GB2384828A

GB2384828A - Sampling device

Info

Publication number: GB2384828A
Application number: GB0123510A
Authority: GB
Inventors: Richard James Brawn
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-09-29
Filing date: 2001-09-29
Publication date: 2003-08-06
Anticipated expiration: 2021-09-29
Also published as: GB2384828B; GB0123510D0

Abstract

A sampling device for one handed operation comprises a cylindrical barrel 2 to hold the sample with a nozzle 4 at a first end 3, two guide pillars 7 extend longitudinally from an open end of the barrel 2, and a thumb pad 9 is detachably connected to a remote end of the pillars 7. A piston unit 11 is moveable longitudinally within the barrel 2 and has a grip 14 provided with apertures 19 to accept the guide pillars 7, where by manual force applied to the thumb pad and the grip 14 to urge them one towards the other causes a vacuum at the nozzle 4.

Description

SAMPLING DEVICE The present invention relates to a device for taking samples of liquids. More particularly, but not exclusively, it relates to a device operable with one hand for controllably taking measured samples of liquid.

In many applications, it is necessary to take a sample of known size from a larger quantity of liquid, for example for testing purposes. In some cases, a graduated syringe may be adequate to the task, but in many other cases it suffers from distinct problems.

One such task is testing fuel, and in particular jet aviation fuel, to check its undissolved ("free") water content. Jet fuel with too high a free water content can damage aircraft fuel systems. A simple, well-established test for free water content entails passing a fuel sample of known volume (normally five millilitres) through a disc of filter paper treated with water sensitive chemicals. The presence of undissolved water is indicated by a change in colour of the centre portion of the detector paper. The test paper reacts at very low levels of water

contamination, even below 10 parts per million ("ppm"), by changing colour. It changes progressively from a faint y & w/green at lower water contamination levels to a distinct green colour when the water content is approximately 30ppm, indicting positive water contamination.

The test is currently carried out by holding the test paper in a sample capsule, which is mounted on to the nozzle of a graduated syringe. The fuel is drawn through the capsule, and thus through the test paper, and into the syringe by withdrawing the syringe's plunger, until exactly five millilitres have been drawn into the syringe's graduated barrel. The colour of the test paper is then checked, the sample capsule and test paper are removed, and the fuel sample is discarded.

However, there are drawbacks to this method. The impregnated test paper, through which the fuel must pass, is of low permeability, and so-there is resistance to drawing the sample into the syringe. A standard syringe is designed to expel its contents controllably, being operable by pressing on a pad on the end of a plunger with a thumb, while hooking two fingers under flanges extending outwardly from the barrel. The plunger can thus be pressed home with a single controllable motion. The syringe can thus be operated with one hand.

It is usually necessary to use both hands to draw a sample into the syringe, one holding the barrel and the other pulling the plunger. The necessary force can thus be applied, but not in a particularly controllable manner. A two-handed pull, strong enough to overcome the resistance of, for example, the test paper, may lead to too large a sample being taken, a target graduation mark on the barrel being overshot before the pull can be stopped. It may also lead to a jerky movement of the plunger within the barrel. It is very important that exactly the

right sample volume is drawn through the test paper, particularly in borderline cases. A significantly strong or sudden pull may even pull the plunger out of the barrel entirely, spoiling the test and potentially splashing highly flammable fuel around. Operating the syringe two-handed with caution. to avoid such problems, slows the test considerably. In addition, use of a standard syringe necessitates the hands of the user coming into close proximity or even contact with the fuel being tested.

Powered syringes and pipettes are known, but they are considerably more expensive and complex, may not be safe for use with highly flammable liquids, and do not, as a whole, generate enough force or suction to overcome the resistance of test papers such as are used in the aviation fuel test described above.

It is therefore an object of the present invention to provide a sampling device, operable with one hand, for controllably ta1., ig a fluid sample. of measured volume, which obviates the problems described above and allows rapid, reliable and safe sampling operation, whilst keeping the user's hands clear of the fuel.

According to the present invention, there is provided a sampling device for fluids adapted for one handed operation and comprising an elongate substantially cylindrical barrel to hold the sample, inlet means at a first end thereof, guide means extending longitudinally from a second open end thereof, a manually operable plunger means connected to a remote end of the guide means, piston means moveable longitudinally within the barrel and having manually operable grip means co-operable with and moveable with respect to the guide means and extending, at least in part, radially outwardly thereof, whereby manual force applied to the plunger means and the grip means to cause them to move one towards the other

initiates such relative movement of the piston means within the barrel as to apply a vacuum to the inlet means, thereby drawing up a sample.

The grip means may be provided with aperture means configured to accept the guide means slideably therethrough.

The plunger means is preferably adapted so that a thumb of the hand of the user may be pressed to a surface thereof.

Alternatively or additionally, it may be adapted so that a palm of the hand of the user and particularly a ball of the thumb of the user may be pressed to the surface thereof.

The grip means is advantageously adapted so that at least one optionally two, fingers of the hand of the user may be pressed to a surface thereof.

The hand of the user may thu., 1Je closed, bringing said finger or fingers, and said thumb or palm each toward the other and so exerting forces respectively on the piston means and the barrel.

The piston means may comprise a piston head with sealing means to contact sealingly an interior surface of said barrel.

The guide means may comprise a plurality of elongate members extending from respective points equally spaced around the open second end of said barrel.

Said elongate members may comprise extensions of the wall of said barrel, optionally having an arcuate cross-section continuous with said wall.

There may be two said elongate members.

The inlet means may comprise nozzle means, to which further elements, such as filter means, needle means, tubing means or test media holding means may be mounted.

The barrel may be provided with indicia to measure a volume of fluid drawn thereinto.

An embodiment of the present invention will now be more particularly described, by way of example and with reference to the accompanying drawings, in which: Figure 1A, 1B and 1C show, in elevation, components of a sampling device embodying the invention; Figure 2 is a scrap perspective view of an open end of the component of Figure 1 A ; Figure 3 is a plan view of the end of the component of Figure I C ; Figure 4A shows a sampling device comprising the components of Figures 1A, IB and 1 C, ready for use; and Figure 4B shows the sampling device of Figure 4A in use.

Turning now to the drawings and to Figure 1 A in particular, a barrel unit I of a sampling device comprises a hollow elongate cylinder 2, closed at its distal end 3 except for a nozzle 4. The cylinder 2 is provided with two elongate slots 5, extending longitudinally from an open end 6 of the cylinder 2, and on diametrically opposite sides thereof. Figure 2 shows in

perspective the open end 6 of the cylinder 2 in more detail. The two diametrically opposed slots 5 separate the cylinder 2 into two opposing pillars 7 of arcuate cross-section.

Figure I B shows a cap 8, comprising a thumb pad 9 and a plug section 10, adapted to fit into the open end 6 of the cylinder 2. The plug section 10 can be secured in place by a screw thread, by a detent or can be a friction fit into the cylinder 2.

Figure 1 C shows a piston unit 11 comprising a piston head 12 at one end of a shaft 13 of generally cruciform cross-section and a generally disc shaped handle 14 at the other end of the shaft 13. The piston head 12 and the shaft 13 are dimensioned to fit closely within the cylinder 2 of the barrel unit, and the piston head 12 is provided with a circumferential sealing ring 15 to provide an air-and liquid-tight seal against an inner surface of the cylinder 2.

As shown more clearly in Figure 3, the handle 14 of the piston unit comprises two arcuate apertures 19 defined by an outer ring 16, a central disc 17 forming an end of the shaft 13 and connecting bars 18. Each bar 18 fits slideably within a respective slot 5 of the barrel unit 1.

Finger grippable lugs may be provided on opposed sides of the outer ring 16.

The sampling device is assembled by loading the piston unit 11 into the open end 6 of the barrel unit 1, with the outer ring 16 of the handle 14 disposed outside the cylinder 2 and the pillars 7 located within the arcuate apertures 19. The piston unit 11 is of sufficient overall length that the piston head 12 contacts the closed end 3 of the cylinder 2.

Once the piston unit 11 has been loaded into the barrel unit 1, the plug section 10 of the cap 8 is inserted into the open end 6 of the cylinder 2. The sampling device is now ready for use.

Figure 4A shows the sampling device before use with a testing capsule 20 mounted to the nozzle 4, so that liquid drawn through the capsule 20 and into the nozzle 4 has to pass through a test paper treated with water sensitive chemicals. The piston unit 11 is disposed as shown by dotted line 21 in Figure 4A with the piston head 12 being close to or in contact with the closed end 3 of the barrel unit 1.

To operate the sampling device, a user places a thumb against a thumb pad 9 and two fingers of the same hand against a distal surface of the outer ring 16 of the handle 14. The user gently brings his or her fingers and thumb towards one another exerting forces in the direction of arrows 22 and 2 : -, As a result, the outer ring 16 and the thumb pad 9 move towards one another, so that the piston unit 11 moves relatively outwardly, creating suction which draws liquid through the testing capsule 20 into the sample device.

The resistance of the test paper in the capsule 20 can be overcome by gradually increasing the force exerted to close the user's hand and bring the fingers and thumb together, until the piston unit 11 begins to move. It is easy to exert just enough force and no more with such a hand-closing motion. As the handle 14 is constrained to travel along the pillars 7, the piston unit 11 remains aligned with the barrel unit 1, however far it travels, and the forces exerted remain substantially aligned with the longitudinal axis of the sample device, ensuring that the operation of the device is balanced and controllable.

The piston unit 11 can then be moved until it reaches the disposition shown by dotted line 24, in Figure 4B, where its end is level with a preselected graduation mark 25 on the barrel unit 1, and a required volume of liquid has been drawn into the sampling device. It is easy to halt a controlled hand-closing motion accurately at such a chosen point.

With the required volume of liquid having been drawn through the test paper into the sampling device, the test paper can now be checked for a yellow to green colour change. The testing capsule 20 can be removed from the nozzle and discarded. The sampling device can be emptied for re-use by pushing the handle 14 or pulling the thumb pad 9. No particular control is required over this operation, so a sharp two-handed motion will suffice.

While the use of the sampling device is described above in terms of drawing a sample through a low-permeability test paper, such a sampling device would also be of use if accurately-measured samples are to be taken through narrow constrictions, or of viscous fluids, such that significant resistance needs to be overcome to draw in the sample. Even for sampling low-viscosity fluids, if accuracy of drawing in a sample is more important than controllability of expulsion, a sampling device of this type may well be preferable to a conventional syringe.

The sample device shown is also simple and cheap to manufacturer, being only marginally more complex than a conventional syringe. It can thus be used in circumstances where it may need to be disposed of after a limited number of uses, where economics would compel cleaning, repair and re-use of more complex devices.

Claims

CLAIMS: I. A sampling device for fluids adapted for one handed operation comprising an elongate barrel to hold a sample, inlet means at a first end thereof, guide means extending longitudinally from a second open end thereof, manually operable plunger means connected to a remote end of the guide means, piston means moveable longitudinally within the barrel and having manually operable grip means co-operable with and moveable with respect to the guide means and extending, at least in part, radially outwardly thereof, whereby manual force applied to the plunger means and the grip means to urge them one towards the other produces such relative movement of the piston means within the barrel as to apply a vacuum to the inlet means, thereby drawing up a sample therethrough.
2. A sampling device as claimed in claim 1, wherein the grip means is provided with aperture means configured to accept the guide means slideably therethrough.
3. A sampling device as claimed in either claim I or claim 2, wherein the plunger means is adapted so that a palm of a hand of a user and particularly a ball of a thumb of the user may be pressed to a surface thereof.
4. A device as claimed in claim 3, wherein said surface is oriented generally away from the barrel of the device.
5. A device as claimed in any one of the preceding claims, wherein the grip means is adapted so that at least one finger of a hand of a user may be pressed to a contact surface thereof.
6. A device as claimed in claim 5, wherein said contact surface is oriented generally towards the barrel of the device.
7. A device as claimed in any one of the preceding claims, wherein the guide means comprises a plurality of elongate members extending from respective points equally spaced around a periphery of the open second end of said barrel.

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8. A device as claimed in claim 7, wherein said elongate members comprise extensions of the wall of said barrel
9. A device as claimed in either claim 7 or claim 8, wherein there are two said elongate members.
10. A device as claimed in any one of the preceding claims, wherein the plunger means comprises pressure pad means mounted to the remote end of the guide means.
11. A device as claimed in any one of the preceding claims, wherein the plunger means is detachably mounted to the guide means.
12. A sampling device as claimed in any one of the preceding claims, wherein the barrel is substantially cylindrical.
13. A device as claimed in any one of the preceding claims, wherein the barrel is provided with indicia to measure a volume of fluid drawn thereinto.
14. A device as claimed in any one of the preceding claims, wherein the inlet means is provided with mounting means for further elements, such as filter means, needle means, tubing means or test media holding means, to be mountable detachably thereto.
15. A device as claimed in any one of the preceding claims, further comprising filter means, needle means, tubing means or test media holding means mounted detachably to the inlet means thereof.
16. A sampling device for fluids substantially as described herein with reference to the Figures of the accompanying drawings.