Abstract:
A fluid sampling device is provided that can obtain both point and integrated samples of a body of fluid at various depths. The device includes an easy to use and reliable closure mechanism that does not rely on a traditional messenger mechanism.

Description:
FIELD OF THE INVENTION 
   My invention relates to an apparatus and method for sampling fluids. More specifically, the invention relates to an apparatus that can collect fluids at a single depth or across a range of depths for subsequent analysis. 
   BACKGROUND OF THE INVENTION 
   Fluid sampling devices, especially those used to collect aqueous samples from large bodies of fluids, for example, oceans and lakes, are well known. Such devices can be used to collect surface or near-surface physical, chemical, or biological (phytoplankton/zooplankton) samples in natural water bodies or industrial or man-made facilities (waste water ponds, water treatment plants, food processing plants, oxidation ponds, etc.) In particular, collection of water samples below the surface provides scientists the ability to obtain a sample at a known depth, retrieve the sample, and then perform analysis on the sample at a later point in time. By collecting a number of samples at various depths, a profile analysis of the body of fluid can be obtained. Unfortunately, existing sampling devices are cumbersome to use because their spring loaded closure designs require the use of a weighted messenger that must travel down a connecting line through the fluid and then trip a trigger that activates the closing mechanism. Such designs are known to frequently malfunction causing the device to close prematurely or to not close at all. Examples of these designs include three well known sampling bottles marketed under the names “Van Dorn,” “Niskin,” and “Kemmerer.” Each of these designs relies on a spring-loaded cover or cap that must be triggered when the device is lowered to a specified depth. Another serious drawback of these known sampling bottles is that they can only obtain one kind of sample, either “point” samples, i.e., obtain only a single sample at a single depth when in horizontal position (e.g. “Van Dorn”), or “vertically integrated” samples when in the vertical position A need therefore exists for a reliable, fool-proof sampling device that can take both point samples and a composite or integrated sample across a range of depths. I have now created such a design and a method of using it as will be described herein. 
   SUMMARY OF THE INVENTION 
   My invention is a multipurpose vertical aqueous sampler and a method of using it to collect both point and integrated samples of fluids in bodies of fluids, such as rivers, ponds, swamps, lakes, oceans and the like. In one embodiment the sampling device of my invention comprises a tube or other hollow structure capable of holding a fluid sample. A stopper located at the bottom of the tube is connected to a central shaft that is used to open and close the stopper. A slotted sleeve is attached at the bottom end of the tube which allows fluid to enter the tube when the stopper is placed in an open or semi-open position. The sampling device also has two lines attached, one for lowering the tube in the body of fluid and one is attached to the shaft for toggling the stopper from an open to a closed position and for retrieving the device from the body of fluid. 
   The tube can be constructed of any material that can withstand immersion into the fluid being sampled. Preferably, the tube is constructed of a transparent material such as clear acrylic, glass, Plexiglas or other synthetic plastic material that allows for easy visual observation of a collected sample. Other materials such as PVC, metal or ceramics could be used if desired. The preferred shape of the tube is circular, but depending on the design of the stopper other shaped tubes (oval, square, triangular, etc.) will work equally well. The stopper must be designed to fit snugly into the bottom end of the tube when in the closed position to provide a tight seal and to prevent a collected sample from leaking out of the tube. A preferred material of construction of the stopper is rubber or other compressible material such as cork or a like material, however, the exact material of construction is not critical to the invention as long as it provides a tight seal and does not adversely affect the sample being collected through decay, dissolution or contamination. The slots in the sleeve allow the flow of fluid into the device when the stopper is placed in a open position. Partial opening of the stopper allows for a controlled flow of fluid into the device. My sampling device may optionally contain a sample port positioned at the lower end of the device. This sample port provides a convenient means to withdraw a measured portion of the acquired fluid sample for analysis. Likewise, the tube may optionally contain graduated markings that will signify the volume of a fluid inside the tube and/or the depth of sampling. My sampling device may optionally be outfitted with a ballast at the end of the slotted sleeve, attached to a removable holding ring. Use of the ballast is recommended when collecting water samples in waters with strong currents. Another optional feature is a set of two flaps at the top head of the sampler that automatically close upon retrieval of the sampler to help protect the integrity of the sample. 
   As mentioned, my invention also involves a method of using my sampling device to collect both point and integrated samples. To collect a point sample the stopper of my device is placed in the closed position. The device is then pushed down to a predetermined depth in a body of fluid (depth no more than the length of the sampler). Once the desired depth is reached, the stopper is opened to allow fluid to enter the tube through the slotted sleeve. Once the tube is filled with fluid the stopper is closed and the device is withdrawn from the body of fluid using a line attached to a shaft connected to the stopper. For collecting an integrated sample of fluid across a range of depths the stopper is first placed in an open position and then lowered into the body of fluid. As the sampler device descends, fluid enters the slotted sleeve and into the tube. When the bottom of the device reaches the final desired depth, the shaft is toggled to close the stopper to prevent further collection of fluid. With the stopper in the closed position the device can then be retrieved using a line attached to a shaft connected to the stopper The result of this method of sample collection is that small portions of fluids are collected beginning at the surface (or sub-surface) and continues as the device descends to a final depth. When the integrated sample collection method is used, two types of samples may be retrieved from the tube. If a composite of the fluid collected across the depth range is desired, then the stopper is opened and the entire contents of the tube is emptied and mixed into another container where single samples are taken for analysis. Alternatively, if a stratified sub-sampling analysis is desire, the tube is maintained in a vertical orientation after retrieval from the body of fluid (matching that of when the sample was collected) and placed in a deck stand to maintain that orientation with the stopper in the closed position. Single sub-samples can then be removed using the optional sample port located at the bottom of the tube. In this way the first samples taken from the sample port will represent fluid taken at the deepest depth of the depth range covered during the integrated sampling method. 
   The invention may take form in various parts and arrangement of parts. The drawings are only for purposes of illustrating preferred embodiments and are not to be construed as limiting the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a perspective view of one embodiment of my sampling device. 
       FIG. 2  schematically shows the integrated sampling technique of my invention. 
       FIG. 3  schematically shows sub-sampling of a fluid collected using a integrated sample collection method. 
       FIG. 4  schematically shows the single-depth point sampling technique of my invention. 
       FIG. 5  schematically shows an embodiment collecting an integrated sample of fluid. 
   

   DESCRIPTION OF PREFERRED EMBODIMENTS 
   Reference will now be made to the Figures accompanying this application to further describe my invention. 
     FIG. 1  shows sampling device  10  of my invention in a vertical orientation as it would be deployed to sample a body of fluids. A circular tube  1  has an upper end  3  and a lower end  2  and is shown connected to slotted sleeve  11 . Optional sample port  9  is located at lower end  2 . Stopper  4  is connected to shaft  5  at lower end  2  and is designed to slide easily, guided by the slotted sleeve  11 .  FIG. 1  shows the stopper in the open position where the slots in sleeve  11  provide an opening in the bottom end  2  of tube  1 . Top head  8  is attached to the upper portion  3  of the tube and contains a cross member that acts as a guide for shaft  5 . Line  7  is attached to shaft  5  and is used to retrieve the device after a sample is taken and to assist in toggling the shaft and stopper between open and closed positions. Line  6  is attached to top head  8  and is used to lower the device when in the opened position, into a body of fluid to a desired depth. 
     FIG. 2  illustrates operation of my invention for collecting a vertically integrated sample. View  20  shows device  10  being lowered in direction  21  into a body of fluid  25  with stopper  4  in the open position. As soon as the device breaks the surface of body of fluid  25 , fluid enters the slots of sleeve  11  and begins to fill the tube. As the device continues in direction  21  more and more fluid  25  enters the tube. Once a desired depth is reached, as illustrated by view  30 , line  7  is pulled in direction  31  which in turn moves the shaft and causes stopper  4  to reach a closed position thus preventing any further fluid from entering the tube. Line  7  is further pulled in direction  31  until the device is completely removed from body of fluid  25 . 
     FIG. 3  illustrates one method of sub-sampling the fluid collected in device  10  obtained using the integrated sampling technique. First, device  10 , full of the fluid sample, is maintained in same vertical orientation that it was during sample collection and placed in deck stand  72 . Optional sample port  9  is then opened and fluid  70  is removed to vessel  71  for analysis. Because sample port  9  is located at the bottom end of device  10 , the first fluid  70  removed will correspond to the last fluid collected at the deepest depth. Throughout the sub-sampling collection process stopper  4  remains in the closed position. 
     FIG. 4  illustrates the “point” sampling technique of my invention. View  40  shows device  10 , with the tube empty and with the stopper in the closed position, being pushed into fluid  25  in direction  41  to a predetermined depth. Once at the desired depth, as shown in view  50 , the stopper is moved in direction  51  to an open position. Fluid fills the tube and the stopper is then closed. View  60  shows the filled device being retrieved in direction  61  from fluid  25 . 
     FIG. 5  illustrates an embodiment of my invention using an optional ballast  80  attached to device  10  through connector  81 . Also shown in this embodiment are optional flaps  83  that remain open during sampling, but closed during retrieval of the device. Flaps  83  automatically close over openings  82  when the sampling device is pulled upward through the body of fluid. 
   It should be understood that the embodiments and examples disclosed herein are presented for illustrative purposes only and that many other combinations and articles that embody the methods, formulations and systems will be suggested to persons skilled in the art and, therefore, the invention is to be given its broadest interpretation within the terms of the following claims: