The present disclosure relates to an arrangement of a hose liner and hose fitting which can reduce the potential for contamination between the hose liner and the hose fitting. More particularly, one aspect is related to an arrangement of an interface between a fluoropolymer lined hose and a sealing flange of a hose fitting which reduces the potential for entry of contamination therebetween.
Within industries concerned with conveying chemical and pharmaceutical media under conditions of very high purity hose and piping end fitting connections are commonly arranged in accordance with the American Society of Mechanical Engineers Bio-Pharmaceutical Equipment (ASME BPE 2009) standard, which is incorporated by reference herein in its entirety. These fitting designs are generally robust and trouble-free for users. For example, one commonly used type of hose fitting is a “sanitary flange fitting” 101 shown in the section view in
Sanitary fittings configured in accordance with ASME BPE 2009 also include a concave annular groove 107 formed in the face 105, which facilitates alignment of a sanitary sealing gasket having a mating convex annular surface. Such a gasket is disposed between two mating sanitary fittings 101 and held in position by the application of compressive forces from the sanitary fittings using a clamp, as is known in the art.
In response to the problem of contamination accumulation between the inner end 103 and the liner 104, hoses with flared-through liner were developed, an example of which is shown in
While flare-through hose liner 204 and fitting 201 designs are considered a solution to the foregoing problem of entrapment of contamination in conventional sanitary hose assemblies, contamination problems remain with flare-through designs. Specifically, the sealing surface 208 tends to warp in a wavy pattern, allowing contaminants to be introduced between gaps formed between an inner side of the sealing surface 208 and the flanged face 205 of the fitting 201. Although this area is not part of the normal fluid stream, it is known to be resistant to normal cleaning methods, and subsequent bacterial migration or leaching can contaminate the fluid stream. The existing flare-through designs (e.g.,
However, both of these conventional solutions have drawbacks. First, designs which rely on the moldability and stability of the plastic liner to achieve a flat flare surface still suffer from the problem of contaminants entering behind the flare 208 due to wicking. The flare-through hose can suffer from wicking (i.e., capillary) action of liquid that causes the liquid to migrate into and remain in any small clearances between the flared liner 208 and the face 205 of the fitting 201.
Moreover, designs which rely on adhesive(s) to bond the flared sealing surface 208 to the face 205 are also problematic. The commonly used liner 204 materials are a class of plastics known as fluoroplastics. The very qualities which make these materials desirable for high purity applications, including chemical resistance and low affinity for liquid media, make them very difficult to bond with traditional adhesives. Accordingly, the surface of these plastics must be etched or otherwise treated by one of several techniques to form a surface which can be bonded with adhesives. A problem with etching or treating the liner is that neither the etched surface, nor the adhesive are safe for environments requiring high purity. Firstly, the adhesives are toxic chemicals. Secondly, the etching or treatment process works by stripping sub-atomic particles and otherwise modifying the plastic on a molecular level, effectively creating a surface of unknown chemical make-up. As the etching and adhesive are not in the fluid stream, the design can be functional, but the presence of these materials adds a level of risk to the hose design. In the event of a breach of the liner 204, a potentially highly toxic substance can be introduced to the process media.
Accordingly, solutions are set forth below for the problems associated with flared through hoses discussed above.
In a first aspect a method of making a hose is provided that includes providing a fitting configured to receive a hose liner therethrough and configured to receive a material configured to be bonded to the hose liner. The method includes receiving the material in the fitting, drawing the hose liner through the fitting, and bonding the material to the hose liner such that the hose liner and material are secured to an outer face of the fitting.
In another aspect, a hose is provided that includes a hose liner, a retaining member extending from the hose liner, at least one fitting having an outer sealing face. The fitting is configured to receive the hose liner therethrough and is also configured to engage at least a portion of the retaining member to retain at least a portion of the hose liner against the sealing face of the fitting.
In yet another aspect, a fitting for a hose is provided. The fitting includes a body portion configured to received a hose liner therethrough, and a flanged portion extending from the body portion including an outwardly directed sealing flange. The flanged portion is configured to receive a hose liner therethrough. The sealing flange is configured to receive a portion of the hose liner and is configured to receive and retain at least a portion of a retaining member when the retaining member is in a melt-processable state and when the retaining member is in a bonded state when bonded to the portion of the hose liner.
Also, in another aspect a hose produced according to a method is provided. The method includes providing a fitting configured to receive a hose liner therethrough and configured to receive a material configured to be bonded to the hose liner. The method includes receiving the material in the fitting, drawing the hose liner through the fitting, and bonding the material to the hose liner such that the hose liner and material are secured to an outer face of the fitting.
The attached drawing figures provide additional disclosure:
As shown in detail B, the face 303 of the end fitting 301 includes a concave sealing gasket groove 307 formed therein.
Groove 302 is formed in groove 307. The groove 302 is shown having a lower edge at the surface of groove 307 that is a predetermined radial distance R1 from axis A-A. In one embodiment where the end fitting 301 has a nominal diameter of 1 inch, the radius R1 is about 1.538 inches. The groove 302 is configured to retain a ring 304 of melt-processable material therein. In at least one embodiment, the end fitting 301 can be formed from a metal, such as stainless steel, and the grooves 307 and 302 may be formed in the face 303, such as by machining, casting, and the like. Of course, in other embodiments, other materials may be used to form the end fitting 301. Moreover, while the groove 302 is shown in
The groove 302 is shown formed having a generally square or rectangular shape extending in a direction at a predetermined angle θ with respect to axis A-A. The groove 302 is formed having a predetermined width w and depth D. The dimensions of the groove 302 are configured to retain the ring 304 therein, such as by friction or compression fit, such that the ring 304 will not tend to fall out of the groove 302 prior to or during processing of the fitting 301 and hose, described herein. For example, in one embodiment, the ring 304 is constructed so that the inner radius of the ring 304 is less than the dimension R1 of the fitting 301. Once stretched beyond the edge of the groove 304 at dimension R1, the ring 304 can be inserted into the groove 302. The resiliency of the ring 304 will tend to keep the ring 304 in the groove 302 and, therefore, the ring 304 will not tend to fall out of the groove 302 prior to or during processing of the fitting 301 and hose, described earlier.
The angle θ of the groove 302 with respect to axis A-A can be an acute angle and is preferably between 30 and 45 degrees. In one embodiment, the groove 302 is configured to at least partially receive an o-ring 304 having a predetermined cross-sectional diameter which can vary, for example, between 0.035 and 0.060 inches, depending on the nominal size and configuration of the end fitting 301. In one embodiment where the end fitting 301 has a nominal diameter of 1 inch, the o-ring has an annular diameter of 1.5 inches and has a cross-sectional diameter of about 0.060 inches. The inside radius of the ring 304 is made smaller than the dimension R1 of the fitting 301. Once snapped into groove, the ring 304 will not tend to fall out of the groove 302 prior to or during processing of the fitting 301 and hose, described earlier.
The annular width Wa (
In the case of sanitary fittings constructed in compliance with ASME BPE 2009, the shapes of the groove 302, as well as their location on the face 303, may be selected based upon the nominal inner diameter of the hose assembly, and the arrangement of standard sized sanitary style fittings corresponding to the nominal inner hose diameter. For example, arrangement of the groove 302 shown in
As shown in
In one embodiment, the ring 304 is formed of a material which can be molded to the shape of the groove 302 while also being bonded to a material used for the hose liner 401 (
As shown in
In other alternative embodiments the groove 302 may also have a curved shape, including teardrop (
Another embodiment of an end fitting 301 is shown in
Also, as shown in
As shown in
A method of manufacturing a lined hose will now be described. In one embodiment of the method, an end fitting 301, constructed in accordance with the first aspect, is provided and a hose liner 401 is drawn through the end fitting 301. In one embodiment, the hose liner 401 is drawn concurrently through a hose carcass (not shown) and the end fitting 301. The method also includes introducing the melt-processable ring 304 into the groove 302. The hose liner 401 is drawn through the end fitting 301 outwardly from the face 303 a certain distance sufficient to flare the drawn end of the liner 401 over the face 303 of the end fitting 301. The drawn end of the liner 401 is heated to a gel state and is flared radially outwardly onto the face 303, preferably using a hydraulic operated balloon which inflates from within the end of the hose liner 401 to spread the liner 401 toward the sealing face 303 of the end fitting 301.
While the sealing face 303 is in the gel state, a grooving tool 701 (
A forming head 801, an example of which is shown in
While retained against the surface 402, forming head 801 and at least a portion of the end fitting 301 are inserted into a salt bath that is maintained at a predetermined temperature for a predetermined duration up to a depth covering the sanitary clamp holding the forming head 801 to the end fitting 301. In an exemplary embodiment, where a flared 1 inch stainless steel end fitting 301 is configured as shown in
While still compressed together, the end fitting 301 and the forming head 801 of the hose assembly are inserted into a cooling bath, comprised of, for example, water, to a predetermined depth, measured inwardly from the sealing surface 402, for a predetermined amount of time. At the end of that predetermined amount of time, the end fitting 301 and forming head 801 are immersed to a greater depth in the cooling bath, such as down to the second end 309 (
In one embodiment, the forming head 801 can be configured with a thermal mass at a longitudinally outward end of the forming head 801 which is sufficient to act as a heat sink that can keep the longitudinally inner portions of hose liner 401, which are surrounded by the body portion 300a of the end fitting 301, from being heated above a certain temperature, while concentrating the heat transferred from the salt bath at the sealing surface 402 and the sealing flange 306, in order to melt the ring 304 and the flared liner 402 and bond the them together, as shown in
A comparison was made between two different hose/end fitting connections using a nominal 1 inch diameter hose of a type available under the trademark Stratus from Crane Co. (smooth PTFE inner core, and platinum-cured silicone with stainless-steel wire and fabric reinforcement) after soaking each end fitting connection for 15 seconds in dye penetrant (Kingscote fluorescent red tracer dye item #106023 FWT 25). One end fitting 301 was configured in accordance with an embodiment described above using a dual-grooved fitting 301, the PTFE liner bonded to a melt-processable PFA o-ring molded in the groove 302 of the fitting 301. A second end fitting did not include a PFA O-ring at all. The end fitting face 303/sealing surface 402 interface at the first end fitting showed a flatter sealing surface 402 than compared to the second end fitting. In the latter instance, the flared face which did not have a PFA o-ring bonded thereto consequently displayed a characteristic wavy appearance and separation from the sealing face 303 of the end fitting 301. In the case of the first tested configuration, it was found that in between the sealing surface 402 and the face 303 penetrant did not move moved radially inward past the PFA o-ring. In the case of the second configuration without the ring 304 bonded to the sealing flange 402, it was found that in between the sealing surface 402 and the face 303 penetrant was detected radially inwardly past the radial distance of the ring 302 in the first configuration. In this latter case, close clearances between the sealing surface 402 and the face 303 captured and restrained the penetrant from draining when the flared end fitting was removed from the soaking solution.
While the present invention has been described with respect to various embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, the invention is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
This application claims the benefit of priority under 35 U.S.C. §119(e) to U.S. Provisional Application No. 61/223,957, filed on Jul. 8, 2009, the entire contents of which are incorporated by reference herein.
Number | Date | Country | |
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61223957 | Jul 2009 | US |