Abstract:
A liquid pump for pumping groundwater samples from small diameter sub-terrain wells, comprising a tubular casing having inlet apertures, a top cap provided with a fluid communication port and a liquid outlet port, a top bladder mandrel secured to the top cap, a mandrel sealing member disposed in a lower end of the casing, a bottom bladder mandrel secured to the mandrel sealing member, and a flexible bladder extending between the top bladder mandrel and the bottom bladder mandrel and defining a liquid chamber for receiving the liquid therein and a fluid chamber for receiving a fluid under pressure therein that surrounds the liquid chamber, with the bladder disposed therebetween. The fluid chamber is in fluid communication with the fluid communication port connected to a source of the actuating gas, while the liquid chamber is in one-way fluid communication with the liquid inlet and the liquid outlet port.

Description:
RELATED APPLICATIONS 
     This is a continuation-in-part of U.S. application Ser. No. 09/512,295, filed Feb. 24, 2000, U.S. Pat. No. 6,382,933. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to liquid pumping and collecting apparatuses, and more particularly to a bladder pump for pumping underground liquid, such as groundwater samples, from small diameter wells. It should be noted, however, that the invention is also applicable and adaptable in various other applications that will occur to one skilled in the art from the disclosure herein. 
     2. Description of the Prior Art 
     Recent increases in public concern for the environment have resulted in various government-imposed environmental regulations with regard to groundwater quality and land-site cleanup projects. Among such regulations are requirements relating to the monitoring and sampling of water quality of aquifers as sources of drinking water. In response to these requirements, water quality analytic capabilities have been improved and water-sampling equipment has been developed. However, presently most sampling using bladder pumps employ permanently installed dedicated pumps in monitoring wells. Current portable equipment for the groundwater sampling is relatively heavy, bulky, and thus difficult to transport from one monitoring site to another. 
     One of the preferred types of pumps for groundwater sampling or other pumping applications is a submersible, fluid-actuated pump wherein the actuating fluid is preferably a gas such as compressed air. A flexible bladder member in this type of pump separates and isolates the interior of the pump into two chambers: a liquid chamber that contains the sample fluid and is in communication with both the pump inlet and outlet, and a gas chamber surrounding the first chamber, and connected to a source of the actuating gas, with the bladder disposed therebetween. The pumped liquid is conveyed through the pump by alternately pressurizing and venting or relieving the pressure in the gas chamber to contract and relax the bladder member, thus alternately decreasing and increasing the volume of the liquid chamber. The pumped liquid is drawn into the liquid chamber during such increases in volume under the influence of the natural hydrostatic head of the groundwater or other pumped liquids and is discharged through the pump outlet during such decreases in volume, thereby conveying the pumped liquid through the pump. 
     The conventional bladder pumps have proven to be not very efficient, however, in obtaining consistent, non-contaminated water samples that are accurately representative of the water system from which the sample is taken. The inadequacies of previous sampling equipment stem largely from such causes as cross-contamination between sampling sites, ineffective and inconsistent field cleaning methods, contamination due to equipment handling, and inconsistent well depth sampling. In addition to presenting sample quality problems, much of the previous equipment has been heavy and bulky and thus difficult to transport from one monitoring site to another. 
     Moreover, conventional bladder pumps for groundwater sampling have proved to be complicated to operate, relatively expensive, and impractical for sampling at remote locations where site access is severely limited. The need therefore exists for more efficient and easy to operate liquid sampling bladder pumps. 
     SUMMARY OF THE INVENTION 
     The present invention alleviates the drawbacks of the prior art. The present invention provides a pump for a wide variety of applications, including, but not limited to, groundwater quality applications, withdrawing and collecting contaminated groundwater or other subterranean liquids from a landfill-site having a plurality of in-ground wells. The novel pump may be built with a small outside diameter, such as 1.315″, and is adapted to sample temporarily and/or permanently installed small diameter monitoring wells. The bladder pump of the present invention is particularly effective for conducting “low-flow sampling” from monitoring wells where minimal purging is undertaken prior to sample collection. Please note that low-flow refers to the velocity with which water enters pump intake and that is imparted to the formation pore water in the immediate vicinity of the well screen. 
     The preferred liquid sampling pump is an air-operated, gas-displacement bladder pump having a generally tubular casing submersible in the in-ground well. The pump body includes a liquid inlet with an inlet check valve for allowing one-way fluid flow from the in-ground well into the housing interior, and a liquid outlet with an outlet check valve allowing one-way fluid flow from the pump body interior to the discharge collection equipment. The liquid sampling pump further includes a top cap attached to an upper end of the casing and provided with a fluid communication port and a liquid outlet port, a top bladder mandrel secured to the top cap, a mandrel sealing member disposed in a lower end of the casing and defining an inlet chamber within the lower end thereof, a bottom bladder mandrel secured to the mandrel sealing member, and a flexible bladder extending between the top bladder mandrel and the bottom bladder mandrel and defining a liquid chamber for receiving the liquid therein and a fluid chamber for receiving a fluid under pressure therein that surrounds the liquid chamber, with the bladder disposed therebetween. The fluid chamber is in fluid communication with the fluid communication port that is connected to a source of the actuating gas, while the liquid chamber is in one-way fluid communication with the liquid inlet and the liquid outlet port. 
     The sample fluid is conveyed through the pump by alternately pressurizing and venting or relieving the pressure in the second chamber to contract and relax the bladder member, thus alternately decreasing and increasing the volume of the first chamber. Sample liquid is drawn into the liquid chamber during such increases in volume under the influence of the natural hydrostatic head of the groundwater and is discharged through the liquid outlet port during such decreases in volume, thereby conveying the sample liquid through the pump. The components of the pump are preferably composed of low-cost, lightweight synthetic materials that are non-corrosive and do not otherwise affect the chemical composition of the sampled fluid. 
     Additional advantages and features of the present invention will become apparent from the following description and the appended claims taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects and advantages of the invention will become apparent from a study of the following specification when viewed in light of the accompanying drawings, wherein: 
     FIG. 1 is a fragmentary longitudinal sectional view of a liquid sampling system of the present invention; 
     FIG. 2 is a perspective view of a controller apparatus of FIG. 1; 
     FIG. 3 is a fragmentary cross-sectional view of a liquid sampling pump in accordance with the preferred embodiment of the present invention; 
     FIG. 4 is a cross-sectional view of a top cap in accordance with the preferred embodiment of the present invention; 
     FIG. 5 is a cross-sectional view of a mandrel sealing member in accordance with the preferred embodiment of the present invention; 
     FIG. 6 is a cross-sectional view of a bottom bladder mandrel in accordance with the preferred embodiment of the present invention; 
     FIG. 7 is a cross-sectional view of an inlet check valve in accordance with the preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     FIG. 1 of the drawings illustrates an underground liquid sampling system of the present invention indicated generally by reference numeral  1 . For purposes of illustration, the liquid sampling apparatus is shown as installed in a monitoring well  2 . A liquid sampling pump  10  is disposed within the well casing  4  of the monitoring well  2  and is submerged beneath the level of the groundwater  6  to a suitable depth for obtaining representative groundwater samples. 
     As is explained in further detail below, the liquid sampling pump  10  in accordance with the present invention, is a bladder-type fluid-actuated pump, wherein the actuating fluid is a pressurized gas, preferably compressed air, and includes a plurality of inlet openings  39 , an outlet fitting  14 , and a fluid fitting  20 . 
     A liquid conduit  16  is sealingly connected at one end to the pump outlet fitting  14  to provide direct sample delivery to a sample collection vessel  17 . A pressurized gas conduit  18  is connected at one end to the fluid fitting  20  of the pump  10 . The other end of the gas conduit  18  is selectively and removably connected to a precision dual range controller  100 . 
     Because the pump is of a relatively lightweight construction, the conduits themselves can frequently be used to hold and retain the pump in its submerged position in the well  2 . Preferably, the pump  10  is provided with a support rod  15  (shown in FIG. 3) that allows users to suspend the sampling pump  10  in the well  2  with a covered steel cable (not shown). It will be appreciated that any other appropriate means for holding and retaining the pump  10  in its submerged position in the well  2 , commonly known to those skilled in the art, may be used. 
     The precision dual range controller  100  is selectively and removably connected to the sampling pump  10  by means of the external gas conduit  18 . The preferred controller  100  is a portable, lightweight unit and includes means for alternately positively pressurizing and venting or relieving the pressure of the actuating gas in order to operate the liquid sampling pump  10 , as is explained below. 
     FIG. 2 illustrates a preferred physical arrangement for the dual range controller  100 , including a carrying case  102  for housing and transporting the portable controller apparatus from one monitoring site to another. The carrying case  102  generally includes an upper portion  104  hingedly connected to a base portion  106 , carrying handle (not shown), and upper and lower latches  110  and  112 . The carrying case  102  is preferably composed of high impact-resistant materials known to those skilled in the art for purposes of protecting the components of the controller  100 . The dual range controller generally includes two separate, switchable, pressure regulated air supply circuits, preferably 0-50 psi and 0-100 psi, each having a dedicated pressure gauge  122  and  123  respectively, a fitting  120  to which the external gas conduit may be connected, a pressure gauge  118  used to monitor the air supply provided to the controller  100 , and various controls. To enable precision control of the flow from the bladder pump, the controller  100  is provided with separate precision electronic timers to control the flow air to and from the pump  10 , each of which is adjustable in the range of 0.1 to 10 seconds. The carrying case  102  is especially adapted for ease and convenience of transportation of the controller and related components to monitoring sites to which access is limited or difficult. 
     The various individual components of the preferred controller apparatus  100  are well known to those skilled in the art and thus are described only schematically in terms of their functions. 
     As illustrated in FIG. 3, the liquid sampling pump  10  in accordance with the preferred embodiment of present invention includes a generally tubular pump casing  30  having a cylindrical wall  32 , a lower end  34  and an upper end  35 . The lower end  34  of the pump casing  30  is sealed with a bottom plug  38  press fitted or otherwise secured to the lower end  34  of the tubular pump casing  30  in any appropriate manner known to those skilled in the art. The bottom plug  38  may include an embedded weight in order to insure appropriate orientation of the sampling pump  10  within the well  2 . The lower end  34  of the tubular casing  30  is further provided with at least one liquid inlet, preferably in the form of the circular inlet openings  39  in the wall  32 . Preferably, the tubular pump casing  30  is provided with four inlet openings  39 , however, any other appropriate number of openings  39  is within the scope of the present invention. 
     The upper end of the pump casing  30  is sealingly closed with a top cap  40  secured to the upper end  35  of the tubular pump casing  30  in any appropriate manner known to those skilled in the art, such as press-fitting. The top cap  40  is sealed to an internal surface of the wall  32  by means of O-rings  42  or other suitable sealing means known to those skilled in the art. The top cap  40 , illustrated in detail in FIG. 4, is further provided with an outlet liquid port  44 , and a fluid communication port  46 . The outlet fitting  14  is affixed to the liquid outlet port  44 . Similarly, the fluid fitting  20  is affixed to the fluid communication port  46 . The fittings  14  and  20  are identical and may be conventional threaded fittings or any other appropriate fittings well known in the prior art. 
     Further in accordance with the present invention, the top cap  40  is provided with an outlet check valve  50  for preventing backflow of the pumped liquid through the outlet liquid port  44 . The outlet check valve  50  generally includes a valve seat  52 , preferably integrally formed within the outlet liquid port  44 , and a valve closure member complementary to the valve seat  52 . Preferably, as shown in FIGS. 3 and 4, the valve closure member is in the form of a substantially spherical ball member  54 . Such an arrangement allows disassembling of the inlet check valve  50  by the user for cleaning when required. It will be appreciated by those skilled in the art that any other appropriate shapes of the valve closure member, such as conical, are within the scope of the present invention. 
     Secured to the top cap  40  is a top bladder mandrel  55  extending through a bore  45  in the outlet liquid port  44 . The top bladder mandrel  55  is provided with an axial communication passage  56  therethrough in fluid communication with the outlet liquid port  44 . The top bladder mandrel  55  is preferably threadedly attached to the top cap  40 . In this case, the bore  45  of the outlet liquid port  44  is provided with appropriate screw threads. It will be appreciated that the top bladder mandrel  55  may be secured to the top cap  40  in any appropriate manner known to those skilled in the art. 
     As further illustrated in FIG. 3, the sampling pump  10  also includes a mandrel sealing member  60  disposed within the lower end  34  of the tubular pump casing  30  between the bottom plug  38  and the top cap  40 . The mandrel sealing member  60  sealingly engages an inner peripheral surface of the wall  32  by means of O-rings  62 , and defines an inlet chamber  48  within the lower end  34  of the casing  30  between the bottom plug  38  and the sealing member  60 . As shown in FIG. 3, the groundwater enters the inlet chamber  48  through the inlet openings  39 . 
     As illustrated in details in FIG. 5, the mandrel sealing member  60  includes a substantially cylindrical body  61  provided with annular grooves  63  integrally formed on an outer peripheral surface thereof. The annular grooves  63  are adapted to receive the O-rings  62  therein, as shown in FIG.  3 . The mandrel sealing member  60  further has a central opening  64  therethrough including a substantially conical sealing surface  65 . 
     Secured to the mandrel sealing member  60  is a bottom bladder mandrel  66  extending through the central opening  64  therein. Preferably, as illustrated in detail in FIG. 6, the bottom bladder mandrel  66  includes a body  68  provided with an axial communication passage  70  therethrough, a substantially cylindrical threaded end portion  72 , a substantially conical sealing surface  74 , a substantially cylindrical bladder mounting surface  76  provided with annular grooves  77  are adapted to receive O-rings therein, and a nose portion  78 . It will be appreciated that the conical sealing surface  74  is adapted to engage the conical sealing surface  65  of the mandrel sealing member  60 , and is substantially complementary thereto. The body  68  of the bottom bladder mandrel  66  further includes a plurality of radial apertures  71  in fluid communication with the axial communication passage  70 . 
     The bottom bladder mandrel  66  is secured to the mandrel sealing member  60  by a nut member  79  threaded onto the end portion  72  of the body  68  of the bottom bladder mandrel  66 . 
     Further in accordance with the present invention, secured to the bottom bladder mandrel  66  is an inlet check valve  90  adapted for preventing backflow of the pumped liquid through the an axial communication passage  70  thereof. Preferably, as illustrated in detail in FIG. 7, the inlet check valve  90  includes a body  92  having an axial bore  94  therethrough, a valve seat  96 , preferably integrally formed within the axial bore  94 , and a valve closure member complementary to the valve seat  96 . Preferably, as shown in FIGS. 3 and 7, the valve closure member is in the form of a substantially spherical ball member  98 . It will be appreciated by those skilled in the art that any other appropriate shapes of the valve closure member, such as conical, are within the scope of the present invention. Preferably, an upper end portion of the bore  94  is provided with screw threads  95  adapted to threadedly engage complementary threads  72  on the threaded end portion  72  of the bottom bladder mandrel  66 , thus removably securing the inlet check valve  90  to the bottom bladder mandrel  66 . Such an arrangement allows disassembling of the inlet check valve  90  by the user for cleaning when required. It will be appreciated that the inlet check valve  90  may be secured to the bottom bladder mandrel  66  in any other appropriate manner known in the art, such as press-fitting, adhesive bonding, etc. 
     The interior of the pump casing  30  is divided and isolated into two chambers by a generally cylindrical flexible bladder  80  having a central portion  81  and two opposite ends  82 ′ and  82 ″. The bladder  80  defines a liquid chamber  84  in its interior and a substantially annular fluid chamber  86  between an exterior of the bladder  80  and an interior wall surface of the pump casing  30 . The bladder  80  is sealingly connected to the top bladder mandrel  55  at its upper end  82 ′ by means of O-rings  57  and a band clamp  59 , and to the bottom bladder mandrel  66  at its lower end  82 ″ by means of O-rings  75  and a band clamp  73 . The band clamps  59  and  73  may be composed of any appropriate materials known to those skilled in the art. 
     The top bladder mandrel  55  and the bottom bladder mandrel  66  are interconnected by a support member  87 . Preferably, the support member  87  is a solid rod made of a plastic material or stainless steel coated with polytetrafluoroethylene (PTFE) marketed under the DuPont Teflon® trademark. In this case, the top bladder mandrel  55  includes a number of radial communication apertures  58  providing the free flow of groundwater liquid between the liquid chamber  84  and the passage  56  in the top bladder mandrel  55 . Similarly, the radial apertures  71  in the bottom mandrel  66  provide the free flow of groundwater liquid between the liquid chamber  84  and the passage  70 . 
     Alternatively, the support member  87  may be in the form of a hollow tube provided with a number of apertures spaced at various locations along its longitudinal length in order to allow the free flow of groundwater fluid between the interior of the tube and the remainder of the liquid chamber  84 . 
     As is apparent from the embodiment depicted in FIG. 3, the liquid chamber  84  within the flexible bladder  80  is in fluid communication with the liquid outlet port  44  of the top cap  40  through the communication passage  56  and the apertures  58  in the top bladder mandrel  55  and the outlet check valve  50 . Furthermore, the liquid chamber  84  is in fluid communication with the inlet chamber  48  through the passage  70  and the apertures  71  in the top bladder mandrel  55  and the inlet check valve  90 . On the other hand, the annular fluid chamber  86  is in fluid communication with the fluid communication port  46  of the top cap  40 . 
     As illustrated in FIG. 3, the bladder  80  is formed with the reduced diameter ends  82 ′ and  82 ″ relative to the central portion  81  thereof. This allows for an increased stroke volume and, therefore, increased efficiency of the pump operation. 
     As further illustrated in FIG. 3, the liquid inlet apertures  39  in the wall  32  are located substantially between the bottom plug  38  and the mandrel sealing member  60 . Preferably, the inlet apertures  39  are located in close proximity to each other forming a limited sampling area. This allows the pump  10  to sample a narrow stratum of liquid in the monitoring well. A mesh screen filter  37 , preferably, of inert corrosion resistant material, such as plastic or stainless steel, is disposed within the casing  30  adjacent to the apertures  39  for filtering out solids greater than a predetermined size. 
     When the pumped liquid, such as groundwater, is flowing through the pump in the direction indicated by flow arrows  88 , the groundwater passes through the outlet check valve  50  and through the outlet port  44  to the outlet fitting  14 . The outlet check valve  50  in the top cap  40  substantially prevents backflow in the direction opposite that indicated by flow arrows  88 . Correspondingly, the inlet cone-shaped check valve  90  prevents backflow of groundwater or other pumped liquid from the liquid chamber  84  through the axial communication passage  70  in the bottom bladder mandrel  66  into the inlet chamber  48 . 
     In operation, the fluid sampling pump  10  of the present invention is actuated by means of actuating gas supplied to the fluid chamber  86  which is alternately and sequentially subjected to positive and negative or reduced pressures. The alternate pressurizing and depressurizing of the actuating gas in the fluid chamber  86  causes the bladder  80  to alternately expand and contract, thus alternately and sequentially decreasing and increasing the volume of the liquid chamber  84 . During such increases in volume, the groundwater is drawn from the well  2  into the liquid chamber  84  through the inlet apertures  39  in the casing  30  and the axial communication passage  70  in the bottom bladder mandrel  66 . During such decreases in such volume, the groundwater is forced out of the liquid chamber  84  through the passage  56  in the top bladder mandrel  55  and the outlet port  44  in the top cap  40  and is passed through the outlet fitting  14  and the groundwater conduit  16  to be collected in the sample collection vessel  17 . The check valves  50  and  90  prevent the water from being discharged through the inlet apertures  39  or drawing in through the outlet port  44 . 
     The capacity of the pump  10  may be changed in different versions of the pump by changing the diameter of the tubular pump casing  30 , thereby changing the amount of water drawn in and forced out during the alternate contractions and relaxations of the flexible bladder  80 . Preferably, the bladder pumps in accordance with the present invention is manufactured with the outside diameter 1.315″. Theoretically, increasing the length of the pump wall  32  and correspondingly increasing the length of the bladder  50  would also increase the stroke volume. However, the longer pumps are subject to hang up in the non-plumb monitoring wells. For this reason, the bladder pumps for well monitoring ought to be designed as short as possible, such as 7.4″. 
     It should be noted that the various components of the pump  10 , contacting the pumped liquid, are preferably composed of relatively lightweight and low-cost synthetic materials that will not be corroded when exposed to the groundwater and that will not otherwise affect the composition of the groundwater flowing through the pump. Examples of such materials include stainless steel, rigid polyvinyl chloride (PVC), DELRIN and polytetrafluoroethylene (PTFE) marketed under the DuPont Teflon® trademark. The flexible bladder  80  is preferably composed of a flexible synthetic material that also will not corrode or affect the composition of groundwater flowing therethrough, such as PTFE, or Teflon®. The casing  30  of the pump is preferably made of PVC. The ball members  54  and  98  of the ckeck valves  50  and  90  respectively, are preferably made of PTFE, or Teflon®. One skilled in the art will readily recognize, however, that the various components of the fluid sampling apparatus may be composed of other suitable non-corrosive materials. 
     Therefore, the novel arrangement of the liquid sampling bladder pump of the present invention as constructed in the above-described embodiments provides simplified field application and easy deployment in non-plumb wells, and allows for obtaining representative samples of groundwater or other liquids. 
     The foregoing description of the preferred embodiments of the present invention has been presented for the purpose of illustration in accordance with the provisions of the Patent Statutes. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obvious modifications or variations are possible in light of the above teachings. The embodiment disclosed hereinabove was chosen in order to best illustrate the principles of the present invention and its practical application to thereby enable those of ordinary skill in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated, as long as the principles described herein are followed. Thus, changes can be made in the above-described invention without departing from the intent and scope thereof. It is also intended that the scope of the present invention be defined by the claims appended thereto.