FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
The Patent Rules, 2003
Complete Specification
(See section 10 and rule 13)
Improved Magnetic Seal Assembly
Omega-Kemix Private Ltd.
R-333 TTC, MIDC Rabale, Navi Mumbai, 400 701, Maharashtra State, India
An Indian company registered under the Companies Act, 1956
The following specification describes the invention:
Improved Magnetic Seal Assembly
This specification discloses an improvement over the invention for which a patent (no. 211631, granted on 05 November, 2007) had been granted by the Indian Patent Office on.
FIELD OF INVENTION
The field of the invention generally relates to magnetic sealing devices used for transfer of torque involving rotating parts. The invention particularly relates to use of magnetic seals used in industrial mixers.
DESCRIPTION OF PRIOR ART
Reference is made to the Indian patent no. 211631 granted on 05 Novenber.
2007. The invention disclosed therein is incorporated herein by reference..
The Indian patent 211631 disclosed a magnetic seal assembly (MSA) comprising a sealed chamber having a rotating shaft/impeller inside. It incorporates an inner magnetic assembly which is attached to the rotating shaft. Outside the sealed chamber, an outer magnet assembly is rotated by means of a prime mover (D). Magnetic flux is transmitted from the outer magnet assembly to the inner magnet assembly through walls of the chamber, thus transmitting contact-free torque, which rotates the inner shaft/impeller. The MSA is also fitted with devices to align the inner/outer magnets and shaft,

hold these in position during rest position or while rotating. It is also fitted with sealing devices to prevent solids or dust from depositing on inner magnet surfaces inside the shroud or to prevent contents of the sealed chamber to escape to the external environment.
The MSA disclosed in the patent no. 211631 represented a significant advance over the then current technologies used for sealing of industrial mixtures. It was aimed at a magnetic seal assembly that:
a) Leaves little or no wear and tear on shaft.
b) Saves power through minimizing friction between moving parts.
c) Eliminates necessity of using sealing fluids that could potentially leak, into the reactor in case of the failure of the seal-face.
d) Provides a non-contact method of sealing, resulting in long life and trouble-free operation.
e) Ensures safe sealing of vessel fluids at high pressures and temperatures.
f) Ensures safe sealing in case of applications requiring use of corrosive gases such as Chlorine. Bromine etc.
g) Ensures safe sealing of hazardous, toxic or flammable fluids.
h) Provides a shaft that suspends inside the agitator by a cantilever
arrangement.
i) Can be used on industrial scale where mixing volumes are large which
require large torque and where the shaft diameters can be suitably high.

However, further improvements have been made to the MSA disclosed in the Indian patent no. 211631.
In the patent 211631, an anti-dust bush (40) was provided which acted as a dust filter between the vessel (B) and shroud (2)/inner bearing housing (4). It also acted as a seal, so that pressure equalization between the vessel and shroud (2) or inner bearing housing (4) areas would be through the Central Hole (46).
A major area of concern remains in design and selection of the anti-dust bush (40). This needed to be porous for it to act as a filter, and resilient, to act as a seal between the Inner Shaft (34) and inner bearing housing (4). It also needs to be fully back-flushable. so that during vessel depressurization, solids filtered in the anti-dust bush (40) would fall back into the vessel, and not stay embedded in the anti-dust bush (40).
It has been noted by the applicant that over a period of a few years, some solid dust would pass through the anti-dust bush (40) and enter the inner bearings (35 & 36). Also, process vapors permeate through the anti-dust bush (40), and condense inside the bearing housing (4). This solid dust and condensed vapor builds up over a period of time. At times, the condensed vapors may crystallize and form hard crystals, which remain entrapped in the inner bearings (35 & 36).

Furthermore, solid dust and process vapors may have also entered into the bearing housing (4) and inner bearings (35 & 36) through the central hole (46). This leads to rapid and irreversible failure of the inner bearings (35 & 36).
In addition, it is not possible to remove the permeated solid dust or condensed vapors without dismantling the entire assembly. The cleansing of the apparatus is thus a cumbersome and tedious operation, if at all possible. This therefore is a matter of concern during product changeover, for example, particularly in pharmaceutical manufacture, where the previous product could contaminate the new product.
There is therefore a need for improving the magnetic seal assembly of the Indian Patent no. 211631 which will that successfully addresses the above-mentioned issues, and gives a safe, trouble-free, robust and leak-proof contact-less seal for agitator drives and similar equipment for industrial scale applications.
OBJECTS OF THE INVENTION
Accordingly an object of the present an improved magnetic seal assembly is to provide a magnetic seal assembly that would prevent solid dust from passing into the inner bearings (35 & 36).
Another object of the improved magnetic seal assembly of the present invention is to provide an improved magnetic seal assembly is to provide a magnetic seal

assembly that provides a porous and resilient seal between the Inner Shaft (34) and inner bearing housing(4).
A further objective of the improved magnetic seal assembly of the present invention is to prevent escape of vapors into the inner bearings where they may get crystallized and remain trapped.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 schematically shows the magnetic seal assembly of the invention in cross
section.
Figure 2 shows shroud with cover flange and O-ring.
Figure 3 shows outer magnet assembly.
Figure 4 shows the driver coupling with outer upper bearing.
Figure 5 shows stool assembly along with motor, stool bearings, outer magnet
assembly, a leak detection port, and mounting flange with Orings.
Figure 6 shows inner magnet assembly.
Figure 7 shows inner shaft with inner washer with lock bolt, inner bearings, inner
lock nut and lock washer, along with driven shaft.
Figure 8 shows bearing assembly with inner bearings, anti-dust bush, and vessel
with nozzle flange and gasket.

LIST OF REFERENCE NUMERALS
Vessel Nozzle flange (A) Stool jacket (29)
Vessel or reactor (B) Inner magnet holder (30)
Gasket (C) Inner magnets (31)
Prime mover (D) Inner sleeve (32)
Mounting flange (1) Inner core (33)
Static shroud (2) Inner shaft with coupling (34)
Lower stool flange (LSF) (3) Upper inner bearing (35)
Bearing housing (4) Lower inner bearing (36)
Bearing lock (5) Inner lock nut (37)
Bolts for bearing lock (6) Inner lock washer (38)
Driver coupling bolts (8) Lower Anti-Dust bush (40)
Jacket Inlet connection (10a) Outer O-ring (41)
Jacket Outlet connection (1 Ob) Oil reservoir (42)
Angled holes (11) Inner washer (43)
Shroud shell (12) Inner shaft lock bolt (44)
Shroud flange (13) Driven Shaft (45)
Shroud cap (14) Central Hole (46)
Shroud bolts (15) Upper Anti-Dust Bush (47)
Inner O-ring (} 6) Leak Detection Port (48)
Outer magnet holder (17) Oil Drain Valve (49)
Outer magnets (18) Oil Overflow Valve (50)
Outer lock nut (23) Upper outer washer (UOW) (20)
Outer lock washer (24) Driver coupling (21)
Lower outer bearing (26) Upper outer bearing (22)
Stool shell (27) Lower outer washer (LOW) (19)
Upper stool flange (USF) (28)

SUMMARY OF ORIGINAL AND IMPROVED INVENTIONS The magnetic seal assembly (MSA) was disclosed in the Indian Patent 211631 comprising a sealed chamber having a rotating shaft/impeller inside. An inner magnetic assembly was attached to the rotating shaft. Outside the sealed chamber, an outer magnet assembly was rotated by means of a prime mover (D). Magnetic flux was transmitted from the outer magnet assembly to the inner magnet assembly through walls of the chamber, thus transmitting contact-free torque, which rotates the inner shaft/impeller. The MSA was also fitted with devices to align the inner/outer magnets and shaft, hold these in position during rest position or while rotating. It was also fitted with sealing devices to prevent solids or dust from depositing on inner magnet surfaces inside the shroud or to prevent contents of the sealed chamber to escape to the external environment.
The improvement comprises replacing the lower anti-dust bush with a seal (51) which could be a single or multiple lip seal, a self-energising seal, a mechanical seal, or any other suitable sealing device between a stationary and rotating part (in the present instance, between the Inner Bearing Housing (4) and Inner Shaft (34). It also comprises providing a pressure equalizer (52) connects the vessel headspace to the Central Hole (46). A further improvement is made in the form of an improved design of The Inner Lower Bearing (36) so as to permit axial movement of the Inner shaft (34), thereby eliminating axial stresses in the Inner Lower Bearing (36). As yet another improvement, a sleeve (54), like a hollow cylinder, is provided which serves as a distance piece between inner

races of the two inner Bearings (35 & 36) thereby restricting the axial movement of the inner race of the inner lower bearing (36) as required. As a still further improvement, The Bearing Housing (4) is made hollow, wherethrough a coolant such as oil, water, brine, or cold air, etc is circulated. This helps keep the Inner Bearings (35 & 36) cool, and ensures longer operating life. This arrangement also helps cool the Seal (51).
DETAILED DESCRIPTION OF THE INVENTION
The description of the granted Indian patent 211631 is incorporated here by reference.
The attached Figure 1A shows the improved MSA. Figure 1 of the granted Indian patent 211631 becomes redundant for the purpose of the improved MSA.
As one of the improvements, a Seal (51) replaces the anti-dust bush (40). Further, a Dust Filter (53) is mounted on the Inner Shaft (34). The Seal (51) could be a lip seal, a self-energising seal, a mechanical seal, or any other suitable sealing device between a stationary and rotating part, namely, between the Inner Bearing Housing (4) and Inner Shaft (34). The seal does not act as a filter.
As another improvement, a Pressure Equalization Port (52) is provided at the lower end of the inner shaft with coupling (34). The pressure equalization port connects the vessel headspace to the Central Hole (46). The Dust Filter (53) is

located at the junction of the Pressure Equalization Port and the Central Hole (46). Since the Dust Filter is located in the Inner Shaft (34), it rotates along with the Inner Shaft; therefore there is no relative motion between the Inner Shaft (34) and the Dust Filter (53). Optionally, the pressure equalisation port may be mounted eccentrically on the inner shaft coupling.
As vessel pressure increases, vessel fluids pass through the Dust Filter (53) into the Shroud (2) and Inner Bearing Housing (4). This results in pressure equalization between the Vessel (B) and Shroud/Inner Bearing Housing (2/4). The Dust Filter (53) effectively prevents solids from entering the Shroud (2) or Inner Bearing Housing (4). As a result, the Shroud and Inner Bearing Housing remain dust-free. This also means that the Inner Bearings (35 &36) are dust-free.
The Dust Filter (53) can be fitted to the Inner Shaft coupling (34) in various ways. It can be bolted or screwed (or attached in any other suitable way) to the Inner Shaft coupling (34). It can also be sandwiched between Inner Shaft couplings (34), or can even project into the Lower Inner Shaft (45), if it is hollow. Actual fitment of the Dust Filter (53) on the Inner Shaft (34) is a matter of mechanical detail, as long as filtration is complete and effective. For example, the Dust Filter (53) could be fitted on the Inner Bearing Housing (4), with a Pressure Equalisation Port (52)
A Sleeve (54), like a hollow cylinder, serves as a distance piece between inner races of the two Inner Bearings (35) and (36).

As the Dust Fiiter (53) prevents ingress of solid particles into the Shroud (4), or into Inner Bearings (35 & 36), the Upper Anti-Dust Bush (47) provided in the MSA has become redundant, and is hence deleted.
Optionally, the Inner Bearing Housing (4) are provided with an annular space and are thus hollow, and provided with coolant inlet/outlet ports (55 & 56). This helps the inner bearings (35 & 36) as well as the Seal (51) to run without overheating, which can enhance the operating life of these components.
Separation of the Sealing and filtration (dust prevention) elements as described above ensures more effective sealing as well as more reliable filtration. As a further consequence of this modification, the inner bearings (35 & 36) are optionally lubricated, provided that vessel fluids entering the inner bearing housing (46), via the dust filter (53), are immiscible with bearing lubricants. Lubricated bearings will withstand higher loads, and have a longer life. This modification also permits a wider choice in selection of bearing materials.
It will be apparent from the above description that the present invention has the following key advantages over the MSA disclosed in Indian patent number 211631:
1. As the sealing and filtration (dust prevention) functions are carried out through separate elements, the improved MSA ensures a more effective sealing as well as more reliable filtration than the original MSA.

2. The pressure equalization between the shroud and the vessel is more effective.
3. The axial stresses in the inner lower bearing (36) are eliminated as the axial movement of the inner race of the inner lower bearing (36) is limited as required.
4. The inner bearings (35 and 36) are cooled more effectively than in the original MSA.
In view of the detailed foregoing description of the present invention, it will be apparent to a person skilled in the art that the improved MSA basically comprises the following items:
1. An improved magnetic seal assembly as disclosed in Indian patent 211631 wherein the improvement comprises:
(a) seal (51) which replaces the anti-dust bush (40),
(b) a dust filter (53),
(c) a sleeve,
(d) an annular space provided in the inner bearing housing,
wherein, said seal and said dust filter are mounted on the Inner Shaft (34); said sleeve is provided around the inner shaft between the inner bearings (35 and 36); said annular space is optionally filled with a coolant.

2. An improved magnetic seal assembly as described in item 1 wherein said seal is selected from a group comprising a Jip sea], a seJf-energising seal, a mechanical seai, or any other suitable sealing device between a stationary and rotating part.
3. An improved magnetic seal assembly as described in items 1 and 2, wherein the inner bearings (35 & 36) are lubricated, provided that vessel fluids entering the inner bearing housing (46), via the dust filter (53). are immiscible with bearing lubricants.
While the above description contains many specificities, these should not be construed as limitation in the scope of the invention, but rather as an exemplification of the preferred embodiments thereof. Many other variations are possible. Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their legal e