Abstract:
Liquid sampling apparatus for sampling liquid at a controlled depth within the tanks of an ocean going oil tanker comprises a sampling chamber having outwardly opening inlet and outlet valves. The inlet valve 114 is arranged to be actuated by a projecting valve actuator 132 through a lever mechanism and is adjustable by means of a spring clip 136 so as to permit sampling at varying distances from the bottom of the tank. The outlet valve is a pressure-relieving ball valve 138 permitting automatic escape of air during filling of the sampling chamber, but preventing entry of liquid. The apparatus is lowered in use through an MMC stand on a wire carried by a support 140 at the top of the apparatus.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to liquid sampling apparatus. There is disclosed below such apparatus for obtaining samples of water from a mixture of oil and water contained in oil tanks, especially the tanks of ocean going oil tankers, corresponding shore tanks, and underground fuel storage tanks, where access to the base of the tank is difficult to obtain. The invention is also applicable to other liquid sampling environments, including sampling from storage tanks and vats generally, the sea bed, rivers and other waterways, reservoirs and wells, and analogous applications. 
     There is a need to obtain water samples from the water which is often found to be mixed with the oil in the tanks of oil tankers. Such water samples are used for analysis purposes. The analysis enables data to be obtained which may permit identification of the source of the water. 
     There is disclosed in U.S. Pat. No. 3,680,389 (Binkley) sampling apparatus for a waste disposal system, particularly for use at an off-shore location. A sampling vessel has upper and lower valves actuated by a projecting foot. The foot is connected by an actuating rod 43 to the two valves to actuate same, and thus they both open upwards. Coiled compression springs 56,57 hold the valves in their closed position. An annulus 33 is provided to house heavy ballast material whereby the weight of the apparatus can be sufficient to enable the valves to be opened through the medium of foot 58 and rod 43. 
     There is a need for improvements with respect to the above-mentioned prior art in several respects. Firstly, there is a requirement for sampling apparatus which is smaller and lighter in weight and thus easier to handle than the prior art. In particular, it would be beneficial if the need for ballast weight could be avoided. Secondly, with regard to the application of the sampling apparatus to situations in which it is desired to sample liquid at a well defined depth, and perhaps varying depths, close to but not necessarily at the bottom of an oil tank, or on the sea bed, there is a need for means whereby this can be achieved. Other desirable refinements relate to the general construction of such a device, its economy of manufacture and ease of use. 
     Accordingly, a general aim of the invention is to provide liquid sampling apparatus having improved means for operating the valves thereof, particularly means whereby the load required to open the valves is reduced. 
     Another aim of the invention is to provide liquid sampling apparatus having means whereby the depth at which the valves are opened, can be adjusted. 
     Still another aim of the invention is to provide liquid sampling apparatus which can be made in a form which is lighter in weight, less bulky, and more readily utilised. 
     SUMMARY OF THE INVENTION 
     The present invention resides in liquid sampling apparatus having a sealable sampling vessel defining a chamber to receive and temporarily store a liquid to be sampled. Upper and lower ports are formed in the sampling vessel to permit escape of air and entry of liquid to be sampled, during the sampling process. Upper and lower valve means are mounted at the ports to control the passage of fluids through the ports. According to one feature of the invention, both the upper and lower valve means comprise valve members mounted for movement outwards and inwards with respect to the sampling vessel, respectively to open and close the valves. 
     In accordance with another feature of the invention, the lower valve means is actuatable by a projecting actuator member which is engageable with a bottom surface of a liquid tank or the like being sampled. The actuator member is connected to the valve member by a lever mechanism whereby inward movement of the actuator member causes outward movement of the valve member. 
     In the embodiments, by the provision of outwardly opening valve members, the need for substantial valve closure springs is avoided. The liquid pressure itself tends to hold the valves shut. Therefore, a relatively small actuating thrust is capable of opening at least the lower liquid inlet valve. In this way, the weight of the apparatus when constructed from conventional materials is usually sufficient for the purpose. 
     In the embodiment also, the upper valve means, for air escape, is constructed as a ball valve which opens as a result of increasing air pressure within the chamber. In this way, the need for direct actuation of the upper valve is avoided. 
     A further feature of the embodiment lies in the provision of adjustable connecting means between an extensible actuator projecting from the base of the apparatus, and the valve operating mechanism, whereby the apparatus can be set to commence sampling at varying distances from the bottom of an oil tank or the like. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     FIGS. 1, 2, 2A, 3, and 4 show in generally exploded form, liquid sampling apparatus according to the invention; 
     FIGS. 5 and 6 show sectional views through the assembled apparatus of FIGS. 1 to 4 in its valve-closed and valve-open configurations; and 
     FIGS. 7 to 13 show a second embodiment, the views corresponding, generally speaking, to those of FIGS. 1 to 6; 
     FIG. 7 shows an exploded view of the apparatus corresponding to FIG. 1; 
     FIG. 8 shows a scrap sectional view showing details of an inlet valve arrangement; 
     FIG. 9 shows a valve actuating rod; 
     FIG. 10 shows a scrap sectional view of an outlet valve assembly; 
     FIG. 11 shows a detail of a finger-actuated adjustment mechanism for the rod of FIG. 9; 
     FIGS. 12 and 13 show the assembly of FIG. 7 with the inlet valve in its closed and open positions respectively. 
    
    
     DETAILED DESCRIPTION 
     As shown in the drawings, liquid sampling apparatus 100 comprises a sealable sampling vessel having a main tube 102 with a top cap 104 and a bottom cap 106, the latter being formed with radial drillings 108 forming screening inlet openings leading to the interior of tube 102. A collar 110 fits within tube 102 and seats against an internal shoulder 112 formed therein. Between collar 110 and top cap 104 there is defined a chamber to receive and temporarily store a liquid to be sampled. 
     A lower valve assembly 114 controls the inlet of liquid from openings 108 through a port in collar 110 into the sampling chamber 116 above the collar. 
     Lower valve assembly 114 comprises a sliding valve member 118 adapted to seat against a conical valve seat 120 formed in collar 110 and biased by a valve spring 122, to its closed condition shown in FIG. 5. The lower end of valve member 118 is actuated by a lever-type valve actuating arm 124 which is pivotally mounted on a central valve actuating assembly 126 slidably mounted in a guide tube 128 within main tube 102. 
     The valve actuating assembly includes a central rod 130 having a base plate 132 and formed with apertures 134 whereby the rod is adjustably connected by means of a spring clip 136 to a tube 138. In this way, base plate 132 is mounted at an adjustable distance from the valve actuating lever 124 for a purpose to be described. 
     At the top of the apparatus a ball-type non-return valve 138 operates as a pressure-relief valve, permitting air to escape during sampling through a port formed in top cap 104, but preventing water (or other liquids) entering. 
     The drawings also show O-rings and other sealing members forming part of the apparatus, as will be appreciated by those skilled in the art. 
     In use, base plate 132 is set at the desired distance below bottom cap 106 so as to cause inlet apertures 108 to sample the liquid at the desired height above the base of the tank. The apparatus is lowered into the liquid to be sampled with the main tube 102 full of air. The weight of the apparatus causes same to descend through the liquid. Ball valve 138 prevents the entry of liquid. At this stage, valve spring 122 is holding lower valve 114 in its closed condition. When the apparatus reaches the base of the tank, or the sea bed, the weight of the apparatus causes an upthrust to be applied to the valve actuating members thereby pivoting lever 124 and causing valve 114 to open, as shown in FIG. 6, this permits liquid to enter tube 102. The rise in air pressure unseats ball valve 138 and allows the air in the chamber to escape. After a certain time interval the chamber is full and the apparatus can be raised on the lift gear 140. 
     It will be noted that an end tube 142 in top cap 104 receives guide tube 128, thereby supporting same against bending stress during use. 
     Further features to which attention is directed in the embodiment include the relatively small diameter of the liquid entry valve 114 as compared with the diameter of the chamber 116, whereby the thrust due to liquid pressure at the sampling depth, exerted on valve member 118 is proportionately reduced, so that spring 122 can be correspondingly light in action. Preferably, the external diameter of the valve member 118 is less than half the diameter of the chamber, and preferably about a quarter, or less. 
     In the embodiment, main tube 102 is formed of brass and thus has fully adequate weight to actuate valve 114 at all normal operating depths of the apparatus. 
     The moving parts of the apparatus are preferably manufactured of stainless steel. The inlet drillings 108 act as a screen or filter device. In use, a period of the order of sixty seconds may be required to allow the apparatus to fill with the liquid being sampled. During this period, air within the apparatus escapes through valve 138. This latter valve permits easy emptying of the liquid sample after use. For this latter purpose, valve 114 should preferably be manually held in its open position by pushing inwards on foot 132. 
     In the embodiment, the above-described valve arrangements avoid the disadvantages of certain prior art apparatus that there was a tendency for liquid to enter the sampling chamber before the required sampling depth had been attained, thereby negating the entire purpose of the sampling exercise. 
     In the embodiment shown in the drawings the maximum variation in sampling depth corresponds, more or less, to the axial length of the apparatus. However, by means of a simple modification, the projecting actuator member could be arranged to be capable of projecting right through the apparatus at both ends, whereby much greater variation in sampling depth could be achieved. By defining the sampling depth with reference to the bottom of the tank, or the sea bed, rather than by measurement from the suspension wire, significantly greater accuracy can be achieved. Moreover, by sampling with liquid inlets to the apparatus at the defined sampling height, the disadvantages of prior apparatus in which the liquid inlet is positioned at the bottom of the apparatus and thereby tends to become blocked with sludge, are avoided. The diameter of the liquid inlet drillings is relatively small so that liquid is sampled at a precisely defined level. The range of inlet aperture widths or diameters may be from 3.0 to 10.0 millimetres, depending on the liquid viscosity. 
     The inlet valve of the sampling apparatus could be actuated by tension means, for example a wire, cable or the like. Preferably, the arrangement would be such that actuation and support for the apparatus would be effected by a single wire or the like. 
     In the embodiment, the small overall diameter of the sampling apparatus permits it to be inserted through and used via an MMC stand having a top inlet diameter of 43 millimeters. Previously proposed apparatus is incapable of operating through the small inlet opening of the MMC stand&#39;s vapour lock O-ring. 
     In a further modification of the described embodiment, apertures are provided in the bottom plate or foot of the valve actuating member 132, so as to reduce the upthrust of the liquid thereon during descent through the liquid, in a tank being sampled. In this modification, and indeed in the described embodiment, the plate is able to retract right up against the bottom of the apparatus so as to permit liquid sampling very close to or at the bottom of the tank in certain conditions where this is desirable. 
     FIGS. 7 to 13 show a second embodiment of the invention. In this embodiment, parts corresponding to those in FIGS. 1 to 6 are given the same reference numerals and, in general, require no further discussion. 
     Attention is directed particularly to the structure and arrangement of the inlet valve assembly 200 which controls the inlet of fluid to sampling chamber 116 through a port 201. The valve member 118 itself is mounted on a rod or stem 202 actuated by a coiled compression spring 122, as in the previous embodiment. The conical valve member is adapted to seal against a seat 204 formed in an inlet member 206. Inlet member 206 has threaded portions 208 and 210 whereby it is screw-threadedly secured to main tube 102 and to a collar 212 respectively--these latter two components being formed with internal screw threads for the purpose. O-rings 214,216 seal the inlet member 206 to tube 102 and collar 212. O-ring 216 avoids the escape of air trapped in collar 212 during descent of the apparatus into a tank or the like, thereby ensuring that the entry of liquid into collar 212 as the apparatus descends through a body of liquid during use, is minimised until the valve assembly is opened, under operator control. 
     In this embodiment, the tube 128 mounted within main tube 102 forms a zone open at its outer end to the external body of liquid to be sampled, and which is sealed to member 206 against the escape into it of fluid within the sampling chamber 116. Valve actuating member 132 is telescopically received in tube 128 in an adjustable manner as described below. The top end of tube 128 is located in a recess formed in top cap 104, quite close to the port therein controlled by ball valve 138. 
     For actuating valve 118 there is provided an actuating mechanism 218 comprising an actuating block 220, a lever 222 and a pivot pin 224. Actuating block 220 is position-adjustably connectible to rod 130 in a manner to be described. Lever 222 is connected to block 220 by means of a pin projecting from the block and received in an elongated slot 226 at one end of the lever. At its other end, lever 222 is pivotally connected to a rod 228 projecting from valve member 118. Intermediate its ends, lever 222 is formed with a recess 230 to receive pin 224. It will now be seen that inward (upward as seen in FIG. 7) movement of rod 130 with respect to tube 102 causes clockwise angular movement of lever 222 about the end of pin 224, between the positions shown in FIGS. 12 and 13. This causes valve 118,204 to be opened. 
     FIG. 11 shows a finger-actuated adjustor mechanism for connecting block 220 to rod 130. A slidable U-shaped detent 232 is urged by a spring 234 to the position shown in FIG. 11. The user can adjust block 220 with respect to rod 130 by pressing on the end 236 of detent 232 so as to disengage the other end of the detent from the relevant hole 134 in rod 130. The detent can then be re-engaged with the rod at a new chosen position. 
     Attention is also directed to the holes or apertures 238 in base plate 132 for reducing upthrust during descent through a liquid. Note also that collar 212 is open at its lower end, whereby there is free access of liquid to valve mechanism 118,204. The collar serves to protect the valve actuating mechanism 218. For thick liquids, or other liquids not requiring screening, this arrangement provides improved access to the apparatus. The fill time for the apparatus may be reduced to about ten seconds. 
     In use, the apparatus functions very much as described above for the first embodiment. The valve actuating arrangements and the relatively small diameter of the valve 118 (0.5 to 1.0 centimeters) ensures easy opening of the valve when base plate 132 reaches the bottom. There is no need to bump the apparatus on the bottom. The valve spring and actuation mechanism is such that the valve opens under a weight of approximately one kilogram in air. The total weight of the apparatus when containing air only, is approximately two kilograms in water. The apparatus can be used at depths of the order of 100 meters, or indeed any depth such that the operator is able to sense and control the step of causing the apparatus to reach the bottom and to open its valve under its own weight. 
     In this embodiment, the simple mechanical actuation of the valves ensures complete safety for use, for example, in sampling highly volatile fuels. The valve and sealing arrangements maximise the sampling efficiency and accuracy. The independent actuation of the valves permits efficient valve actuation without the precision hitherto required by prior art apparatus employing linked valves. The outward opening of the valve members ensures efficient sealing during descent.