less appreciable effect on magnetic fields. 5 are internal threads at the ends of tube 2 with a distance of 8-10 threads and 6 is the plug with external threads with a distance of 10-12 threads. 7 is an 0-ring sealing gasket, such as graphite, which can withstand high temperatures.
According to the present invention, in Fig. 1, the uniform thickness of the stainless steel tube 2 is firstly sealed at one end 3 and the surface of this end is machined into a shaped arc. The tube 2 also can be manufactured from boaring a metallic rod so that one end of the tube is not boared through, therefore maintains one closed end.
According to the present invention the magnetic bar 1 is fitted into the one end sealed stainless steel tube 2, the external diameter of the magnetic rod and the inner diameter of the tube 2 is so dimensioned that the rod will fit in the tube with sufficient tightness. The tube 2 is of sufficient length for bar 1. The other end 4 is then sealed by welding and it is then machined to the desired shape of an arc. The shape at both ends is the same in the arc and the finished magnetic stirring bar is in symmetry.
A point of consideration and concern is that the high temperature of welding may cause the loss of the original magnetic flux of the rod. With the present invention, the finished stirring bars were then tested for petroleum vacuum residue upgrading in an autoclave operating at high temperatures and high pressure and no obvious loss of their magnetic flux was found.
In order to completely avoid the concern of loss of original magnetic flux of the rod by welding, a design using threads instead of welding is proposed and shown in Fig.2. The prior stage is the same as described therebefore. Only the second end manufacturing process is modified. The second end or threaded openings 5 of the tube 2 is closed by externally threaded plug 6 of the same stainless steel material. The second end of the tube is internally threaded with the threads 5 having 8-10 threads. A male plug 6 with external threads having 10-12 threads is used for closing the second end. If necessary, an 0-ring gasket 7 is used for ensuring the sealing. The plug 6 is thus threaded into the internal threads 5 and presses the 0-ring with sufficient force to the end of rod 1. To facilitate assembly of the plug, a hexagonal kerf 8 is provided in plug 6 to receive a hexagonal L key, and two flat kerfs 9 are provided on tube 2 to receive a wrench. After tightening the plug 6 as shown in Fig. 3, the second end is machined to the same shape as end 3 and makes both ends in symmetry. The shape of the finished stirring bar is then the same as Fig. 1.
Another design is that both tubular ends for the stirring bar can be designed using threads and plugs as shown in Fig. 4. The stirring bar can be used as is after tightening as shown in Fig. 5 or be machined to the shape as shown in Fig. 1.
Using electroless plating technology to coat the magnetic rod with composite materials, such as NiP, is proposed. As NiP has high temperature and fiction resistance, it can be used in a high temperature autoclave. Using a graphene coating technology can also achieve the desired effect of the present invention.
BACKGROUND OF THE INVENTION
In chemistry and biology laboratories, magnetic stirrers are often used for mixing modest amounts of liquids or mixtures of liquids and solid powders. A magnetic stirrer employs a rotating magnetic field placed beneath the vessel with the liquids or mixtures of liquids and solid powders to cause a stirring bar, which is immersed in the liquid or the mixture of liquids and solid powders, to spin very quickly, thus stirring the liquids or mixtures.
The rotating magnetic field may be created either by a rotating permanent magnet or assembly of electromagnets.
Magnetic stirrers can be used for both open and hermetically closed vessels.
Specially, when it is used in hermetically closed vessels, it is not necessary to use the costly and complicated rotary seals. More specially, this also avoids using lubricants which could contaminate the reaction vessel and the product. A magnetic stirring bar is a magnet that is encased in materials that won't react with the fluid it is immersed in. U.S. Patent No. 2,844,363 disclosed a coated magnet in plastic or covering it with glass to make it chemically inert and not contaminate or react with the reaction mixture they are in.
Nowadays, many kinds of shaped magnetic stirring bars are invented for better mixing effects. No matter what shape is used, the most used magnetic stirring bars are typically coated in Teflon, or less often, in glass, as glass or Teflon does not appreciably affect a magnetic field and the chemical reactions. These coated stirring bars are commonly used in glass vessels at a relatively low temperature and at atmospheric pressure or even in vacuums.
The highest used temperature for Teflon coated stirring bars is 270 C. Teflon coated magnetic stir bars used in most low temperature chemical testing can be softened and even molten at high temperatures and finally fall off from the magnetic rod.
Instead of a Teflon coated one, a glass encased stirring bar can be used at higher temperatures.
Although an encasing of glass can be used at high temperatures, the encased glass can easily break during the stirring, especially, when it is stirred vigorously.
The stirring bar may jump and collide with the rigid walls of the reactor. This can break the encasing glass. Chemical reactions do not only occur at low temperatures and low pressure, as many reactions occur at high temperatures and at high pressure. As a result, stainless steel autoclaves which are equipped with complicated rotary seals are frequently used for such conditions. This makes the autoclave more expensive. If the use of a complicated rotary seal can be avoided, the cost of the autoclave may greatly be reduced. A high pressure reactor and a magnetic stirrer equipped with a stirring bar which is covered by materials that are temperature resistant and shatter proof is thus desirable and can replace the more expensive autoclave.
It is therefore the object of the present invention to provide a method for preparing a magnetic stir bar encased or covered with materials which are temperature resistant and are less fragile so as to be used in high temperature conditions. The coverings are chemically inert and do not contaminate or react with the reaction mixture contained therein.
It is a further object of the present invention to provide a cost-effective autoclave for high temperature and high pressure condition applications.
BRIEF SUMMARY OF THE INVENTION
According to the present invention, methods are provided for preparing a stirring bar covered with materials that are shatter proof and afford better temperature resistance.
The covering material is chemically inert, has no appreciable effect on the magnetic field, such as stainless steel, ceramic or other materials which could be used at high temperatures in order to offer fragility resistance. The use of the present invention in a high pressure and high temperature reactor can replace a complicated magnetic rotary equipped autoclave system.
DETAILS OF THE DESCRIPTION OF THE INVENTION
The present invention relates to the preparing of a magnetic stirring bar covered with materials which are temperature resistant and shatter proof so as to be used in a rigid autoclave reactor at high temperatures in a vigorously stirring environment.
The invention relates to methods of manufacturing the magnetic stirring bars without significantly reducing their magnetic flux.
This invention relates to the use of a cost-effective autoclave for high temperature and high pressure reactions. Namely, this invention replaces the autoclave equipped with a complicated magnetic rotary system with a magnetic stirrer as described in the present invention. The key issue of this invention is to have a temperature resistant and fragility resistant stirring bar.
Magnetic stirring bars are coated magnets used to stir liquids or mixtures of liquids and solid powders in a sealed container. The covering materials of the magnetic stirring bar include materials with temperature and crack resistance properties and are chemically inert when it is immersed in the fluid and/or mixture. The covering materials include, but are not limited to, stainless steel, ceramic, composite materials, other metals, should have no or less appreciable effect on magnetic fields and the chemical reactions.
The methods to cover the magnetic bars are: machining, welding, threading, and electroless plating, or a combination of these methods.
DESCRIPTION OF THE DRAWINGS
Fig. 1-5 is an axial cross-sectional view of the stirring bar at each construction stage.
Referring to the drawings in detail, in all figures, item 1 is the magnetic metallic bar which may be of any known or other suitable permanent magnet material. As the material used to construct magnetic metallic bars are usually rather vulnerable to many reagents, the magnetic rod in the present invention is wholly enclosed in a uniform thickness tube 2 of a stainless steel or other material which is highly resistant to most reagents and resistant to high temperatures. 2 has no or less appreciable effect on magnetic fields. 5 are internal threads at the ends of tube 2 with a distance of 8-10 threads and 6 is the plug with external threads with a distance of 10-12 threads. 7 is an 0-ring sealing gasket, such as graphite, which can withstand high temperatures.
According to the present invention, in Fig. 1, the uniform thickness of the stainless steel tube 2 is firstly sealed at one end 3 and the surface of this end is machined into a shaped arc. The tube 2 also can be manufactured from boaring a metallic rod so that one end of the tube is not boared through, therefore maintains one closed end.
According to the present invention the magnetic bar 1 is fitted into the one end sealed stainless steel tube 2, the external diameter of the magnetic rod and the inner diameter of the tube 2 is so dimensioned that the rod will fit in the tube with sufficient tightness. The tube 2 is of sufficient length for bar 1. The other end 4 is then sealed by welding and it is then machined to the desired shape of an arc. The shape at both ends is the same in the arc and the finished magnetic stirring bar is in symmetry.
A point of consideration and concern is that the high temperature of welding may cause the loss of the original magnetic flux of the rod. With the present invention, the finished stirring bars were then tested for petroleum vacuum residue upgrading in an autoclave operating at high temperatures and high pressure and no obvious loss of their magnetic flux was found.
In order to completely avoid the concern of loss of original magnetic flux of the rod by welding, a design using threads instead of welding is proposed and shown in Fig.2. The prior stage is the same as described therebefore. Only the second end manufacturing process is modified. The second end or threaded openings 5 of the tube 2 is closed by externally threaded plug 6 of the same stainless steel material. The second end of the tube is internally threaded with the threads 5 having 8-10 threads. A male plug 6 with external threads having 10-12 threads is used for closing the second end. If necessary, an 0-ring gasket 7 is used for ensuring the sealing. The plug 6 is thus threaded into the internal threads 5 and presses the 0-ring with sufficient force to the end of rod 1. To facilitate assembly of the plug, a hexagonal kerf 8 is provided in plug 6 to receive a hexagonal L key, and two flat kerfs 9 are provided on tube 2 to receive a wrench. After tightening the plug 6 as shown in Fig. 3, the second end is machined to the same shape as end 3 and makes both ends in symmetry. The shape of the finished stirring bar is then the same as Fig. 1.
Another design is that both tubular ends for the stirring bar can be designed using threads and plugs as shown in Fig. 4. The stirring bar can be used as is after tightening as shown in Fig. 5 or be machined to the shape as shown in Fig. 1.
Using electroless plating technology to coat the magnetic rod with composite materials, such as NiP, is proposed. As NiP has high temperature and fiction resistance, it can be used in a high temperature autoclave. Using a graphene coating technology can also achieve the desired effect of the present invention.
Claims (8)
1. A magnetic stirring bar, comprising a magnetic metallic rod element that is encased in a tightly fitted continuous and homogeneous casing that can sustain high temperatures and is shatter proof while it is chemically inert to the operating environment . The covering materials include, but are not limited to, stainless steel, composite materials, and other chemically inert metals.
2. The method comprises a cylindrical chamber closed by sealing the open end by using welding, threading, threading with an O-ring gasket.
3. The method of coating the magnetic rod by electroless plating with composite materials such as NiP.
4. The coating of the magnetic rod by graphene.
5. The method as in claim 2, wherein the sealing by threading or threading with an O-ring gasket avoids high temperature welding.
6. An autoclave using such a high temperature resistance and shatter proof stirring bar for high temperature and high pressure reaction instead of using an expensive autoclave with a complicated magnetic rotary system for impeller.
7. The high temperature is a temperature that is greater than 400°C
where Teflon coated stirring bars cannot be used.
where Teflon coated stirring bars cannot be used.
8. The high temperature resistant and shatter proof stirring bar can be of any shape including, but not limited to a rod, cross structure, plate etc.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA2954570A CA2954570A1 (en) | 2017-01-13 | 2017-01-13 | Encased temperature and crack resistant magnetic stirring bar |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA2954570A CA2954570A1 (en) | 2017-01-13 | 2017-01-13 | Encased temperature and crack resistant magnetic stirring bar |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2954570A1 true CA2954570A1 (en) | 2018-07-13 |
Family
ID=62838139
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2954570A Abandoned CA2954570A1 (en) | 2017-01-13 | 2017-01-13 | Encased temperature and crack resistant magnetic stirring bar |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2954570A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109003800A (en) * | 2018-07-20 | 2018-12-14 | 陈亮 | Production process for coating graphene on surface of magnet |
-
2017
- 2017-01-13 CA CA2954570A patent/CA2954570A1/en not_active Abandoned
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109003800A (en) * | 2018-07-20 | 2018-12-14 | 陈亮 | Production process for coating graphene on surface of magnet |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |
Effective date: 20190819 |