DE7422685U - faucet - Google Patents

Description

PATENT Attorney DR.-INGS. H. FINCKE DIP L. -ING. H. BOHR DIPL.-INQ. S. STAEGER

Long-distance call * 24 40 40 Telegromm: Claim MOnchun Poiltchectkontoi Munich 27044

Bank details Bay.r. Vereiiwbonk MOnchwi, account £ »404

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MOIIeritroee 31

3rd July 1974

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No. P 26252

IMPERIAL CHEMICAL INDUSTRIES LIMITED,

Imperial Chemical House,

Millbank

London SW1P 3JF / UK

"Faucet"

PRIORITY: July 03, 1973 - UK

The innovation relates to a tap for the regulation of the "flow of a fluid and in particular to tap spindles, which can be manufactured easily and cheaply and with which the flow of a liquid in a laboratory facility, such as a burette _f can be regulated.

The subject of the innovation is a tap for regulating the flow of a fluid, consisting of a body with a

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Cock seat and with a passage through the seat as well as a spindle arranged inside the body, which thereby geksniiseiCiiiiOt is, ds.2 the spindle ~? eir ^ ?? Ebrn "it e **"? ** ring-shaped Groove in which an elastic ring is arranged, and from an inert sleeve that sits tightly on the surface of the end part of the mandrel sits and covers the elastic ring, there is a closed sleeve Has end part that fits into the valve seat and can close it, and one via the elastic ring having annular sealing portion protruding from the surface of the remainder of the sleeve, the annular Sealing part is pressed against the surrounding body, so that a sliding seal is formed.

The end part of the mandrel on which the sleeve is firmly attached, preferably has a cylindrical surface to provide good support for the side walls of the sleeve to achieve, while keeping a dead space between the valve body and the spindle as small as possible will.

According to a preferred embodiment, the elastic ring on the spindle consists of an O-ring, the outer Diameter is larger than the diameter of the dome, so that the annular part of the sleeve through the O-ring outside so that it rises above the surface of the remainder of the sleeve. Sine such a spindle can thereby be made by placing an O-ring in an annular groove running around a mandrel, and inserting the mandrel and the O-ring into a sleeve whose inner diameter is smaller than or equal to like the diameter of the cathedral. Since the diameter of the O-ring is larger than the diameter of the dome, it pushes an annular part drawn over the mandrel

outside, so that the annular part stands out from the rest of the sleeve surface. By keeping the sleeve this way

gen part of the sleeve against the faucet body so that a good seal is obtained, but it also provides a means by which the sleeve is held at the end portion of the mandrel.

An alternative method of making the stem of such a faucet is to place the sleeve on the mandrel and the To manufacture an O-ring by injection molding, for example by applying a thermoplastic material by injection molding, the shape being designed so that the sleeve follows the contours of the mandrel and the O-ring, with the annular part of the sleeve overlying the O-ring, is shaped so that it protrudes from the rest of the surface. However, if a sleeve over c * n mandrel and a protruding O-ring is sprayed on from one end of the spindle, then when using a wide groove the Tendency for the O-ring to be pushed back into the groove, the front of the groove being filled with the injection compound. This presents a disadvantage, namely the elasticity of the annular sealing part relative to the tap body is reduced. It is therefore preferred to equalize the size of the O-ring and the groove so that the O-ring fits tightly in the groove and against the groove Ingress of injection molding compound prevented during the manufacture of the sleeve around the mandrel and the O-ring by injection molding will.

The above build-up of injection molding compound is enhanced by the fact that the O-ring protrudes from the mandrel surface. He can be reduced by ensuring that the elastic ring is flush with the Bornoberfläehe or

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that the surface of the elastic ring is slightly below the surface of the cathedral. In another execution crm of the cock, in which of cLIe ^ eT- fact Q-euse is made and which is therefore particularly suitable for producing the sleeve by injection molding in situ one in which the surface of the elastic ring is flush with the surface of the mandrel surface or even underneath, the sleeve having a protruding annular rib overlying the elastic ring and thereby forming the protruding Ringdichtungstexl.

With all these spindles, whether they are using a pre-fabricated sleeve with an annular part that goes through an O-ring is forced outwards, or by injection molding the sleeve in situ, it is preferred Provide means by which the sleeve is retained on the mandrel. Whether this is absolutely necessary depends partly from the materials used for the sleeve, O-ring and mandrel and partly from the pressure gradient on the seal when using the tap. For example, when using materials with a very low coefficient of friction used for the sleeve (such as PTFE), or if a very much lower pressure inside the Hahns than outside (for example in an evacuated device), then it becomes increasingly important to provide a special means of retention. Under the usual conditions, however, the friction between the sleeve and the mandrel are sufficient to hold the sleeve in place. With a low pressure difference, such as in a burette cock prevails, the holding that results from the fact that the sleeve protrudes through a can be sufficient O-ring is printed outwards. If other means of retention are required then suitably include

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an anchoring of the sleeve on the mandrel. Such an anchorage can be obtained very easily on spindles where the sleeve is formed in situ by making another Provides recess (also such as, for example, another annular groove) in the surface of the spindle and into this recess inserts an anchor that is integral with the remainder of the sleeve.

In all forms of the present faucet, the sleeve separates the mandrel and the resilient ring from a fluid flowing through the faucet. Both the mandrel and the elastic ring can therefore be made of the most physically suitable materials, regardless of the fluid that will flow through the tap and whether this could corrode these materials. Suitable materials are, for example, brass or nylon filled with glass for the mandrel and rubber for the elastic ring. However, the material used for the sleeve must be inert to the fluid because the fluid and the sleeve will come into contact with one another during use of the faucet. Materials that are suitable for the manufacture of the sleeve are, for example, nylon and polyolefins. However, because of their inertness to a wide range of chemical compounds, fluorine-containing polymers are generally preferred. These also have the advantage of having a low coefficient of friction, which makes it easier to operate the taps. Of the fluorine-containing polymers, polytetrafluoroethylene / hexafluoropropylene mixed polymers (FEP) in particular can be used to produce a preformed sleeve or to produce a sleeve in situ by injection molding . Polytetrafluoroethylene (PTEP) is particularly suitable for pre-formed sleeves.

The innovation is now based on special
Embodiments of the innovation based on the "attached
Drawings explained in more detail.

In the drawings show:

Pig. 1 shows a section through a burette stopcock, in which the spindle was made using a pre-fabricated sleeve;

Fig. 2 is a section through a mandrel with alternatives
Features that act as a replacement spindle for the tap
of Figure 1 can be used;

Fig. 3 is a section through a spindle, which a

has injection molded in situ sleeve; and

FIG. 4 shows a section through a burette stopcock, which is similar to that of FIG. 1, but has a spindle (not cut), as shown in FIG. 3
you can see.

The tap of FIG. 1 has a body 1 made of glass which has a bore with a smooth surface and is provided with a tap seat 2 at one end. The other end of the body has an external thread 3. Entry and exit arms 4, 5 open into the bore of the body, one above the valve seat. The cock spindle has a mandrel 11, in the end part of which an annular one
Groove 12 is incorporated. An elastic O-ring 13 made of rubber is arranged in the groove, the outer part of which protrudes beyond the cylindrical surface of the dome. The end of the dome is covered by a tightly fitting sleeve 14 made of PTFE

surrounded, the thin side walls 15 and a more massive Has end 16, the latter being shaped to fit into the cock seat 2. The mandrel has 2 at the other end Lugs 17. A cap 18 is applied to this end of the well, which has slots which the lugs 17 be able to record. The cap is held in place by a screw 19.

When assembling the spindle, the O-ring 13 pressed over the end of the dome until it is seated in the groove 12. While the closed end of the sleeve by hand is held, the side walls of the sleeve moderately heated to expand them. Then they are pressed over the mandrel and the O-ring while they are warm until the mandrel contacts the closed end of the sleeve. Then the cap 18 is applied to the end of the dome and fastened with the screw 19. After inserting the spindle into the bore of the body and after screwing it on the cap on the thread of the body 1, the tap is ready. It can then be built into a laboratory device will. The Haan can be operated in the usual way by turning the cap, due to the thread between the cap and the body, the spindle moves axially to and from the cock seat 2 when it is rotated.

An annular portion of the side walls of the sleeve is expanded outwardly by the O-ring and pressed against the iijiere surface of the bore of the body to form a seal. When looking through the gas body, the seal can be seen as an approximately 1 mm wide ring. This Dichtimg looks wet as wünie dae glass by the PTFE in the area of the O-ring.

PTFE is the preferred material for a preformed sleeve of this type because it has high chemical inertness and

Ginen shows low coefficient of friction. Also the physical properties of this material result in a very good suitability in the present case. So this is Material sufficiently elastic so that a sufficient seal of the valve seat is obtained and that small deviations be compensated in the wall of the bore in order to achieve a seal. Earlier experiences go there that sleeves made of materials with such low friction are supported by a similar ^ part (piston, subjected to a high vacuum exposed), have been suctioned from the mandrel during operation, provided they are not in any Way was attached. It has now been found, surprisingly, that with the more restricted movements, which usually occur when a rooster is struck, the sleeve is held firmly in place in many laboratory applications and exhibits sufficient tear strength without further retaining means must be provided.

Faucets of various sizes were made, all of which were essentially the same shape as it explained above. The cocks tested had holes in the body from 7.16 to 25 »40 mm. This area includes the mainly occurring laboratory glassware. All had PTFE sleeves that were mounted on glass-filled nylon mandrels sat, which had annular grooves 0.94 mm - 0.04 mm deep and 2.03 mm wide, in which O-rings with 1.78 mm thick. With these materials and dimensions it has been shown that the inner diameter of the Sleeve should preferably be the same or slightly smaller than the diameter of the "^ orns νοι · the assembly, so the sleeve is held firmly in place in applications such as burette taps. However, in more severe conditions, it is preferred a sleeve with a smaller inner diameter

use. A mandrel having a diameter 1 to 3 > larger than the interior diameter of the sleeve prior to assembly is generally more preferred. The side walls of the PTFE sleeve in the area of the O-ring were preferably less than 0.63 mm thick, since thicker PTFE walls, as it turned out, did not hold the O-ring as well. Side wall thicknesses below 0.3 mm have made sleeves more difficult to handle, so it is preferred to use sleeves in which the side walls are now at least 0.3 mm thick. The most suitable inside diameters for standard rubber O-rings, nominally 1.78mm thick, are 80 to 90 # of the mandrel diameter at the base of the groove.

Sin like in fig? The faucet shown in Figure 1 was tested to determine the effectiveness of the sealing of the stem, which is achieved by the annular portion of the PTFE sleeve being pressed against the body. The cock had the following dimensions:
Diameter of the bore 7.16 mm,
Outer diameter of the PTFE sleeve 6.86 mm, thickness of the sleeve side walls 0.51 mm, thickness of the O-ring 1.78 mm,
Inner diameter of the O-ring 3.68 mm and diameter of the mandrel at the base of the groove 3.81 mm. The test was carried out by connecting the tap to a large evacuated container and measuring the time during which the pressure increased by a certain amount. In the present case, one arm of the tap was sealed while the other arm was connected to a container with a capacity of 1 liter, with the tap in the open position. The container was equipped with a device to evacuate it. Furthermore, a Pirani measuring instrument was used to measure

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solution of the internal pressure arranged. After the normal degassing process there was a seal between the spindle

-7 3 -1 and the body of more than 5 x 10 torr dm see,

while the pressure in the container from 10 "" ^ to 2 χ 10 Torr rose.

The O-ring used in the tap was a commercially available one Ring. A thickness of 1.78-0.08 mm is generally suitable for most laboratory device applications. Other thicknesses currently available are 2.62 mm and 3.53 mm. These can be used with other dimensional tolerances. True seals are good with larger thicknesses can also be achieved with small taps, but an excessive groove depth weakens the mandrel and can be unsuitable for mechanical reasons. Therefore the usual standard O-rings with a thickness of 1.78 mm preferred for taps of laboratory equipment. The O-ring used in the above experiments had one circular cross-section, as these are generally more readily available. However, O-rings can also be used other cross-sectional shapes can be used, which should also give good results.

The faucet was a simple faucet suitable for regulating the flow of liquid through laboratory glassware. He was relatively cheap and easily mass-produced. As a result it became a construction where only a small amount of the relatively expensive PTFE is required. The spindle owns no provision whatsoever for adjusting the external pressure to the number of those to be made and assembled To keep parts small. As a result, despite the elasticity of the O-rings, which have a small tolerance in the diameter

knife in the bore of the body allows the size of the annular, outwardly pressed part in about the Corresponding to the size of the diameter of the ears. For the scheme the liquid flow at atmospheric pressures, For example, in a burette, a lower precision with the usual pipe sizes does not cause any problems.

r> As the above results show, it is when the above Sizes are roughly adhered to, possible an extremely good seal even with high pressure differences at the tap to achieve. However, if temperature fluctuations have to be taken into account, especially if still a high one If the pressure difference at the tap is added, then it is preferred to replace the spindle with a more complex one according to the innovation Replace the spindle on which the expansion can be adjusted. One such spindle is for example in the GB-PS 1 15? 620 described.

It is not absolutely necessary to use PTFE for the sleeve. In particular thermoplastic materials can be deformed into very cheap sleeves. An overly flexible material is due to the expansion O-ring not held in place tightly enough. For example, a test tap with dimensions made similar to those of the one described above, the passage rates of which were also measured, but replacing the PTPE sleeve with a polypropylene sleeve was. This sleeve was also held in place satisfactorily and provided an adequate seal. This However, the tap was harder to turn than the one with PTFE. But since the pitch of the thread in the cap - as shown - was relatively small, this tap was also completely satisfactory in use.

using a two-part Foxa with a cylindrical chamber that has an annular κ "« τια "? on the outside

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Had surface, tap spindles were also made by placing a sleeve over a mandrel and an O-ring * was pritäggossen. The mandrel and G-in were as in Figure 1, except that the mandrel was on the side of the O-ring that was facing away from the nose, had a step, the step increasing the radius by the thickness of the sleeve. The thorn and the O-ring was then placed in the mold with the O-ring seated in the annular channel in the mold. On that Polypropylene was injected into the mold from the spindle nose, leaving an even layer on the mandrel and formed the O-ring up to the shoulder. There was an even layer exactly where the O-ring was away from the mandrel of the sleeve according to the contours of the dome and the O-ring also an annular part that was spaced from the rest of the part. Although some flags were visible where the the two molded parts butted against each other, the protruding sealing part of this spindle also appeared to be uniform across the glass to "wet" the perimeter. The burette stopcock obtained behaved very similarly to the one using the preformed polypropylene sleeve had been produced according to the above procedure.

FIG. 2 shows in section a mandrel with two independent features which cannot be seen in FIG. Every feature can be used individually with advantage. It is an air discharge tube 21 and an extension 22 with an undercut at the end of the cap of the dome. Own the other parts the same reference numerals as in Fig. 1. The air discharge pipe is a pipe which is the one closed by the sleeve The end of the dome connects to the atmosphere, leaving the trapped air during assembly can escape more easily than is the case if it has to pass the O-ring. In general, it is extremely useful to provide an axial tube as shown, however

the tube can of course be arranged in other locations, provided that it allows the air to escape. The undercut approach is provided so that the cap can be pulled open by a snap action can. The cap can be the same as in Pig. Be 1. The snap action makes it possible, however, that the screw 19 can be omitted, which requires that the mandrel pierced and prepared to receive the screw must become.

The shoulders 17 are provided to prevent rotation of the mandrel with respect to the cap. In most In cases this is not essential as the spindle is free along the bore with no rotational movement corresponding to the rotational movement the cap can slide when the latter is rotated, opposed to axial movement due to the thread to achieve the tap body. If rotation of the mandrel is not essential, the shoulders can be omitted.

An alternative embodiment of taps, which can also be found in laboratory glassware, is one in which the two arms (corresponding to the arms 4 and 5 shown) are in alignment. The valve body, which includes the spindle, then runs perpendicular to it. The cock is closed by inserting the spindle between the two A: * me, so that they are sealed off at the same time by the side walls of the spindle. Such faucets are much more expensive to be effective because the seat of the spindle in the closed position must be precise and as this is generally more expensive than making a seat at the mouth of a single arm which is coaxial with the spindle and so directed is that it can be closed by the end of the spindle as shown in FIG. Last-

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rer tap with a single lockable ann is therefore preferred when a cheap tap is required.

The spindle of Figure 3 has a mandrel 31 made of glass filled nylon. In an annular Groove that runs around the mandrel, a ring 32 of rubber is inserted, the surface of which with the surface of the cathedral. In the vicinity of the ring 32 there is another annular groove 33. All around At the end of the mandrel is a sleeve 34 made in situ from polypropylene by injection molding is. The closed end of the sleeve is shaped so that a solid nose 35 is formed. On the opposite of the nose At the end, the polypropylene is closed in the groove 33 during molding, so that an anchorage 36 was created is. Located around the spindle and above the ring 32 there is a rib 37. The end of the spindle facing away from the sleeve is axially pierced and threaded Mistake. There is also a shoulder 38 which extends outward on both sides.

In Fig. 4 it can be seen that the spindle is inserted in a tap body 41, the two arms 42 and 43 and one Has cock 44. A cap 45 is through a screw 46 attached to spindle 46 and fits snugly over shoulders 38. The cap is threaded which mates with threads 47 engages the body so that when the cap is rotated the spindle nose will move to and from seat 44 moved away. The cock is closed by pressing the spindle nose 35 against the seat 44 is moved.

The inside diameter of the faucet body was 10.54 mm and the

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Diameter of the rib on the spindle 10.92 mm, so that when Inserting the spindle into the faucet body the rib was pressed against the rubber ring 32, which thus the rib constantly pressed outwards against the faucet body, making a seal was achieved. The purpose of the seal is to prevent any fluid from passing through the Tap flows along the side of the spindle towards the cap. Therefore, through the sleeve 34 in An effective isolation of the dome from the fluid, the flow of which is being regulated, is achieved in the region of the rib.

EXPECTATIONS:

Claims (1)

CLAIMS s I. Cock for regulating the flow of a fluid, "consisting of j from a body with a cock seat and with a passage through the seat as well as an interior of the body j arranged spindle, characterized in that the spindle consists of a mandrel (11) with a; annular groove (12) in which an elastic ring; (13) is arranged, and from an inert sleeve (14),! which sits tightly on the surface of the end part of the dome j (11) and covers the elastic ring (13), consists, the sleeve having a closed end part (16) which fits into the cock seat (2) and can close it, -and over the elastic ring one having annular sealing part, d ^ r of the Surface of the rest of the sleeve (H) protrudes, the annular sealing part against the surrounding Body (1) is pressed, so that a sliding seal is formed. _e tap according to claim 1, characterized in that the sleeve is anchored on the mandrel so that> it cannot be pulled down. | 3. tap according to claim 1 or 2, characterized g e k e η η - ' shows that the elastic ring (13) consists of an O-ring, the outer diameter of which is larger let than the diameter of the mandrel, so that an annular Part of the sleeve that lies over the O-ring, is printed outwards so that it stands out over the rest the surface of the sleeve rises. Tap according to Claim 1 or 2, characterized in that the surface of the elastic Ring with the surface of the dome (31) fluclrcet or lies below the surface of the Born (31), and that the sleeve has a protruding annular rib (37), wherein the rib overlies the resilient ring and forms the protruding annular sealing portion. PATENlAlM «V ALIc K. FINOE, DIPL-JNG. H. MPUNhI-IMHiI