GB2451128A

GB2451128A - A stopper for a bottle

Info

Publication number: GB2451128A
Application number: GB0714151A
Authority: GB
Inventors: Brian William Thomson Hepburn
Original assignee: CHRISTABEL BARRON HEPBURN
Current assignee: CHRISTABEL BARRON HEPBURN
Priority date: 2007-07-19
Filing date: 2007-07-19
Publication date: 2009-01-21
Anticipated expiration: 2027-07-19
Also published as: GB0714151D0; GB2451128B

Abstract

A Biochemical Oxygen Demand (BOD) testing bottle (1), the bottle comprising a mouth (5) and the bottle having a stopper (15) located in the mouth (5) for inhibiting fluid communication into and out of the bottle (1) through the mouth (5). The stopper comprises a fluid displacing element (23), arranged to displace fluid in the bottle in the region of the mouth, and the bottle and stopper comprise complementary screw threads (9a-c, 21a-c) for holding the stopper in the mouth so as to form a seal between the stopper and the bottle. The bottle may have an elongate neck portion (7) for inhibiting bubble formation when a probe is interted into the bottle.

Description

1 2451128 A bottle

Technical Field

The present invention relates to bottles and particularly, but not exclusively, to Biochemical Oxygen Demand (BOD) testing bottles.

Background of the Invention

It is often desirable, particularly in a laboratory environment, for a bottle to be easily and reliably sealed to prevent transfer of fluid into and out of the bottle.

Biochemical Oxygen Demand (BOD) testing (sometimes referred to as Biological Oxygen Demand testing) used, for example to measure water pollution, is an example of a laboratory environment in which the contents of a bottle must be reliably sealed from the surrounding air. In BOD testing, a bottle is filled with a sample (for example a water sample), and then sealed. To obtain meaningful results from the BOD testing, it is important that oxygen does not enter or leave the bottle once a sample has been taken. It is also important that the bottle is completely filled (i.e. that no air remains above the sample) once the bottle has been sealed.

For BOD testing, it is common practice to collect the samples in relatively thick-walled glass bottles. Once the oxygen content of the sample has been measured (for example by inserting a probe into the bottle), the glass bottle is then sealed. The bottle is typically sealed by inserting a frusto-conical glass stopper into the mouth of the bottle. The stopper is shaped so as to displace any air/liquid in the bottle in the region of the mouth and therefore ensures that the bottle is completely filled once the stopper has been inserted. The weight of the glass stopper is sufficient to maintain a seal and prevent ingress of oxygen into the bottle through the mouth, and the glass itself is sufficiently impermeable to air to prevent any oxygen being transferred through the walls of the bottle. After a set period of time, the bottle is opened and the oxygen content of the sample is re-measured. The change in oxygen content of the sample may, for example, be used to give a measure of the level of pollution in a water sample.

The glass bottles and stoppers described above are relatively expensive to manufacture and may also be susceptible to breakage. However, there has been a strong reluctance in the industry to consider materials other than glass, as those materials are thought to have been permeable to oxygen. There has also been a strong reluctance to consider other types, or shapes of bottle. Some other types of bottle have been suggested (including some non-glass -bottles), but these have been found to be susceptible to ingress of oxygen due to, for example, a poor seal being formed after the sample has been taken.

As mentioned above, in BOO testing, once a sample has been taken (but before the bottle has been sealed), a probe is inserted into the bottle to measure the oxygen content of the water. The probe tends to be used to stir the sample.

However, this has been found to sometimes lead to bubbles forming in the bottle, and particularly the neck of the bottle. The formation of bubbles in the bottle is undesirable as, if they are trapped in the bottle once it has been sealed, their presence may affect the results of the BOD testing.

The present invention seeks to remove or mitigate at least one of the above-mentioned problems. The present invention seeks to provide an improved bottle, and particularly, but not exclusively, an improved BOO testing bottle.

Summary of the Invention

According to a first aspect of the invention, there is provided a bottle for storing fluids, the bottle comprising a mouth and the bottle having a stopper located in the mouth for inhibiting fluid communication into and out of the bottle through the mouth, wherein the stopper comprises a fluid displacing element arranged to displace fluid in the bottle in the region of the mouth, and the bottle and stopper comprise complementary screw threads for holding the stopper in the mouth so as to form a seal between the stopper and the bottle. Such an arrangement has been found to be particularly useful in a laboratory environment where a number of applications require a stopper having an element for displacing fluid in a bottle, but also require an effective and reliable seal between the bottle and the stopper.

The bottle is preferably a Biochemical Oxygen Demand (BOO) testing bottle. As will be understood by the skilled person, only bottles having particular characteristics are suitable for such a use. For example, the bottle, when sealed should be substantially impermeable to oxygen (for example through the material from which the bottle is made, and/or through the seal at the mouth of the bottle). The bottle should preferably be sealable in a simple and effective way, without requiring complex processes or tools so that the bottle can be sealed at the location and time at which the sample is taken.

The bottle should preferably be repeatably sealable using the stopper.

The bottle may be made of plastics material. The stopper may be made of plastics material. Both the bottle and the stopper may be made of plastics material. Manufacturing the bottle and/or stopper from plastics material, may enable the bottle to be relatively cheap to manufacture and/or easy to transport. It has traditionally been considered impractical to use a bottle and/or stopper of plastics material in BOD testing because plastics materials were thought to be too permeable to oxygen. However, it has now been identified, that some plastics materials are in fact sufficiently impermeable to oxygen to be suitable for this application.

Thus, the use of certain plastics materials in BOD testing does itself go against conventional thinking in the art.

It has been found that embodiments of the present invention in which the bottle and/or stopper are made of plastics material, and in which the bottle and stopper comprise complementary screw threads for holding the stopper in the mouth, are particularly beneficial because the plastics material tends not to be heavy enough to form a seal between the bottle and the stopper through its weight alone (as would be the case for known arrangements using glass stoppers).

Thus embodiments of the invention may enable an effective and reliable seal to be formed between the stopper and the bottle, whilst also realising at least some of the cost and manufacturing benefits obtained by using plastics material.

In an embodiment in which the bottle is of plastics material, the region of the bottle containing the screw thread may be supplied separately to the other parts of the bottle and simply joined to the bottle during manufacture. This embodiment of the invention is therefore particularly attractive due to relatively low manufacturing costs.

The plastics material itself is preferably substantially oxygen-impermeable. The plastics material preferably has an oxygen permeability of less than 50 cm3/mm/m2 (over 24 hours at atmospheric pressure). More preferably, the plastics material has an oxygen permeability of less than 20 cm3/mm/m2, and yet more preferably of less than 10 cm3/mrn/m2. The plastics material preferably requires no additional treatment(s) (such as irradiating with an electron-beam) to ensure sufficient impermeability to oxygen. The plastics material may be Polyethylene terephthalate (PET).

The stopper is preferably able to be applied to, or released from, the bottle by the user without need of additional tools or complex machinery. The stopper preferably comprises a grip portion to facilitate twisting of the stopper by a user. The grip portion may be any number of shapes to assist the user in opening and closing the bottle, but is preferably in the form of a heptagon (when viewed from above).

The fluid displacing element of the stopper may take a number of forms, but is preferably a generally fustro-conical form. The fluid displacing element preferably extends below the thread on the stopper. When the stopper is located in the mouth of the bottle, the fluid displacing element preferably extends below the thread on the bottle. When the stopper is located in the mouth of the bottle, the fluid displacing element preferably extends into the neck portion of the bottle. The fluid displacing element may displace over 50%, and more preferably over 75%, of the fluid in the region of the stopper.

When the stopper is held in the mouth of the bottle, a seal may be formed in a variety of ways, but the seal is preferably formed at an annular contact area at, or near, the top of the fluid displacing element. An effective seal may be facilitated by the inherent deformability of the bottle and/or stopper material. For example, in an embodiment in which the stopper is made of plastics material, the stopper may have a maximum diameter slightly greater than that of the mouth of the bottle, and the material may be sufficiently deformable to form an effective, resilient, seal when held in the mouth by the complementary screw threads.

It will be appreciated that the screw threads on the bottle and/or stopper need not necessarily be continuous, or both be in a helical arrangement. For example, in the embodiment described below with reference to the accompanying drawings, the screw thread on the stopper merely comprises three equally-spaced planar ridges which engage the helical screw thread on the bottle.

The stopper may comprise a marker element (such as a coloured disc) for indicating the particular use, or contents, of the bottle. The marker is preferably located on the top of the stopper. The marker may also perform a structural function; for example due to the nature of the manufacture of the stopper, the top of the fluid displacing element of the stopper may otherwise be open, and the marker may close off this opening.

According to another aspect of the invention, there is provided a stopper for use as the stopper in the bottle according to any aspect of the invention described herein, the stopper comprising a fluid displacing element for displacing fluid in the bottle in the region of the mouth and a threaded portion for engagement with a complementary thread on the bottle. The stopper may have benefits when used on any one of a variety of bottles and not necessarily just bottles as described with reference to embodiments of the present invention. Indeed, the threaded portion on the stopper is preferably arranged to engage a complementary threaded portion on a variety of different bottles. The stopper may therefore be used in a number of applications, particularly in a laboratory environment. The stopper according to the above-

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mentioned aspect of the invention may be especially beneficial for certain laboratory applications.

The bottle according to embodiments of the present invention is preferably of a particular shape to make it well suited for BOO testing. The bottle preferably comprises a voluminous main body portion. An elongate neck portion preferably connects the main body portion to the mouth.

The bottle may be dimensioned so as to mitigate bubble formation when liquid in the bottle is stirred (for example when a probe is inserted into the neck of the bottle). It has been found that by providing the bottle with a particularly elongate neck portion, the likelihood of bubble formation is reduced.

Thus according to yet another aspect of the invention, there is provided a BOD testing bottle, the bottle comprising a mouth and the bottle having a stopper located in the mouth for inhibiting fluid communication into and out of the bottle through the mouth, wherein the stopper comprises a fluid displacing element arranged to displace fluid in the bottle in the region of the mouth, and wherein the bottle comprises a voluminous main body portion and an elongate neck portion connecting the main body portion with the mouth, the elongate neck portion being so shaped to inhibit bubble formation in the neck portion, when a probe is inserted into, and agitates, a sample in the bottle.

The ratio of the height of elongate neck portion to the height of the bottle may be between 2.50:1 and 3.50:1. The ratio of the height of elongate neck portion to the height of the bottle, may be more than 2.70:1, more preferably more than 2.80:1 and yet more preferably 2.90:1. The ratio of the height of elongate neck portion to the height of the bottle

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may be less than 3.30:1, more preferably less than 3.20:1 and yet more preferably 3.10:1. The ratio of the height of elongate neck portion to the height of the bottle is preferably around 3.0:1.

The neck portion may be comprise a circular cylindrical region. The main body portion may comprise a circular cylindrical region. Alternatively or additionally, the main body portion may comprise and a tapered region, the tapered region joining the main body portion to the neck portion.

The elongate neck portion preferably has a maximum outside diameter of less than 45.0mm, more preferably less than 40.0mm, and yet more preferably less than 38.0mm. The elongate neck portion preferably has a maximum outside diameter of more than 25.0mm, more preferably more than 30.0mm, and yet more preferably more than 34.0mm. The diameter will be readily identifiable, and it will be appreciated that the elongate neck portion need not necessarily be of circular cross-section in order to have a diameter. In the event that the elongate neck portion is not of circular cross-section, the diameter will be understood to be the largest dimension in the plane normal to the longitudinal axis of the neck portion.

The height of the neck portion may be less than 55.0mm, more preferably less than 50.0mm, and yet more preferably less than 45.0mm. The height of the neck portion may be more than 25mm, more preferably more than 30mm, and yet more preferably more than 35mm. An elongate neck portion having a height between 35.0mm and 45.0mm has been found to be particularly effective in inhibiting bubble formation.

The main body portion preferably has a maximum outside diameter of less than 85.0mm, more preferably less than 80mm, and yet more preferably less than 75.0mm. The main body portion preferably has a maximum outside diameter of more than

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50.0mm, more preferably more than 60.0mm, and yet more preferably more than 65.0mm. The maximum outside diameter of the main body portion is preferably around 71mm, since this corresponds to the standard dimensions used in a number of factory-line machines in the industry. The diameter of the main body portion will be readily identifiable, and it will be appreciated that the main body portion need not necessarily be of circular cross-section in order to have a diameter. In the event that the main body portion is not of circular cross-section, the diameter will be understood to be the largest dimension in the plane normal to the longitudinal axis of the main body portion.

The height of the main body portion may be less than 100.0mm, more preferably less than 90.0mm, and yet more preferably less than 85.0mm. The height of the main body portion may be more than 60.0mm, more preferably more than 70.0mm, and yet more preferably more than 75.0mm.

In embodiments of the invention comprising a tapered region, the tapered region may comprise a surface of varying slope (for example the tapered region may comprise a rounded shoulder). Preferably however, the tapered region comprises a surface having a substantially constant slope.

According to yet another aspect of the invention, there is provided a method of obtaining a sample for Biochemical Oxygen Demand (BOD) testing, comprising the steps of: filling a bottle with the sample to be tested, placing a stopper in the mouth of the bottle, the stopper comprising a fluid displacing element for displacing fluid in the mouth of the bottle, and twisting the stopper relative to the bottle to engage complementary screw threads on the bottle and the stopper so as to draw the bottle and the stopper together, forming a seal between the stopper and the bottle. The method of obtaining a -10 -sample for BOO testing may, of course be part of a complete BOD test. For example, other steps associated with the method of obtaining a sample may include one or more of: measuring the oxygen content of the sample, waiting, after the bottle has been sealed, for a certain period of time and then removing the stopper and re-measuring the oxygen content of the sample. The sample is preferably a water sample.

There is also provided a method of obtaining data in a Biochemical Oxygen Demand (BOO) test, the method comprising the steps of: filling a bottle with a sample to be tested, the bottle comprising an elongate neck portion, inserting a probe into the elongate neck portion of the bottle to measure the oxygen content of the sample, the elongate neck being so shaped to inhibit bubble formation in the neck portion upon stirring of the probe.

Each of the above described methods of the invention may comprise the step of providing a bottle according to any aspect of the invention described herein.

It will be appreciated that any features described with reference to one aspect of the invention are equally applicable to another aspect of the invention. By way of example, the bottle according to the first aspect of the invention may include any of the dimensions specified herein.

The bottle comprising an elongate neck portion may include a screw thread for engagement with a complementary screw thread on the stopper such that the stopper may be held in the mouth of the bottle.

Description of the Drawings

-11 -Various embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings of which: Figure 1 is a perspective view of the bottle without the stopper; Figure 2 is a side view of the bottle without the stopper; Figure 3 is a perspective view of the stopper from above; Figure 4 is a perspective view of the stopper from below; Figure 5 is a view of the underside of the stopper; Figure 6 is a sectional view through the stopper; Figure 7 is a perspective view of the bottle with the stopper located in the mouth; Figure 8 is a side view of the bottle and stopper of Figure 7; and Figure 9 is a sectional view through the bottle and stopper of Figures 7 and 8.

Detailed Description

Biochemical Oxygen Demand (BOD) testing can be used to measure pollution in waterways such as streams, and domestic water supplies. An exemplary BOO testing method is described below in which a known, glass, BOD testing bottle is used.

The first step is to fill the glass bottle with a water sample. The bottle typically is filled up to its mouth.

Next, a probe is inserted into the bottle through the mouth.

The probe is used to stir the water sample, and takes a reading of the oxygen content of the water. Once the reading has been taken, the probe is removed and the bottle is sealed to prevent any oxygen entering or leaving the bottle (which -12 -To seal the bottle, a solid glass stopper is placed into the mouth of the bottle thereby forming a seal (under the action of its own weight) between the stopper and the bottle.

After a certain period of time, the bottle is re-opened and a probe is inserted to measure the oxygen content of the water sample. The change in the oxygen content of the sample over the period of time can be used to calculate the degree of pollution of the water.

The known, glass, BOD testing bottle has a main body portion and a neck portion. The main body is generally cylindrical and has a diameter of 70mm and height of 104mm.

The neck portion is also cylindrical and has an inner diameter of just under around 24mm, and a height of 26mm.

It tends to be accepted practice to use glass bottles in BOD testing, as it is accepted that the oxygen permeability of glass is sufficiently low to not adversely affect the results of the SOD test. There is therefore a reluctance to move away from using glass. However, glass bottles are relatively expensive and can be difficult to transport or store.

Another problem with the bottle described above is that there is a tendency for air bubbles to be created when the probe is used to stir the water sample. These air bubbles can be trapped in the bottle when it is sealed and will adversely affect the BOD test.

Figures 1 and 2 show a BOD testing bottle 1 according to a first embodiment of the invention. The bottle 1 comprises a relatively voluminous main body portion 3, a mouth 5, and an elongate neck portion 7 connecting the main body portion 3 with the mouth 5.

The main body portion 3 comprises a lower part 3a in the form of a right circular cylinder and an upper part in the form of a conical frustum 3b. The right circular cylinder 3a has an outside diameter of D of 71.00mm. This diameter is -13 -particularly useful as it is a standard diameter accepted by a number of factory line machines used during assembly/manufacture of the bottle. The main body portion 3 has a height H of 83.20mm. The base of the main body portion 3 is concave and comprises a star-shaped rib 13 (shown in dashed line in Figure 2) for improving the strength and rigidity of the bottle.

The upper part 3a of the main body portion is joined to the neck portion 7. The neck portion 7 is relatively elongate and is in the form of a right circular cylinder having an outside diameter d of 36.40mm and a height h of 40.50mm. The top of the neck portion 7 defines the mouth 5 of the bottle 1.

The outer surface of the neck portion that surrounds the mouth includes a screw-threaded region 9 integrally formed with the bottle. The screw-threaded region includes three helical ridges 9a, 9b, 9c extending around the mouth, and a circular flange 11 below the threaded region 9. The bottle has a wall thickness of around 0.5mm (although this the wall is a little thicker in places, such as around the mouth).

The bottle is made of transparent Polyethylene terephthalate (PET). PET is chosen because it is relatively cheap and enables the bottle to be cheaply manufactured by blow-moulding. PET has also been found to have a sufficiently low oxygen permeability (of around 9 cm3/rnm/m2) to be suitable for use in BOO testing. In the first embodiment of the invention, the oxygen permeability of PET is sufficiently low that there is no need for additional surface treatments (such as electron beam radiation).

Figures 3 to 6 show a stopper 15 for use with the bottle 1 of Figures 1 and 2. The stopper 15 is also made of PET, but in this case the PET is coloured red, rather than being transparent.

-14 -The upper part of the stopper 15 comprises a heptagonal grip portion 17 to facilitate the user manipulating the stopper. The grip portion extends downwardly, away from the top surface of the stopper 15. The stopper 15 comprises a threaded ring 19 which also extends downwardly from the underside of the top surface of the stopper. The threaded ring 19 and the heptagonal grip portion 17 are concentric, but the grip portion 17 extends beyond the ring 19 so as to form a curtain surrounding the threaded ring 19.

The inner diameter dr of the threaded ring is 38.30nutt.

The threaded ring includes three substantially planar ribs 21a, 21b, 21c, equally spaced about its radially-inner surface. These ribs define the screw threads on the stopper 15.

The stopper 15 also comprises a fluid displacing element 23 in the form of a frusto-conical portion extending downwardly away from the upper surface of the stopper 15. The fluid displacing element 23 is located radially inwardly of the threaded ring 19 (and of the grip portion 17), and is concentric therewith. The top of the fluid displacing element 23 (i.e. the part nearest the upper surface of the stopper) has an outside diameter db of 33.40mm. The sides of the fluid displacing element are inclined at an angle a of 16 degrees to the vertical and the fluid displacing element has a height hb of 30.50mm. The fluid displacing element 23 is arranged to displace fluid in the region of the mouth of the bottle in which the stopper is located. Thus, if the bottle is not quite full of a sample (as may be the case if a probe had just been inserted into the bottle) the fluid displacing element displaces any remaining air above the sample, together with some of the sample, itself to ensure that no air bubbles remain in the bottle once it has been sealed.

-15 -The fluid displacing element itself is hollow and opens to the top of the stopper at an opening 25. During manufacture of the stopper, a thin plastic disc 27 (shown only in cross-section in Figures 6 and 9) is inserted into the opening and held by way of a snap-fit. The disc 27 not only covers the top of the displacing element 23 to prevent dirt or foreign bodies collecting inside it, but also acts as a marker to indicate the contents of the bottle, or the nature of its use. Various different coloured discs can be placed in the lid in dependence on the use of the bottle. In the first embodiment of the invention, the disc is blue. The disc can be replaced with a different coloured disc in the event that the bottle is used for a different purpose.

Figures 7 to 9 show the stopper located in the mouth of the bottle. The threaded ring 19, being of a larger diameter than the mouth of the bottle, is located outside the mouth.

The three ribs 21a, 21b, 21c on the threaded ring 19 of the Stopper 15 are arranged to engage the complementary helical threads 9a, 9b and 9c on the threaded region 9 on the outer surface of the neck portion 7 of the bottle 1. Thus, by twisting the stopper 15, the bottle 1 and stopper 15 are drawn together. The outer diameter of the top of the fluid displacing element 23 is slightly greater than the inner diameter of the mouth 5, therefore a seal is formed between the top of the fluid displacing element 23 and the bottle 1 as the stopper and bottle are drawn together.

In the present invention, a reliable and effective seal is formed by the bottle and stopper being drawn together by the complementary screw threads 21a-c, 9a-c. As the stopper is held by the screw threads, and not purely retained by its own weight, the stopper can be made from a lighter material (for example a plastics material such as PET in this case).

This allows the bottle and stopper to be manufactured more -16 -cheaply than some known BOD testing bottles, whilst not adversely affecting the performance of the bottle in BOD testing.

The arrangement of the elongate neck portion 7 has also been found to be particularly advantageous. It has been found that by providing an especially elongate neck portion (for example a neck portion of between 35 and 45mm), bubble formation is reduced when a probe (not shown) is inserted into the neck and used to stir, or otherwise agitate, the sample.

The elongate neck is thought to reduce the size of the vortex which tends to form in the neck, when a probe is inserted and stirred. This has been found to reduce bubble formation in the neck (in comparison to shorter neck portions as described above with reference to the known glass BOD bottle). By reducing the chances of bubbles forming in the neck, the BOD test is more likely to produce a reliable and accurate result.

A method of BOD testing a water sample, using the bottle described above with reference to Figures 1 to 9, will now be described. The bottle 1 is first filled up with a water sample. The bottle 1 is filled up to the mouth 5 (i.e. the top of the neck portion 7). Next, a probe (not shown) is inserted into the bottle through the mouth 5. The probe is used to stir the water sample, and takes a reading of the oxygen content of the water. The elongate neck portion 7 is so shaped that bubbles formation in the bottle is reduced.

Once the data has been obtained, the probe is removed and the bottle 1 must be sealed to prevent any oxygen entering or leaving the bottle (which would affect the BOD test). To seal the bottle, the stopper 15 is firmly screwed onto the bottle until an annular seal is formed between the stopper and the bottle. The act of inserting the probe tends to displace a small volume of water from the bottle. However, the fluid displacing element 23 of the stopper is sufficiently large to

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-17 -displace any air, and a small amount of the sample at the top of the neck portion. Thus, the risk of any air bubbles being trapped in the bottle is reduced.

Whilst the present invention has been described and illustrated with reference to a particular embodiment, it will be appreciated by those of ordinary skill in the art that the invention lends itself to many different variations not specifically illustrated herein. Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims.

Claims

-18 -Claims 1. A Biochemical Oxygen Demand (BOD) testing bottle, the bottle comprising a mouth and the bottle having a stopper located in the mouth for inhibiting fluid communication into and out of the bottle through the mouth, wherein the stopper comprises a fluid displacing element, arranged to displace fluid in the bottle in the region of the mouth, and wherein the bottle and stopper comprise complementary screw threads for holding the stopper in the mouth so as to form a seal between the stopper and the bottle.
2. A BOD testing bottle according to claim 1, wherein the bottle is made of plastics material.
3. A BOD testing bottle according to claim 1 or claim 2, wherein the stopper is made of plastics material.
4. A BOD testing bottle according to claim 2 or claim 3 wherein the plastics material itself is substantially oxygen-impermeable.
5. A BOD testing bottle according to any preceding claim, wherein the bottle comprises a voluminous main body portion and an elongate neck portion connecting the main body portion with the mouth.
6. A BOD testing bottle according to claim 5, wherein the elongate neck portion has a height of between 35.0mm and 45. 0mm.

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7. A BOD testing bottle according to any preceding claim, wherein the screw thread on the stopper comprises a plurality of substantially planar ridges.
8. A BOD testing bottle according to any preceding claim, wherein the fluid displacing element on the stopper extends below the screw thread on the stopper.
9. A BOD testing bottle according to any preceding claim, wherein the stopper comprises a marker element for indicating the particular use and/or contents, of the bottle.
10. A stopper for use as the stopper in the BOD testing bottle according to any of claims 1 to 9, the stopper comprising a fluid displacing element for displacing fluid in the bottle in the region of the mouth and a threaded portion for engagement with a complementary thread on the bottle.
11. A BOD testing bottle, the bottle comprising a mouth and the bottle having a stopper located in the mouth for inhibiting fluid communication into and out of the bottle through the mouth, wherein the stopper comprises a fluid displacing element arranged to displace fluid in the bottle in the region of the mouth, and wherein the bottle comprises a voluminous main body portion and an elongate neck portion connecting the main body portion with the mouth, the elongate neck portion being so shaped to inhibit bubble formation in the neck portion, when a probe is inserted into, and agitates, a sample in the bottle.

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12. A BOD testing bottle according to claim 11, wherein the elongate neck portion has a height of between 35.0mm and 45. 0mm.
13. A BOD testing bottle according to claim 11 or claim 12 wherein the elongate neck portion is in the form of a generally circular cylinder having an outside diameter of between 34.0mm and 38.0mm.
14. A BOD testing bottle according to any of claims 11 to 13, wherein the ratio of the height of the elongate neck portion to the height of the bottle is between 2.50:1 and 3.50:1.
15. A BOD testing bottle according to any of claims 11 to 14, wherein the main body portion comprises a circular cylindrical region and a tapered region, the tapered region joining the circular cylindrical region to the neck portion.
16. A BOD testing bottle according to claim 15, wherein the circular cylindrical region of the main body portion has an outside diameter around 71mm.
17. A BOD testing bottle according to any of claims 11 to 16, wherein the height of the main body portion is between 75.0mm and 85.0mm.
18. A method of obtaining a sample for Biochemical Oxygen Demand (BOD) testing, comprising the steps of: filling a bottle with the sample to be tested, placing a stopper in the mouth of the bottle, the stopper comprising a fluid displacing element for displacing fluid in the mouth of the bottle, and -21 -twisting the stopper relative to the bottle to engage complementary screw threads on the bottle and the stopper so as to draw the bottle and the stopper together, forming a seal between the stopper and the bottle.
19. A method according to claim 18, wherein the bottle and the stopper are the bottle and stopper according to any of claims 1 to 9.
20. A method of obtaining data in a Biochemical Oxygen Demand (BOD) test, the method comprising the steps of: filling a bottle with a sample to be tested, the bottle comprising an elongate neck portion, inserting a probe into the elongate neck portion of the bottle to measure the oxygen content of the sample, the elongate neck being so shaped to inhibit bubble formation in the neck portion upon stirring of the probe.
21. A method of BOD testing according to claim 20, wherein the bottle is the bottle according to any of claims 11 to 17.
22. A bottle and/or stopper as shown in, and described with reference to, the accompanying drawings.