GB2236522A

GB2236522A - Total immersion liquid sampling

Info

Publication number: GB2236522A
Application number: GB9021553A
Authority: GB
Inventors: Riginos Kimonides
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-10-07
Filing date: 1990-10-04
Publication date: 1991-04-10
Also published as: GB9021553D0; GB8922623D0

Abstract

A method and apparatus for sampling liquids at any selected depth in, for example, a storage tank, comprises a valve assembly mounted at one end of a sampling bottle 12. An inlet valve 36 is held firmly closed during descent into the liquid to be sampled. A jerk on the supporting tension member 18 opens the inlet valve. When the vessel is full of liquid to be sampled, a floating ball valve 22 seals the inlet while the apparatus is raised. The sampling vessel can then be detached from the valve assembly and hermetically sealed immediately without pouring or other contamination, by application of a screw cap. Spring-loaded balls in detents 42 and compression spring 38 co-operate to keep valve member 36 closed until line 18 is jerked. <IMAGE>

Description

METHOD AND APPARATUS FOR LIQUID SAMPLING This invention relates to a method and apparatus for liquid sampling. An example of the application of the invention is to the sampling of all kinds of liquid in storage tanks, and in the tanks of ocean-going oil tankers and the like. In my prior British patent GB2 170 477B and its corresponding US specification US4 790 197, I have described and claimed liquid sampling apparatus to provide a means for sampling liquids acurately and precisely at the bottom of storage tanks and the like. That apparatus includes facilities for sampling also at pre-determined depths slightly above the bottom of such tanks.

However, there is a requirement for a method and apparatus for sampling which enables a sample to be taken at any depth within a body of liquid, and thus some means is needed to enable actuation of suitable valves associated with a sampling chamber to admit liquid to the chamber when the latter is at precisely the required depth, and then subsequently to seal-off the chamber to prevent subsequent contamination.

Various prior proposals have been made to meet this requirement. These include the well-known simple sampling can, in which a can, which is sufficiently heavy to sink, is supported on a piece of string and provided with a cork to seal the open end of the can. The assembly is lowered into the liquid with the cork in place in the neck of the can, and with the string lodged between the cork and the can neck so that when the assembly reaches a required depth, a jerk by the user dislodges the cork and allows liquid to enter.

The above apparatus is simple and relatively easily used, but suffers from the defects that liquid is able to enter the can as it sinks, around the cork due to the imperfect seal caused by the presence of the string.

Also, the can neck remains entirely open when the can is subsequently raised, and thus at least the upper level of the liquid is contaminated by liquid from other depths.

Proposals have been made also for more sophisticated apparatus. These have included special sampling vessels having integral inlet and outlets valves at opposite ends of the vessel to perform their appropriate functions.

However, these latter proposals are for relatively complex and correspondingly expensive items of apparatus in which valve-actuating shafts and associated equipment run lengthwise of the sampling vessel. As a result, there is considerable difficulty in satisfactorily cleaning and in some cases sterilising the apparatus between successive sampling operations. Also, it is necessary to pour the sampled liquid from the sampling vessel into some other container for analysis. This latter step leads to aircontamination which is unacceptable for certain liquids, particularly volatile petrolum products.

Accordingly, I have identified a requirement for an improved method and apparatus for liquid sampling in which the basic advantages of the simple sampling can are largely retained, while its disadvantages in terms of contamination and inaccuracy are reduced, and an object of the present invention is to provide a method and apparatus offering improvements in one or more of these respects, or generally.

According to the invention there is provided a method and apparatus for liquid sampling as defined in the accompanying claims.

In a preferred embodiment, sampling apparatus comprises various forms of sampling chamber having an outwardly - opening valve. The valve is spring-loaded and arranged to be actuated by a line attached to the device so as to permit sampling at any desired depth.

The apparatus is applicable not only to oil tankers, shore tanks and underground storage facilities, but also to other liquid sampling environments, including vats generally, the sea, rivers and other waterways, reservoirs wells and analogus applications.

The prefered embodiments, described below with reference to the drawings, avoid the disadvantage of the simple sampling can with regard to contamination by fallout from the sounding pipe (through which the sampling apparatus is lowered) and from the supporting line or cord.

Due to the open neck of the can after sampling, and while the can is raised, the liquid is very susceptible to contamination.

The described embodiments also minimise the risk of contamination by providing that the sampling vessel is sealed-off from the surrounding liquid both during descent and subsequent ascent. Moreover, the high accessibility provided by the disengageable valve assembly enables temperature observation of the sampled liquid to be readily obtained. Likewise, if decanting of the liquid is needed, this is readily achieved and the apparatus is easy to clean.

In the preferred embodiment, the liquid sampling apparatus has a sealable vessel defining a sampling chamber to receive and temporarily or permanently store a liquid to be sampled. A port in the sampling vessel permits escape of air and entery of liquid. A valve mounted at the port controls the passage of fluids through the port. The valve moves outwards and inwards to open and close the valve, respectively. The valve is actuable by a cord or tape. An upward jerking action is able to pull the valve member upwards from its closed position. The provision of an outwardly opening valve member reduces the need for substantial chamber weight. Therefore, the weight of the apparatus is relatively low while still being heavy enough to sink. Part of the valve assembly acts as a shield or "umbrella" for the mouth of the sampling vessel, to protect same during the sampling process.

The jerk-open action of the inlet valve enables sampling to commence at any desired level in the liquid and the provision of a floatable valve member associated with the sampling chamber enables the sampled liquid to be sealed-off from contamination.

In the preferred embodiments, the feature of the disengageability of the valve means can be achieved in two main ways. Either the sampling vessel can itself be detached or disconnected from the valve assembly eg by unscrewing the vessel. Alternatively, the sampling vessel, or bottle, can be allowed to remain connected to the valve assembly, but the latter, or at least a portion of the valve assembly, can be disengaged from the sampling vessel by, for example, moving it to one side from its sampling position. This latter arrangement is of particular merit where, for example, a metallic sampling vessel is employed, and accordingly the valve means is constructed so as to be permanently attached to the vessel.In the preferred embodiments, the feature of the disengageability of the valve means from the sampling vessel produces the advantages that, where it is desired to have the minimum of disturbance and contamination of the sampled liquid, then the sampling vessel can be immediately disconnected and sealed after sampling. Alternatively, where it is wished to decant the sampled liquid immediately after sampling, all that is needed to effect this is simply to swing the valve assembly, or part of it, to one side for this purpose.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: Figs 1 and 2 show longitudinal sectional views through a first embodiment of the invention with an inlet valve in its closed and open positions, respectively; Fig 3 shows an exploded view of the apparatus of Figs 1 and 2; Fig 4 shows an exploded view of a valve member of the apparatus of Fig 3; Fig 5 shows an exploded view of a mounting for the valve member of Fig 4; Fig 6 shows, in a view similar to those of Figs 1 and 2, a second and simplified embodiment of the invention.

As shown in Figs 1 to 5 of the drawings, apparatus 10 for sampling a liquid comprises a sampling vessel 12 having an inlet 14 with valve means 16 therefor which can be opened by means (for example jerking) a supporting tension member 18 connected to the valve member.

In use, the apparatus is allowed to sink in a liquid to be sampled, simply by lowering it on tension member 18, with the valve mean 16 closed, the overall weight of the apparatus in the liquid concerned being sufficient to cause it to sink. Then, the valve means 16 is opened when the apparatus reaches a chosen depth, to admit liquid to be sampled. Subsequently, the apparatus is raised with the sampled liquid within the sampling vessel.

Valve means 16 is in the form of an assembly which is mounted at one end of the sampling vessel 12, and is disengageable from the sampling vessel, after sampling, to enable either closure of the vessel for storage, or removal of the liquid for analysis. In both cases the disengagement of the valve means has the result that the valve means does not interfere with these operations.

Although not indicated as such in the drawings, it will be understood that a simple sealable cap could be very readily provided for the vessel in the form for example of a plastic screw threaded cap.

Valve means 16 has provision for the inlet to the sampling vessel 12 to be subseqently closed after admission of the sample, and before raising of the apparatus from the sampling depth. For this purpose, there is provided a closure valve of the float type having a buoyant valve member in the form of a ball 22 adapted to co-operate with and seal against an annular valve seat 24. Ball 22 is lifted into sealing engagement with seat 24 when the inflowing liquid to be sampled has filled vessel 12 and valve means 16.

In this embodiment, sampling vessel 12 is in the form of a bottle 26 having an external screw thread 28 on its neck 30, to co-operate with a complementary thread formed inside a housing 32 of valve means 16. Housing 32 houses the valve ball 22 and provides valve seat 24.

Also forming part of valve means 16 is an inlet valve 34 which is located outside housing 32. The inlet valve comprises a two-position valve member 36 which can be jerked from a closed position shown in Fig 1 to an open position shown in Fig 2, and which has resilent means in the form of a spring 38 biasing the valve member towards its closed position to assist sealing.

The two positions of the valve member are defined by a spring-loaded detent 40 co-operating with spaced groove means 42, 44 on a slideable valve guide member 46.

A mounting 48 for guide member 46 provides a screen or cover to protect the inlet 14 of sampling vessel 12 after raising the latter from a liquid to be sampled.

Turning now to further details of the apparatus 10, the mounting 48 for valve guide member or stem 46 is in the form of a cover plate or "top hat", which, as shown in Fig 3 is in the form of a disk 50 formed with a central bore to receive the valve stem 46. Disk 50 has two radial drillings 52 having internal screw threads at their outer ends and receiving the detents 40 which are in the form of ball bearings 54 biased inwardly by springs 56 located by grub screws 58.

The underside of disk 50 is formed with two threaded drillings to receive and engage a pair of support rods 60 which engage and support at their other end, housing 32.

As regards inlet valve 34, the valve guide member 46 has a bore 62 formed at one end to receive the stem 64 of valve member 36 as a sliding fit therein and spring - urged outwardly by a coil spring 66. Valve member 36 is retained by a retaining bolt 68 received in an aperture 70 in valve stem 46 and extending through a slot 72 in stem 64, the slot thus defining the necessary lost motion for valve movement.

Valve guide member or stem 46 is slidingly received in the central aperture in disk 50, and groove 42 receives ball bearings 54 to define the valve - closed position. An aperture 74 is provided to receive tension member 18, in the form of a cord.

Housing 32 comprises upper and lower portions 76, 78 respectively which are securable together by bolts 80, in sealing engagement by virtue of an 0-ring 82. A corresponding o-ring 84 is provided to seal between housing lower portion 78 and bottle 26. Upper portion 76 of housing 32 provides valve seat 24 which includes a flat upper valve seating surface 86 for engagement with valve member 36, and a frusto-connicle seating surface 88 formed internally for sealing engagement with the valve ball 22.

The ball is located by means of a radial retaining member.

90 mounted on lower housing portion 78.

A stand and guard member 92 is fixed to housing 32 and extends lenghtwise of bottle 26 and has a lower, generally circular, stand portion 94 located below bottle 26 to protect same when the apparatus descends rapidly in use.

The stand also assists in providing the necessary degree of negative buoyancy for the apparatus.

In use, the apparatus is assembled as shown in Fig 1 and lowered into the liquid to be sampled with the inlet valve 34 closed. When the required depth is reached, the user jerks tension member 18 and this is sufficient to allow valve guide member 46 to disengage from detent 40 and move to its Fig 2 position opening the valve.

Liquid to sampled rapidly enters bottle 26 through housing 32, and the air within the sampling vessel correspondingly escapes. When the liquid level rises to the top, ball valve 22 closes and the apparatus can then be raised without risk of contamination of the sampled liquid.

As the apparatus is raised, top hat 48 protects the sampling vessel 12 from contamination which might otherwise fall onto the mouth of the vessel. Bottle 26 can be readily unscrewed as soon as it has reached the user. It can be sealed with a suitable cap screw threaded onto its neck, or (when appropiate) the contents can be tipped into a further container for analysis purposes.

Interestingly, the above embodiment provides sampling apparatus in which the advantages of a detachable and sealable sampling vessel are combined with those of valve sealed avoidance of contamination during both descent and ascent of the apparatus to and from the sampling depth.

All this is achieved in a simple structure, and in a cost effective manner. A series of sampling containers, such as bottles, can be used with a single set of valve apparatus.

By the provision of an outwardly - opening inlet valve member, the need for substantial chamber weights is avoided.

In the apparatus 100 in Fig 6, the structure and arrangement is otherwise as described above except that the sampling vessel 102 is formed with the valve means 104 connected to it by link members 106 whereby the valve means can be either held in the valve - engaged condition shown in Fig 6, or, by jerk actuation of the tension member 18, the valve can be opened to permit vessel 102 to be filled.

The valve 104 then remains open while the apparatus is raised for sampling. In this embodiment no ball valve is provided as part of valve means 104. This simplifies the structure. In this embodiment, the valve means 104 is simply disengaged from the in-use position shown in Fig 6, in order to enable the sampled liquid to be removed, for example by tipping from the vessel 102.

In this embodiment, the structure and arrangement of the valve means 104 is exactly as described above, except for the absence of the ball valve, and some corresponding modifications to the proportions of the valve seat 108 provided for engagement with valve member 110.

In this embodiment, the valve assembly is simply disengaged and pushed to one side when it is desired to discharge the sampled liquid. Otherwise, this embodiment is used in exactly the same manner as that of Figs 1 to 5.

In a further embodiment, modifications are introduced into the embodiment of Figs 1 to 4. Firstly, a pivot connection is provided between the support rods 60 and the upper portion 76 of housing 32, whereby the rods 60 and the structure which they support can be pivoted or swung to either side about a pivot axis 120. This renders the operation of decanting liquid from bottle 26 a simpler operation.

Also, there is provided along the length of the longitudinal portion of stand and guard member 92, a slidable locking sleeve 122 (shown in dotted lines) which is spring-biased to its locking position, but which can be readily moved lengthwise of member 92, to permit the lower portion 124 thereof to be swung to the side about an axis 126. This simplifies removal of bottle 26.

A further feature concerns the diameter of the valve seat and opening as shown at 128 in Fig 2. Tests have shown that, where a relatively light liquid such as petroleum is being sampled, there is a tendency for the ball valve member 22 to seal prematurely on the seat 86.

Tests have shown that this tendency can be eliminated by modification of the diameter of the opening 128. Thus, for a ball diameter of 25mm, a reduction of the seat opening diameter from 24mm to 22mm entirely eliminated this problem.

Claims

1 A method of sampling a liquid comprising: a) providing a sampling vessel having an inlet with valve means therefor which can be opened by means (eg jerking) of a supporting tension member; b) the method further comprising the step of causing the sampling vessel to sink in a liquid to be sampled; c) opening said valve means at a chosen depth to admit liquid to be sampled; d) raising the sampling vessel with the sampled liquid therein; characterised in that e) said valve means is in the form of an assembly which, in use, is mounted at one end only of said sampling vessel, and is disengageable therefrom after sampling, and the method further comprising the step of disengaging said valve means from its sampling position with respect to said sampling vessel, to enable closure of the vessel for storage or removal of liquid therefrom.

2 A method according to claim 1 characterised by the step of disengaging said valve means by disconnecting (eg by unscrewing) said sampling vessel from said valve assembly.

3 A method according to claim 1 or claim 2 characterised by the step of disengaging said valve means by moving at least part of said valve means to one side with respect to its sampling position, while said valve means still remains attached to said sampling vessel, whereby sampled liquid can be decanted therefrom.

4 A method according to any one of the preceding claims characterised by the step of applying closure means to said inlet of said sampling vessel to close same for storage purposes without the need to remove liquid therefrom.

5 A method according to any one of the preceding claims characterised in that said valve means can be subsequently closed after admission of a liquid to be sampled, the method comprising the step of closing said valve means prior to raising the sampling vessel from the sampling depth.

6 A method according to claim 5 characterised in that said valve mean comprises a float type valve to effect closure of the valve means after admission of liquid, and the method comprising the step of causing the sampled liquid itself to effect such closure.

7 A method of sampling a liquid substantially as described herein with reference to the accompanying drawings.

8 Apparatus for sampling a liquid comprising: a) a sampling vessel having an inlet for liquid to be sampled with associated valve means therefor, which valve means can be opened by means (eg jerking) of a tension member; b) the sampling vessel being adapted to sink in a liquid to be sampled; c) said valve means being actuable to open the valve at a chosen depth to admit liquid to be sampled; d) a tension member being provided to enable the sampling vessel to be raised with the sampled liquid therein; characterised in that e) said valve means being in the form of an assembly which, in use, is mounted at one end of said sampling vessel and is disengageable therefrom after sampling, to enable closure of the vessel for storage of the sample of liquid, or removal of the liquid therefrom.

9 Apparatus according to claim 8 characterised by said valve means being disengageable from said sampling vessel by disconnecting (eg by unscrewing) said sampling vessel from said valve assembly.

10 Apparatus according to claim 8 or claim 9 characterised by said valve means being disengageable from said sampling vessel by moving at least part of said valve means to one side with respect to its sampling position while still remaining attached to said vessel, whereby sampled liquid can be decanted.

11 Apparatus according to any one of claims 8 - 10 characterised by further closure means, for example a closure cap, for said inlet of the sampling vessel, to close same for storage purposes without the need to remove liquid therefrom.

12 Apparatus according-to any one of claims 8 - 11 characterised in that said valve means comprises a valve member which can be closed after admission of said liquid to be sampled.

13 Apparatus according to any one of claims 8 - 12 characterised in that said sampling vessel is in the form of a bottle or other vessel which is detachable from said valve means.

14 Apparatus according to any one of claims 8 - 13 characterised in that said valve means comprises a housing for a closure valve to close said inlet after admission of a liquid to be sampled, and said inlet valve is located outside said housing.

15 Apparatus according to claim 14 characterised in that said valve comprises a floatable valve member.

16 Apparatus according to claim 15 characterised in that said floatable valve member is in the form of a ball.

17 Apparatus according to any one of claims 14 - 16 characterised in that said inlet valve comprises a twoposition valve member which can be jerked, by means of a tension member, from a closed position to an open position, the valve member having resilient means adapted to bias the valve member towards its closed position to assist sealing in that position.

18 Apparatus according to claim 17 characterised in that the closed position of said valve member is defined by spring-loaded detents co-operating with groove means on a slideable valve guide member.

19 Apparatus according to any one of claims 14 - 18 characterised by a mounting for said inlet valve which provides a screen or cover to protect the inlet of said sampling vessel after raising of the apparatus from a liquid to be sampled.

20 Apparatus for sampling a liquid substantially as described herein with refernce to the accompanying drawings.