GB2301579A

GB2301579A - Sampling device

Info

Publication number: GB2301579A
Application number: GB9511069A
Authority: GB
Inventors: Michael Frank Clarke; Anthony Blackwell
Original assignee: Flex Rite Hose & Couplings Ltd
Current assignee: Flex Rite Hose & Couplings Ltd
Priority date: 1995-06-01
Filing date: 1995-06-01
Publication date: 1996-12-11
Anticipated expiration: 2015-06-01
Also published as: GB2301579B; GB9511069D0

Abstract

A sampling device for fluids in the form of a syringe with a vessel (20) having a hollow spindle (25) extending from one end with lateral holes (25a) for the entry/exit of fluid. A sleeve (28) surrounds the spindle (25) to close the holes (25a) and is retractable towards the vessel to reveal the lateral holes, whereby the volume of the vessel (20) remains constant during filling.

Description

SAMPLING DEVICE The present invention relates to a sampling device for extracting a volume of fluid from a vessel or conduit containing the fluid. Sampling devices of this type are used in a wide range of fluid handling and processing systems in a variety of technical fields including food and drink production and handling of chemicals and pharmaceuticals. The present invention is particularly applicable to sampling devices of the type including a syringe for extraction of fluid.

As is well known, a syringe typically consists of a cylindrical vessel having a hollow spindle extending from one end via which fluid may enter the vessel and a circular plunger which is slidable within the vessel to define a sample volume. A sample is taken by inserting the spindle into the fluid and sliding the plunger with respect to the cylindrical vessel to draw fluid into the vessel.

For certain applications, in order to avoid contamination or leakage of the sample, the spindle must be sealed as it is withdrawn from the fluid. This has been achieved in the past by making the spindle movable with respect to the cylindrical vessel and providing an additional sleeve closely surrounding the spindle which is fixed with respect to the cylindrical vessel. The spindle has a closed end and lateral holes for the entry and exit of fluid By the use of suitable springs, the spindle is retracted into the sleeve as it is removed from the fluid so that the lateral holes are covered by the sleeve. A disadvantage of this arrangement is that a part of the spindle enters the sample volume as it is retracted, thus increasing the pressure within the sample volume.Even with a small spindle compared to the size of the vessel, this increase in pressure can be hazardous when attempting to discharge the sample. Thus, it would be advantageous to provide a "constant pressure" sampler.

Syringe-type samplers are typically provided with cooperating valve assemblies which are attached to the conduit or vessel containing the fluid to be sampled. Typically, an operator has to coordinate the opening of the valve with the insertion of the spindle to avoid spillage of fluid. It would be advantageous to provide a syringe which was operable to open a fluid release valve on insertion of the spindle into the vessel or conduits.

One aspect of the present invention provides a fluid sampler comprising a vessel having a hollow spindle extending from one end, the spindle being closed at its end remote from the vessel and having lateral holes for the entry of fluid; and a sleeve surrounding the spindle to close the lateral holes; the spindle being fixed with respect to the vessel and the sleeve being retractable towards the vessel to reveal the holes.

It will be appreciated that the sampler thus described may be of the syringe-type including a plunger slidably mounted in the vessel to define a sample volume.

Preferably means are provided for biasing the sleeve towards the end of the spindle to close the lateral holes, such as a spring for example.

The sampler may be adapted to be screwed into a mating shroud provided as part of a valve assembly. For example, the vessel may have a closure, such as a cap, from which the spindle extends, having cam surfaces for cooperating with cam followers provided in the shroud, The sampler may also be provided with a screw-on transport cover and/or a screw-on discharge cover for discharging the sample.

This invention also provides a sampling device comprising a fluid sampler as described above and a valve assembly for attachment to a conduit or vessel containing the fluid to be sampled. The surface of the sleeve remote from the vessel may abut against a cooperating surface of the valve assembly, whereby when the sampler is pushed in the axial direction of the spindle, the sleeve is pushed towards the vessel.

Another aspect of this invention provides a sampling device, comprising a fluid sampler for collecting the sample and a valve assembly for attachment to a conduit or vessel containing the fluid to be sampled, the fluid sampler again comprising a vessel from which a hollow spindle extends and the valve assembly including a valve member which closes an exit port for the fluid, wherein the insertion of the spindle into the valve assembly is arranged to cause the valve member to move away from the exit port. Thus, there is no need for a separate valve operating lever, for example. The valve is simply opened on insertion ofthe spindle into the valve assembly.

It should be clear from the foregoing that the invention enables the provision of a sampling device including a fluid sampler, such as a syringe, and a valve assembly, in which the fluid sampler and the valve are opened in one movement.

As noted above, the valve assembly may include a shroud for guiding the insertion of the sampler. Preferably the shroud and sampler have cooperating means enabling the shroud to be rotated with respect to the sampler or vice versa to cause axial movement of the sampler with respect to the shroud. Such means may comprise matching screw threads or cam surfaces and cam followers on the shroud and sampler or vice versa.

The cooperating means (e.g. screw threads, cam surfaces, cam followers) may be provided on a closure of the vessel from which the spindle extends in which case the valve assembly may have additional means for guiding the insertion of the spindle, such as a location boss.

The location boss and spindle sleeve preferably have respective means for preventing rotation of the sleeve with respect to the location boss. These may comprise pins on one engaged in slots in the other.

Preferably the shroud is rotatable with respect to the location boss. Preferably the shroud has slots matching the slots in the sleeve or boss and the slots are provided in the sleeve or boss or shroud at several different orientations so that the sampler may be inserted into the valve assembly with the shroud at a selected one of the several orientations. Thus, if the shroud is provided with a lever enabling it to be rotated, the orientation can.be selected according to the space available for the lever.

The arrangement may be such that when the sampler has been fitted in the valve assembly, the shroud is rotatable with respect to the location boss to retain the sampler in place before taking a sample. Thus the same lever used to rotate the shroud also operates to secure the sampler with respect to the valve assembly. This is in contrast to several known sampling devices of this type.

An embodiment of the invention will now be described by way of example only and with reference to the accompanying drawings in which: Figure 1 is a front elevation, partly in section, showing a sampling device according to the invention including a valve assembly and a syringe, with the syringe just inserted into the valve assembly and the valve closed; Figure 2 is a front elevation, partly in section, showing the sampling device of Figure 1 with the valve open, the syringe plunger pulled back and the sample vessel full; Figure 3 is a side elevation corresponding to Figure 1; Figure 4 is an enlarged part sectional view of the valve assembly only; Figure 5 is an enlarged sectional view of the syringe only; Figure 6 is a cross-section taken on the line A-A of Figure 3; Figure 7 is a cross sectional view of a cover for use in removing the sample from the syringe; and Figure 8 is a cross-sectional view of a transport cover for the syringe.

The drawings show a sampling device comprising a valve assembly and a fluid sampler in the form of a syringe. The valve assembly is positioned in a fluid conduit or pipe. The pipe is shown in dotted lines in Figure 3. In practice, the valve assembly acts as a junction between two lengths of pipe. The coupling of the valve assembly to the pipes is conventional and will not be described further herein.

The valve assembly includes a valve body 10 and valve actuator 11. The valve body includes a through passage for fluid in the direction perpendicular to the plane of Figures 1 and 2. The valve body includes an exit port 12. The exit port is normally closed by valve member 13 mounted on shaft 14 and biased by spring 15 forming part of the actuator 11. The valve assembly further comprises a locking shroud 18 designed to receive the syringe, to be described in more detail below.

The syringe, shown most clearly in Figure 5 includes a cylinder 20, made from glass in this example, in which a plunger 21 is slidably mounted. An end cap 22 limits the retraction of the plunger 21. The plunger has a shaft 21 a which passes through the end cap 22. The shaft 21a is provided with a handle 21b for manual operation of the syringe.

The cylinder is protected by a metal coversleeve 23 having a viewing slot 23a. The cap 22 is screwed into the coversleeve 23. The upper end of the cylinder 20 as shown has a cap 24 from which a hollow spindle 25 extends. The cap 24 has a central hole so that the interior of the spindle communicates with the interior of the glass cylinder. An interior seal 26 between the cap 24 and the glass cylinder 20 ensures that there is no leakage of fluid.

The spindle 25 is closed at its end remote from the plunger and has lateral holes 25a for entry and exit of fluid. Preferably there are four holes at equally spaced locations around the surface of the spindle. The spindle 25 is surrounded by a closely fitting cylindrical sleeve 28 which is received in an annular slot in the cap 24. The end of the spindle 25 and the valve member 13 have opposing abutting surfaces. The sleeve 28 bears against an opposing surface of the valve body 10. A spring 29, caught in an annular space between the spindle 25 and sleeve 28, biases the sleeve in the forward direction to close the lateral holes 25a. A seal 30 provided in the end of the spindle sleeve 28 ensures effective sealing ofthe holes 25a. The seals 26 and 30 may be made from PTFE for example.The spindle carries two pins 31 and 32 at diametrically opposed locations whose function will be described below.

The cap 24 is adapted to be screwed into the locking shroud 18 in a manner to be described in more detail below. For this purpose the cap has opposed cam surfaces in the form of deep 1/4 turn screw threads indicated at 33 and 34 in Figure 3.

Referring now to Figures 1 and 4, the valve body 10 is provided with a cylindrical location boss 40 for receiving the sleeve 28. The location boss is fixed with respect to the valve body 10 and may be permanently attached to it. The location boss 40 has eight diametrically opposed slots 50 for receiving the pins 31, 32 of the sleeve 28 whereby, once inserted, the sleeve 28 is not rotatable with respect to the location boss 40.

The locking shroud 18 is rotatably secured with respect to the location boss 40 by means of an end flange 45 on the location boss 40 received in an annular recess 46 provided on the locking shroud 18 (see Figure 4). A lever 47 is provided for rotating the locking shroud -18 (this is omitted from Figures 2 and 4 for the sake of clarity). The shroud 18 is formed to include a circular plate 49 which abuts against the end flange 45 of the location boss 40. The plate is provided with two diametrically opposed slots 42 and 43 indicated by dotted lines in Figure 4, also sized to receive pins 31, 32 of sleeve 28.

The shroud is provided with two cam followers or rollers 52, 53 which are secured to the locking shroud 18 by means of screws so as to be rotatable about an axis perpendicular to the spindle axis. (One roller is omitted from Figure 1.) The sampling device is assembled and operated as follows: Having installed the valve assembly in a fluid conduit, the locking shroud 18 is rotated so that the two slots 42, 43 in plate 49 are aligned with a pair of slots 50 in the location boss 40. This can be in any one of eight alternative angular orientations of the locking shroud 18. A suitable orientation is selected such that the lever 47 can be turned through 1/4 turn. Surrounding pipework, for example, may limit the number of suitable positions.

The syringe is then offered up to the locking shroud 18 and the sleeve 28 inserted in the location boss so that the pins 31 and 32 pass through the slots in the plate 49 and enter the slots 50 in the location boss 40. The locking shroud is then rotated by about 10 using lever 47, so that the slotted plate 49 rotates with respect to location boss 40 and the pins 31, 32 are caught between the plate 49 and location boss 40. This position is shown in Figure 1. At this point the operator no longer needs to hold the syringe in place. The shroud 18 is designed so that at this point the cam followers 52, 53 have just met the cam surfaces 33, 34 so that on further rotation ofthe locking shroud the cam surfaces define the axial position of the syringe.

In order to take a sample the lever 47 is further rotated through 90" whereby the cam followers 52, 53 on the locking shroud 18 travel along the cam surfaces of the cap 24 of the cylindrical vessel 20. The camping action causes the spindle 25, which is fixed with respect to cap 24, to be pushed upwardly as shown in the drawings, thereby pushing valve member 13 upwardly and opening the exit port 12.

During this operation, the sleeve 28 is held stationery by the opposing face of the valve body 10. This position is shown in Figure 2. It will be noted that springs 15 and 29 are compressed.

The cam surfaces 33 and 34 end in slight indentations to secure the syringe in the 'valve open' position. One indentation, 34a, is illustrated in Figure 3.

Once the valve is open, fluid can flow into the vessel 20 via holes 25a in spindle 25. Depending on the pressure and viscosity of the fluid in the conduit, it may or may not be necessary to manually withdraw plunger 21 in order to cause fluid to flow into the cylinder. Once the cylinder contains the desired amount of fluid, the lever 47 is turned back by 1/4 turn, and the reverse camming action occurs. The valve member 13 is pushed back over exit port 12 by spring 15 and the sleeve 28 is pushed upwardly to cover the holes 25a by the action of spring 29. Internal stops in the sleeve 28, not shown in the drawings, ensure that the sleeve is flush with the end of the spindle when the syringe is dosed.

It should be noted that the opposing surfaces of the spindle 25 and the valve member 13 are flat faces. This ensures, as near as possible, drip free operation of the syringe. As the valve member 13 closes the exit port, 12, any fluid between the valve member and the exit port is squeezed back into the fluid conduit. Once the flat faces of the spindle 25 and valve member 13 are separated there is no fluid between them because they have been in continuous contact. The design of the sampling device is such that the holes 25a are covered by the seal 30 in the spindle sleeve 28 before the flat faces are separated. Thus,the syringe is fully closed with the sample safely contained before the syringe is removed from the valve assembly.

It should also be noted that the flat faces of the spindle 25 and valve member 13 remain stationary with respect to each other, once in contact. There is no rotation of one with respect to the other which would cause the surfaces to wear. Only the locking shroud is rotated, causing the entire syringe to travel in the axial direction towards the valve assembly.

It should also be noted that on disengagement of the spindle from the valve member 13, there is no increase in the pressure of the sample because the sample volume, formed by the cylinder 20 and the spindle 25, remains constant.

The use of a single lever for both engagement of the syringe itself and then opening of the valve renders the whole sampling operation extremely convenient. After initial insertion of the syringe into the valve assembly, no axial force is required to operate the device.

The components of the sampling device may be made from a variety of materials depending on the particular application. In the illustrated example, shaded parts are T?\) typically metal, such as hastelloy or stalnless steel, and double shaded parts are PTFE.

The particular materials will be chosen to be compatible with the product to be sampled.

Once the syringe has been removed from the valve assembly the sample itself can only be discharged after the sleeve 28 has been retracted to expose the holes 25a. The spring 29 is preferably sufficiently strong that this cannot be achieved manually, to avoid accidental discharge of the sample. Instead, the syringe is provided with a discharge cover 60, illustrated in Figure 7. The cover is suitably shaped to fit over the sleeve 28 and has pins 61, 62 which engage the cam surfaces on the syringe cap 24.

The cover includes an insert 65 providing an annular shoulder 66, which bears against the sleeve in use. The insert provides a first cylindrical portion 68 whose internal diameter is greater that the external diameter of the spindle and a second cylindrical portion 69 from which sampled product is discharged. In order to discharge the product from the syringe, the cover 60 is screwed onto the syringe cap 24 so that it acts in the same way as the locking shroud 18, causing the seal 30 of sleeve 28 to bear against the shoulder 66 and compressing spring 29. The sample can then be discharged using plunger handle 21b. The product passes between the spindle 25 and the cylindrical portion 68 and out via the cylindrical portion 69. The contact between the seal 30 and shoulder 66 ensures that the product does not flow backwards. It will be appreciated that Figure 7 simply shows one example of a discharge cover suitable for use with the syringe.

Figure 8 shows a transport cover 70 for the syringe. The cover 70 includes a stopper 75 to prevent the escape of fluid and pins 71, 72 to engage the cam surfaces of the syringe cap 24. The cover is simply screwed over the syringe cap and the sleeve 28 remain stationary with respect to the spindle 25 whereby no product is discharged.

Claims

CLAIMS:

1. A fluid sampler comprising a vessel having a hollow spindle extending from one end, the spindle being closed at its end remote from the vessel and having lateral holes for the entry of fluid; anda sleeve surrounding the spindle to close the lateral holes, the spindle being fixed with respect to the vessel and the sleeve being retractable towards the vessel to reveal the lateral holes.

2. A fluid sampler as claimed in claim 1 including means for biassing the sleeve towards the end of the spindle to close the lateral holes.

3. A fluid sampler as claimed iD claim 1 or 2 including a plunger slidably mounted in the vessel to define a sample volume.

4. A fluid sampler as claimed in claim 1,2 or 3 adapted to be screwed into a mating shroud.

5. A fluid sampler as claimed in claim 4 in which the vessel has an integral or removable cap from which the spindle extends and the cap has cam surfaces for cooperating with cam followers provided in the shroud.

6. A sampling device comprising a fluid sampler as claimed in claim 1,2 or 3 for collecting the sample and a valve assembly for attachment to a conduit or vessel containing the fluid to be sampled.

7. A sampling device as claimed in claim 6 in which the surface of the sleeve remote from the vessel abuts against a cooperating surface of the valve assembly, in use, whereby when the sampler is pushed in the axial direction of the spindle. the sleeve is retracted.

8. A sampling device as claimed in claim 7 or 8 in which the valve assembly is provided with a shroud for guiding the insertion of the sampler.

9. A sampling device as claimed in claim 8 in which the sampler and shroud have cooperating means enabling the sampler to be rotated with respect to the shroud to cause axial movement of the sampler with respect to the shroud.

10. A sampling device as claimed in claim 9 in which the sampler and shroud have cooperating screw threads.

11. A sampling device as claimed in claim 9 in which the sampler has cam followers for cooperating with cam surfaces on the shroud or vice versa.

12. A sampling device as claimed in claim 9,10 or 11 in which the cooperating means is provided on a closure of the vessel from which the spindle extends and the valve assembly has additional means for guiding the insertion of the spindle.

1 3. A sampling device as claimed in claim 12 in which the spindle guide or location boss and the spindle sleeve have means for preventing rotation of the spindle with respect to the boss.

14. A sampling device as claimed in claim 13 in which the rotation prevention means comprise pins on one of the spindle and boss engaging slots in the other.

15. A sampling device as claimed in any of claims 8 to 14 in which the shroud is rotatable with respect to the location boss.

1 6. A sampling device as claimed in any of claims 8 to 1 5 in which the shroud has slots matching the slots in the sleeve or boss with the slots in the sleeve or boss or shroud being provided at several different orientations so that the sampler may be inserted into the valve assembly with the shroud at a selected one of the orientations.

17. A fluid sampler substantially as hereinbefore described with reference to the accompanying drawings.