Abstract:
A float valve assembly has a liquid passage with upper and lower ends opening to upper and lower liquid receiving spaces, valve seats about the upper and lower ends of the passage, and upper and lower float valves within the spaces movable into and from seating contract with the valve seats to open and close the passage ends in response to rising and lowering liquid levels in the spaces. The opening movement of one float valve is adjustable to regulate flow rate through the passage.

Description:
This application is a divisional of Ser. No. 08/421,474, filed Apr. 12, 1995, entitled &#34;Liquid Sampling Devices and Method&#34;, now U.S. Pat. No. 5,524,495, which is a continuation of Ser. No. 08/075,215, filed Jun. 9, 1993, now abandoned, which is a continuation-in-part of Ser. No. 07/902,067, filed Jun. 22, 1992, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to the art of sampling a liquid for the purpose of analyzing the liquid to determine its composition. The invention relates more particularly to novel liquid sampling methods and devices for this purpose. 
     2. Prior Art 
     It will become readily evident as the description proceeds that the liquid sampling methods and devices of this invention may be utilized for a variety of liquid sampling purposes and to sample a variety of liquids in a variety of sampling environments. One sampling application of the invention which is of particular importance at the present time involves sampling storm water runoff from industrial property to determine the presence of toxics and other contaminants, if any, in the runoff. Another useful application involves sampling liquid leakage from industrial liquid processing equipment to aid in locating the leak(s). The invention will be described in the context of these particular applications. Other possible uses of the invention will be mentioned and involve sampling liquid in a storm drain system or other liquid conductor, sampling liquid dicharge from a sewage treatment plant or an industrial process or the like, and sampling liquid in a body of liquid. The invention may be utilized to sample liquids from any type of fluid conductor including surfaces, open channels, or closed pipes or ducts, and liquids which are either homogenous liquids, mixtures of miscible liquid components, or mixtures of immiscible liquid components. 
     The water flowing through public storm drain systems often contains toxic and other contaminants which end up polluting large public water bodies, such as the San Diego, Santa Monica, and San Franscisco Bays in California. Much of this contamination is due to deliberate and illegal dumping of industrial waste products into the storm drain systems in order to avoid the problems and cost associated with legal disposition of such waste procucts. The liquid sampling methods and devices of this invention may be utilized to sample the water flowing through these storm drain systems for the purpose of determining the presence and source of such contaminants. 
     Another extensive source of contamination of the water in storm drain systems is storm water runoff from industrial property and the like. Thus, the ground and other exterior surfaces of such property are often covered by or contain a relatively high concentration of various industrial substances due to spillage of the substances onto the surfaces and the ground, leakage of the substances into the soil from pipes or storage containers, and hosing of the substances from interior floor areas onto exterior surface areas and the ground. During a rainstorm, these substances are entrained in the storm water runoff from the property and are carried with the storm water runoff into the public storm drain system. 
     In an effort to reduce such storm water runoff pollution, the state of California recently passed legislation establishing a program entitled the Industrial Storm Water Permitting Program. This program requires industrial property owners to obtain a permit, referred to as a General Industrial Storm Water Permit, for storm water runoff or discharge from their properties into the public storm drain system. The permits are issued through the State Water Resources Control Board. 
     Obtaining such a permit involves the payment of an annual fee and the performance by each applicant, referred to as a discharger, of certain obligations. These obligations include the following: (a) preparation of a site map of the property in question, starting with the roof each building on the property, showing the flow path of storm water runoff from the roof to the ground, then across the ground into the drain system on the property, and then from the property drain system into the public storm drain system; (b) visual observation of storm water discharge from the property during both the wet season (October through April) and the dry season (May through September); (c) submission of an estimate or calculation of the storm water discharge volume during two significant storm events in the wet season; (d) submission, for approval, of a proposed storm water sampling program; (e) execution of the approved storm water sampling program in compliance with the state regulations to obtain certain storm water samples; and (f) submission of the storm water samples for analysis. 
     Requirement (e) above of the Industrial Storm Water Permitting Program dictates that storm water samples be obtained during two separate storm events of the wet season and that one of these events be the first storm event of the wet season which produces significant storm water runoff preceded by at least 72 hours of dry weather. The storm water samples collected during each storm event must include a &#34;grab sample&#34; and a &#34;composite&#34;. A grab sample is a storm water sample taken during the first thirty minutes of the discharge (or within the first hour of the discharge with explanation). A composite sample may be a sample taken with a continuous sampler or the combination of at least three grab samples taken during each hour of discharge with the successive grab samples being separated by a minimum period of at least 15 minutes. A composite sample shall be either flow-weighted (i.e. consist of a mixture of aliquots collected at constant time intervals, where the volume of each aliquot is proportional to the flow rate of the discharge) or time-weighted (i.e. consist of a mixture of equal volume aliquots collected at constant time intervals). Grab samples are used for determining certain specific contamination levels. Composite samples are used to obtain an estimate of average runoff water quality. 
     From the above discussion, it is evident that storm water sampling in compliance with the above-stated requirements of the Industrial Storm Water Permitting Program presents two basic problems. These problems are (a) having a storm water sampler in proper sampling readiness and position at the start of the first significant storm event of a wet season to collect a sample of the storm water runoff during the first 30 minutes of the discharge which will qualify as a valid &#34;grab sample&#34;, and (b) having a storm water sampler in proper sampling readiness and position at the start of the first storm event of a wet season to collect a sample or samples of the storm water discharge during the first 3 hours of the discharge which will qualify as a valid &#34;composite sample&#34;. 
     One way in which such valid grab and composite samples may be assured, of course, is to have persons standing by 24 hours a day during each and every day preceding the wet season in constant readiness to place storm water samplers in proper sampling positions immediately upon the start of each storm event to be monitored. 
     Obviously, this is an impractical solution to the storm water sampling problem. Moreover, there are numerous other situations in which liquid sampling is desirable or essential and which involve essentially the same or other similar sampling problems and requirements as storm water runoff sampling. Accordingly, there is a definite need for liquid sampling methods and devices for these and other liquid sampling purposes. 
     SUMMARY OF THE INVENTION 
     This invention provides novel liquid sampling methods and devices which satisfy the requirements of the Industrial Storm Water Permitting Program and yield storm water grab samples and time composite samples that comply with such requirements. Accordingly, the sampling methods and devices are ideally adapted for storm water sampling. In this regard, for example, the sampling devices may be placed in sampling position well before the onset of the wet season where they remain in total readiness, without human attention, to collect a storm water grab sample and/or a storm water time composite sample within the prescribed times during the first storm event of the wet season or during a later storm event to be monitored. 
     While ideally adapted for storm water sampling, the liquid sampling methods and devices of the invention are uniquely capable of many other diverse liquid sampling uses, some of which will be discussed or mentioned later. According to its broader aspects, therefore, the invention provides liquid sampling methods and devices for collecting samples of any liquid for any purpose. The liquid sampled may be a homogeneous liquid, a mixture of immiscible liquid, or a mixture of miscible liquids. 
     Simply stated, a liquid sampling device according to the invention, referred to in places simply as a liquid sampler, comprises a receptacle having a normally lower sample collection chamber, normally upper inlet means having an inlet passage through which liquid to be sampled can enter the chamber, and a drain valve through which a collected sample can be drained from the chamber. In use, the sampler is placed in a sampling position wherein the inlet passage is disposed to receive the liquid to be sampled. 
     The described sampling devices of the invention are intended for storm water sampling, leak sampling, and other similar sampling uses and have an upper catch basin into which the inlet passage opens. For storm water sampling, the sampler is placed in sampling position within a sump or the like located in the anticipated flow path of storm water runoff from the property to be monitored. At least some of the storm water flowing into the sump enters the sampler basin and then flows from the basin through the sampler inlet passage into the sampler collection chamber. For leakage sampling, the sampler is similarly placed in sampling position in a sump in the floor along which the leakage liquid flows. In other liquid sampling applications, a sampling device according to the invention may be positioned to sample liquid effluent from or flow through a pipe, channel, or other fluid conductor or immersed in a body of the liquid to be sampled. After the desired sample has been collected, the sampler is removed to a laboratory where the collected sample is drained from the sampler and analyzed. 
     According to one important feature of the invention, the inlet means of the sampling device includes inlet valve means for opening and closing the inlet passage to the collection chamber. This inlet valve means has a standby mode in which the valve means close the inlet passage against entry of foreign matter into the collection chamber, a sampling mode in which the inlet valve means open the inlet passage for entry of the liquid being sampled into the collection chamber, and a sample containment mode in which the inlet valve means close the inlet passage against liquid entry into and escape of liquid and vapor from the collection chamber. The inlet valve means assumes its standby mode in the absence of liquid covering the upper inlet end of the inlet passage. The inlet valve means assumes its sampling mode when the inlet end of the inlet passage is covered with liquid and the collection chamber contains less than a predetermined volume of liquid, that is when the liquid level in the collection chamber is below a predetermined level. The inlet valve means assumes its sample containment mode when the collection chamber contains at least the predetermined volume of liquid, that is when the liquid level in the collection chamber at least equals the predetermined level. 
     In the described embodiments of the invention, the inlet valve means comprise an upper float valve engagable with an upper valve seat about the upper end of the inlet passage and a lower float valve engagable with a valve seat about the lower end of the inlet passage. The upper float valve is movable between a lower closed position wherein the upper valve engages the upper valve seat to close the upper end of the inlet passage and an upper open position wherein the upper float valve is spaced upwardly from the upper valve seat to open the upper end of the inlet passage. The lower float valve is movable between an upper closed position wherein the lower valve engages the lower valve seat to close the lower end of the inlet passage, and a lower open position wherein the lower float valve is spaced downwardly from the lower valve seat to close the lower end of the inlet passage. 
     When the sampling device occupies its normal upright position with the upper catch basin and lower collection chamber empty, the lower float valve remains in its lower open position and thereby opens the lower end of the inlet passage. The upper float valve, on the other hand, remains in its lower closed position and seals the upper end of the inlet passage against entrance of foreign matter into the collection chamber during storage and handling of the device and prior to the basin receiving liquid to be sampled after placement of the device in sampling position. 
     When the liquid level in the basin rises to the height of the upper end of the inlet passage, the liquid lifts the upper float valve off its valve seat and enters the collection chamber through the inlet passage. If liquid inflow into the basin continues, the collection chamber will eventually fill with the liquid to a level sufficient to elevate the lower float valve to its closed position and thereby seal the lower end of the inlet passage even though the upper float valve remains open. This closure of the lower float valve occurs in response to accumulation of a liquid sample of predetermined volume in the collection chamber, and prevents subsequent dilution of the collected sample by continued liquid flow into the sampler basin or by deliberate action of a person seeking to falsify the sample. Closure of the lower valve also prevents escape of liquid vapor from the collection chamber. 
     The disclosed liquid sampling devices of the invention have provision for flushing and cleaning the collection chamber after each use to avoid contamination of later collected liquid samples by residue from earlier collected samples. In one disclosed embodiment, the inlet means is positioned within an opening in an upper end wall of the collection chamber and is removable to provide cleaning access to the chamber through this opening. In another disclosed embodiment, the upper end wall of the collection chamber is a cover which mounts the inlet means and is removable to provide a large opening through which the chamber may be flushed and cleaned with ease. 
     According to a preferred feature of the invention, certain disclosed embodiments of the invention are provided with means for adjusting the maximum inflow rate of the liquid being sampled into the collection chamber and thereby adjust the maximum sampling duration of the of the sampling device. In these embodiments, the adjustment means is a limit stop for the upper float valve which is adjustable to vary the maximum opening separation of the upper valve from its valve seat. 
     One disclosed embodiment of the invention has an inlet riser through which liquid enters the collection chamber and which rises above the floor of the sampler basin. This riser delays entry of liquid into the collection chamber until the liquid level in the basin rises to the level of the upper end of the riser and is useful for storm water sampling applications. Another disclosed embodiment is time composite sampling device, that is a sampling device for collecting separate consecutive samples of a liquid over a period of time. This sampling device comprises a plurality of separate sample collection chambers and an inlet means for each chamber. These separate inlet means are arranged so that the liquid being sampled fills one collection chamber first, then the next collection chamber, and so on in such a way that the chambers are filled successively at spaced intervals. The preferred composite sampling device of the invention comprises at least two separate collection chambers having inlet risers of different height above the floors of their catch basin(s). 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a liquid sampling device according to this invention located in sampling position; 
     FIG. 2 is an enlarged perspective view, partly in section, of the sampling device in FIG. 1; 
     FIG. 3 is an enlarged partial vertical sectional view of the storm water sampler of FIG. 2, illustrating ball valves embodied in the sampler for sealing the sampler collection chamber against dilution of the collected storm water sample, against entry of foreign objects into the sample collection chamber during periods of non-use, and against escape of volatile elements in the sample; 
     FIG. 4 is a cross-section through a modified liquid sampling device according to the invention for collecting a time composite liquid samples; 
     FIG. 5 is a longitudinal section through a further modified liquid sampling device according to the invention; 
     FIG. 6 is an enlargement of the area encircled by the arrow 6--6 in FIG. 5; 
     FIG. 7 is an exploded perspective view of the sampling device in FIG. 5; 
     FIG. 8 is a view looking in the direction of the arrows on the line 8--8 in FIG. 5; 
     FIGS. 9 and 10 illustrate two alternative sump arrangements for locating the sampling device of FIGS. 5-8 in sampling position; 
     FIG. 11 is an enlarged fragmentary view of the liquid sampling device of FIG. 5; 
     FIG. 12 is a further enlarged axial section through a collection chamber drain valve shown in FIG. 11; 
     FIG. 13 is a longitudinal section through a modified drain valve; and 
     FIG. 14 is a section taken on line 14--14 in FIG. 13. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Turning now to these drawings and first to FIGS. 1-3, there is illustrated a liquid sampling device 10 located in sampling position in the path of a moving liquid S. As mentioned earlier and will be explained in more detail later, a sampling device according to the invention may be utilized to sample a great variety of liquids, including homogeneous liquids and liquid mixtures composed of either miscible or immiscible liquid components, in a variety of sampling environments and for a variety of purposes. Also, the sampling device may be disposed in sampling relation to the sampled liquid in various ways including placement of the device in the path of a moving liquid, as in FIGS. 1-3, and submersion of the device in a body of liquid. 
     A particularly useful and important application of the sampling device involves sampling storm water runoff from an industrial property in accordance with the Storm Water Permitting Program referred to earlier. For convenience, the illustrated sampling device 10 is described primarily in the context of this particular use in which the sampled liquid is the storm water runoff. 
     The illustrated storm water sampler 10 is placed in sampling position within a concrete sump 12 located in the path P of the storm water runoff from the industrial property to be monitored. The sump has an open top covered by a removable grate 14. The sump is located in the storm water flow path P with the grate 14 substantially flush with the surrounding surface along which the storm water flow occurs. A subterranean drain line 16 leads from the bottom of the sump. 
     The storm water sampler 10 comprises a receptacle 18 having a normally lower sample collection chamber 20 and normally upper inlet means 22. This inlet means includes an inlet passage 24 through which storm water can enter the collection chamber. The sampler is positioned in the sump 12 in such a way that sampler inlet means 22 receives storm water entering the sump through the grate 14. At least some of the storm water flows through the inlet passage 24 into the collection chamber 20 until the chamber is filled to a predetermined level, which is the level of FIG. 3. The contents of the chamber then constitutes a storm water sample which can be drained from the chamber through a drain valve 26 at the bottom of the collection chamber and analyzed to determine the presence of contaminants, if any, in the sample picked up by the storm water as it flowed across the industrial property in question. 
     In order to assure an accurate storm water sample which complies fully with the Storm Water Permitting Program, it is neccessary to prevent dilution and contamination of a collected storm water sample by entry of foreign matter into the collection chamber prior to actual storm water sampling during a storm event, by continued storm water flow over the sampling device following collection of a complete storm water sample, and by deliberate action of a person seeking to alter the collected sample. To prevent such dilution and contamination, the sampler inlet means 22 includes inlet valve means 26, 28 which close the inlet passage 24 except when both of the following conditions exist: (a) the upper inlet end of the inlet passage is covered by the liquid to be sampled, and (b) the collection chamber 20 contains less than a predetermined volume of the liquid. This predetermined volume of liquid constitutes a complete storm water sample and occurs when the collection chamber contains storm water to a predetermined level (the level of FIG. 3). The valve means 26, 28 also block escape from the collection chamber of the collected sample liquid and volatile elements present in, that is vapor from, the collected sample. The terms &#34;upper end&#34; and &#34;lower end&#34; as applied herein to the collection chamber are used in a broad sense to mean the top and bottom of the chamber in its normal sampling position regardless of the physical shape of the chamber. 
     Referring now in more detail to FIGS. 1-3, the sampler receptacle 18 comprises a generally cup-shaped body 30 having a cylindrical side wall 32, a bottom wall 34, and an outwardly directed flange or rim 36 about the open, normally upper end of the body. Extending across the interior of the body 30 between its bottom wall 34 and rim 36 is an annular partition wall 38 which is welded or otherwise permanently secured and sealed to the the side wall 32. The space between this partition wall and the bottom wall 34 forms the storm water sample collection chamber 20. 
     The partition wall 38 and the upper end portion of the side wall 32 which extends above the partition wall form a normally upper and upwardly opening storm water catch basin 40 at the upper end of the receptacle 18. The partition wall forms the floor of this basin. The portion of the side wall 32 above this floor forms the side wall of the basin which terminates at its upper end in the rim 36. At the center of the partition wall or basin floor 38 is a circular opening 42 circumferentially surrounded by an upstanding flange 44. Positioned over the upper edge of this flange 44 is resilient seal ring 45 having a coaxial circular slot in its lower edge receiving the flange. 
     Inlet means 22 comprises an inlet fitting 46 removably and coaxially positioned within the basin floor opening 42. This inlet fitting includes, between its ends, an annular plate 48 whose outer edge portion is turned downwardly to form a depending cylindrical flange 50 about the plate. The inner diameter of this flange is sized to fit closely but removably over the seal ring 45. The inner edge portion of the plate 48 is turned upwardly to form an upstanding cylindrical flange 51 about the central opening in the plate. Rigidly joined to and extending coaxially upwardly from the flange 51 is a tubular inlet riser 52 which projects a distance upwardly above the basin floor 38. 
     A strainer 53 of inverted cup shape is positioned over the riser 52. The open bottom of this strainer fits over and is secured to the depending flange 50 on the fitting plate 48. Rigidly joined to and coaxially depending from the underside of the plate is a lower cup-shaped valve cage 54 having ports 56 in its side wall. Fixed to the inside of the strainer 53 over and coaxial with the inlet riser 52 is an upper valve cage 57 of inverted cup shape. 
     The inlet fitting 46 is removably positioned on the partition wall or basin floor 38 with the fitting plate 48 above and seating downwardly against the seal ring 45 and with the plate flange 50 circumferentially surrounding the seal ring. The lower fitting valve cage 54 depends coaxially through the basin floor opening 42 into the collection chamber 20. The inlet fitting is releasably secured in position by connecting means 61 including a shaft 62. Shaft 62 extends upwardly and coaxially through the bottom wall 34 of the collection chamber 20 and is threaded at its upper end in a nut 64 rigidly joined to the bottom wall of the lower valve cage 54. Threaded on the lower end of the shaft, below the bottom wall 34 of the collection chamber 20, are a seal ring 66 and a wing-nut-like grip 68. The shaft is fixed against rotation relative to either the nut 64 or the grip 68, whereby the grip is rotatable to firmly clamp the inlet fitting plate 38 against the seal ring 45 and thereby secure and seal the fitting to the catch basin floor 38 about the floor opening 42. 
     The inlet passage 24 extends longitudinally through and opens through the upper end of the inlet riser 52. The upper end of the riser is located at a level between the upper rim 36 and floor 38 of the basin 40. The lower end of the inlet passage 24 opens to the collection chamber 20 through the valve lower cage 54 and its side wall ports 56. 
     The lower inlet valve means 26 of the storm water sampler comprise a buoyant ball forming a float valve 70 within the lower valve cage 54. This float valve is engagable with a downwardly facing annular valve seat 72 about the lower end of the inlet passage 24. As explained below, the lower float valve 70 normally occupies its lower solid line open position of FIG. 3 wherein the lower float valve is spaced from its valve seat 72. When the lower liquid-receiving space surrounding the lower cage (i.e. collection chamber 20) fills with liquid to the level of the lower cage ports 56, liquid passes from this lower space into the lower cage through the ports 56 and raises the lower float valve 70 to its broken line closed position in which the lower float valve contacts its valve seat 72 to close the lower end of the passage 24. The upper inlet valve means 28 comprises a buoyant valve ball forming a float valve within the upper valve cage 57. This upper float valve is engagable with an upwardly facing annular valve seat 78 about the upper end of the inlet riser 52. The upper float valve 74 is movable through the region above its valve seat 78 (i.e. the region extending upwardly from the seat through the upper valve cage 57). The upper float valve normally occupies its lower solid line closed position of FIG. 3 at the lower end of this region in which the upper float valve engages its valve seat 78 to close the upper end of the passage 24. The upper float valve is movable upwardly through the region and away from its valve seat to its broken line open position of FIG. 3 to open the upper end of the passage 24 when the liquid level in the upper liquid-receiving space surrounding the upper cage and region (i.e. catch basin 40) rises above the upper valve seat 78. The liquid then passes from this upper space into the region above the upper valve seat 78 through the openings in the strainer 53 and the illustrated space between the upper valve seat 78 and the upper valve cage 57 and raises the upper float valve 74 from the upper valve seat. 
     The storm water sampling device 10 is used in this fashion. Prior to the first storm event of the wet season, the sampler is hung in storm water sampling position within the sump 12 located in an anticipated storm water runoff flow path from the industrial property to be monitored, as shown in FIG. 1. Prior to the first storm event, the upper float valve 74 will engage its seat 78 to close the inlet passage 24 against entry of dirt, rocks and other foreign matter into the collection chamber 20. 
     During the first storm event, storm water runoff from the property flows into the sump 12 and enters sampler catch basin 40. When the water level in the basin reaches the upper end of the inlet riser 52, the water raises the upper float valve 74 from its valve seat 78 to an open position within the upper valve cage 76. Storm water then flows from the basin, through the inlet passage 24 into the sampler collection chamber 20. This chamber may have a volume on the order of one gallon. Assuming sufficient rainfall, the collection chamber will eventually fill sufficiently to provide a &#34;grab sample&#34; of the first storm water runoff from the property. As the chamber fills, the lower float valve 70 is raised from its solid line open position of FIG. 3 to its broken line closed position of engagement with its valve seat 72 to close the inlet passage 24. This closure of the lower float valve occurs when the water in the collection chamber 20 reaches a predetermined level (the level shown in FIG. 3) at which the chamber contains a storm water sample of predetermined volume. Closure of the lower float valve prevents dilution and contamination of the collected sample by continuing storm water flow over the sampler or by deliberate action of a person seeking to alter the sample. Closure of the lower float valve also prevents escape of storm water and vapor from the collection chamber. The inlet riser 52 delays flow of storm water from the basin into the collection chamber and acts as a dam which prevents passage of sand, dirt, silt or the like into the collection chamber. 
     When the storm ends or the sampling device is removed from the sump 12, the upper valve ball 74 will reengage its valve seat 78 to seal the upper end of the inlet passage 24 against entry of foreign matter. The sampling device is carried to a laboratory by its illustrated handle, where the collected sample is drained from the collection chamber 20 through the lower drain valve 26 for analysis. The inlet fitting 46 is then removed from the receptacle 18 to permit thorough flushing and cleaning of the fitting and the collection chamber through the basin floor opening 42 to avoid contamination of later collected samples. 
     From the above description, it is evident that the inlet valve means 26, 28 have, in effect, a standby mode in which the upper float valve 74 is closed and the lower float valve 70 is open, a sampling mode in which both float valves are open, and a sample containment mode in which the lower float valve or both float valves is/are closed. The valve means assume the standby mode during storage of the sampling device and when the sampling device is in sampling position awaiting the liquid to be sampled. The valve means assume the sampling mode when the upper inlet end of inlet passage is covered with liquid and the collection chamber contains less than the predetermined volume of liquid neccessary to constitute a complete liquid sample. The valve means assume the sample containment mode when the collection chamber contains a complete liquid sample and the upper float valve is either open or closed. 
     FIG. 4 illustrates a modified storm water sampling device 100 according to the invention for collecting, at spaced intervals, three separate storm water samples which, together, constitue a time composite storm water sample. This composite sampling device comprises, in effect, three separate storm water samplers 102a, 102b, 102c, each essentially identical, except for dimensions, to the storm water sampler of FIGS. 1-3. Accordingly, it is unneccessary to describe each individual composite sampler in elaborate detail. Suffice it to say that the three samplers 102a, 102b, 102c differ from one another and from the sampler in FIGS. 1-3 only in the depth of their upper storm water receiving basins 104 and the height of their inlet risers 106. Thus, the basin depths and riser heights of the three samplers increase progressively. The dimensions and volumes of the sampler collection chambers 108 are equal to one another and to that of FIGS. 1-3. The individual composite samplers are otherwise identical to that of FIGS. 1-3. 
     In use, the storm water time composite sampling device of FIG. 4, is placed in sampling position within an anticipated storm water runoff flow path from an industrial property to be monitored in the same way as described in connection with FIGS. 1-3 so that the storm water enters the upper storm water catch basins 104 of the device. Because of the different basin depths and riser heights of the sampling device, a first storm water sample will be collected in the collection chamber 108 of the sampler 102a with the shallowest basin and lowest riser height. After a period of time determined by the differing basin depths and riser heights, a second storm water sample will be collected in the collection chamber 108 of sampler 102b. After another period of time, a third storm water sample will be collected in the collection chamber of sampler 102c. By properly sizing the individual samplers 102a, 102b, 102c, the time composite sampling device of FIG. 4 may be designed to collect three equal storm water samples at three spaced intervals during a storm event. 
     As mentioned earlier, storm water sampling is but one of the many possible uses to the liquid sampling device of the invention. Another possible use involves sampling of liquid leaking from industrial equipment to aid in locating the source of the leak(s). In this regard, assume that FIG. 1 illustrates the floor of a large industrial facility, such as a brewery, having liquid handling equipment at many locations about the facility and that the liquid S on the floor is from a leak or leaks in this equipment which cannot be located by direct inspection. Assume further that the processes performed in the equipment are such that the composition of the leakage liquid will be determined, at least to some extent, by the location of the leak(s) in the equipment. Accordingly, analysis of the leakage liquid will aid in locating the source of the leak(s). 
     The liquid sampling device of this invention may be used to collect samples of the leakage liquid for analysis and thereby aid in locating the leaks. In FIG. 1, for example, the liquid sampling device 10 of the invention may be placed in sampling position within a sump 12 in the floor of the facility to sample leakage liquid S flowing along the floor. Sampling operation of sampling device in this application, of course, is exactly the same as described earlier in connection with storm water sampling. Other uses of the sampling device are also possible. In some cases, a liquid sample might be collected by submerging the sampling device in a body of the liquid. In other cases, the sampling device might be located to sample liquid flowing through a pipe or other fluid conductor or to sample liquid effluent from such a liquid conductor. 
     Referring now to FIGS. 5-7, the illustrated liquid sampling device 200 comprises an outer casing 202 having an open upper end, and a liquid sampler 204 proper positioned in casing 202 and removable from the casing through its upper end. The casing 202 has a cylindrical side wall 206, a bottom wall 208, and an annular shoulder 210 extending circumferentially about the upper end of the side wall and terminating along its radially outer edge in an upstanding cylindrical wall portion 212. The upper edge of this wall portion turns outwardly to form a lip or rim 214. 
     The liquid sampler 204 is very similar in construction and operation to the sampler of FIGS. 1-3. The sampler 204 includes a generally cup-shaped cylindrical receptacle 216 having an open upper end, a cylindrical side wall 218, and a bottom wall 220. The upper end portion of the side wall 218 turns outwardly to form an annular flange 222 and an upwardly opening annular seat for an O-ring seal 224 circumferentially surrounding the open upper end of the receptacle. Coaxially disposed below the bottom wall 220 of the receptacle 216 is a base 226 of inverted cup-shape for supporting the sampler 204 when it is removed from the casing 202. The base has a top wall 227 seating against and rigidly joined to the bottom wall 220 of the sampler receptacle 216, a sidewall opening 228 whose purpose will be explained presently, and a lower flange 230. 
     The sampler 204 is sized in diameter and length to fit closely but removably within the casing 202 with the sampler flange 222 seating on the casing shoulder 210 to vertically support the sampler in the casing. In this supported postion, the bottom flange 228 of the sampler base 226 is spaced from the bottom wall 208 of the casing, as shown in FIG. 5. When the sampler is removed from the casing, the base is used to support the sampler in an upright position on a supporting surface. 
     The open upper end of the sampler receptacle 216 is closed by a removable partition wall or cover 232 having a shallow cup-shaped body 233. The cover has an annular bottom wall 234 and a cylindrical side wall 236 projecting upwardly from the edge of the bottom wall. About the upper end of the cover side wall 236 is an outwardly directed annular flange 238. The cover 232 is removably positioned in the upper end of the receptacle 216 with the cover body 233 fitting closely but removably within the upper end of the receptacle and with the cover flange 238 resting on the upper receptacle flange 222 to vertically support the cover in the receptacle. The O-ring 224 provides a liquid seal between the cover and the upper end of the receptacle. 
     The interior space of the receptacle 216 between the cover 232 and the bottom wall 220 of the receptacle forms a liquid collection chamber 240. The cover and the upper side wall portion 212 of the receptacle form an upwardly opening liquid catch basin 242 above the collection chamber. The cover forms the floor of this basin. The upper receptacle side wall portion 212 forms the side wall of the basin which terminates at its upper end in the rim 214. The center of the cover wall 234 has a shallow coaxial circular recess 243 containing a relatively large coaxial circular opening 244 circumferentially surrounded by a depending flange 246. 
     Positioned on the cover 232 within the cover recess 243 and opening 244 are liquid inlet means 248 similar to the inlet means of the liquid sampling device in FIGS. 1-3. As shown best in FIG. 6, the inlet means 248 comprises an inlet fitting 250 including an upper float valve cage 252, a lower float valve cage 254, and a strainer 256 about the upper valve cage. The upper valve cage 252 includes a tube 258 having a multiplicity of flow openings in its wall and closed at its lower end by an integral coaxial circular wall or plate 260. This plate projects radially beyond the tube to form a coaxial circular flange about the lower end of the tube. Extending through the plate 260 coaxial with the tube 258 is an inlet passage 262 surrounded by a depending short cylindrical sleeve 264 depending from the plate. The lower end of this sleeve flares outwardly to form a downwardly facing lower valve seat 266 about the lower end of the passage 262. About the upper end of the passage 262 is an upwardly facing upper valve seat 268. 
     The lower valve cage 254 comprises a sleeve 270 having a multiplicity of flow openings in its wall and an annular flange 272 about its upper open end. Fixed within the lower end of the sleeve 270 is an internally threaded nut 274. The upper flange 272 of the lower cage 254 seats against and is rigidly joined to the underside of the upper cage plate 260 with the two cage sleeves 258, 270 coaxially aligned. 
     The strainer 256 of the inlet fitting 250 has an inverted cup shape. The lower edge of the strainer is rigidly joined to the outer edge of the upper valve cage plate 260, as by crimping the strainer edge over the plate edge, as shown. Fixed in the upper end of the strainer is a disc 276 which fits within the upper end of the upper cage sleeve 258. 
     Freely movable within the upper and lower valve cages 252, 254 are ball float valves 278, 280, respectively, which form, with the upper and lower valve seats 268, 266, upper and lower inlet valve means 282, 284. The upper float valve 278 is movable downwardly to its closed position of FIGS. 5 and 6 against the upper valve seat 268 to close the inlet passage 262. The upper float valve is movable upwardly away from the upper valve seat to an open position against an adjustable limit stop 286 to open the inlet passage. The limit stop 286 is threaded in the strainer disc 276 for adjustment toward and away from the upper valve seat 268 to adjust the maximum open flow area of the upper valve means 282. The lower float valve 280 is movable downwardly to its open position of FIGS. 5 and 6 away from the lower valve seat 266 to open the inlet passage 262, and upwardly to its closed position against the lower valve seat to close the inlet passage. 
     The sampler receptacle 216, cover 232, and inlet means 248 are releasably joined in assembled relation by connecting means 288. As best shown in FIG. 11, this connecting means comprises a rod 290 threaded at its upper end in the nut 274 of the lower valve cage 254. The lower end of the rod 290 is enlarged and defines a threaded axial socket for connection to a drain valve 292 located within the sampler base 226. Drain valve 292 has an L-shaped body 294, one arm of which (the vertical arm in FIG. 12) is threadedly joined to a threaded stem 296. This stem extends axially upward through the bottom wall 220 of the receptacle 216 and the top wall 227 of the base 226 and is threaded in the lower end of the connecting rod 290. About the base of the stem 296 is a shoulder supporting a seal ring 298 engaging the upper base wall 227. 
     The drain valve 292 is rotatable in one direction about the axis of the connecting rod 290 to tighten the connecting means 288 for firmly securing the sampler receptacle, cover, and inlet means in assembled, mutually sealed relation. The drain valve is rotatable in the opposite direction to release the connecting means 288 for disassembly of the sampler for cleaning, as illustrated in FIG. 7. Fixed to the cover 232 are handles 299 for holding the sampler and placing the sampler in and removing it from the casing 206. 
     Threaded in the remaining horizontal arm of the drain valve body 294 is a drain tube 300 having an external knurled portion 302 by which the tube may be rotated. On the outer end of the drain tube is a hose nipple 304 for connection to a drain hose 306 extending through the base sidewall opening 228. The drain valve contains a passage 308 which extends at one end through the vertical arm of the valve body 294 and the threaded stem 296, and opens into the sampler collection chamber 240 through ports 310 in the stem. The other end of the valve passage 308 extends axially through the horizontal arm of the valve body 294, the drain tube 300 and the hose nipple 304. On the inner end of the drain tube 300 is a valve head 312. This valve head is movable axially into and from engagement with a valve seat 314 about the valve passage 308 by rotation of the drain tube to open and close the passage. 
     FIGS. 9 and 10 illustrate two different ways of locating the sampling device 200 in sampling position for the storm water sampling or leak sampling applications mentioned earlier. In FIG. 9, the sampler casing 202 of the sampling device is embedded in concrete at the bottom of a relatively deep sump 316 with the lip 214 of the casing flush with the bottom of the sump. The sump is covered by a grate 318 flush with ground level and has a drain line 320 leading from the bottom of the sump. In FIG. 10, the casing 202 is embedded in concrete with the upper casing lip 214 flush with the bottom of a shallow cavity 322 covered by a grate 324 flush with ground level. 
     The sampling device 200 is used in essentially the same way as the sampling device 10 of FIGS. 1-3 except for the following differences. In FIGS. 1-3, the upper float valve seat 78 is located at upper end of the inlet riser 52. When the liquid level in the basin 40 rises above the level of the upper valve seat, the upper float valve is raised from the seat to permit liquid flow into the inlet riser and then through the riser into the collection chamber 20. In the sampling device 200, the lowest flow openings in the side wall of the upper valve cage 258 are located a distance above the floor 234 of the basin 242, and the solid lower portion of the cage below these lowest openings forms an inlet riser 325. The upper valve seat 268 is located at the bottom of this inlet riser. Accordingly, when the liquid level in the basin 242 reaches the upper end of the inlet riser 325, the liquid flows over and to the bottom of the riser and then raises the upper float valve 278 from the upper valve seat 268 to permit flow into the collection chamber. The inlet riser serves the same purposes as the inlet riser in the sampling device 10. 
     The maximum flow opening of the upper float valve means 282 is adjustable by adjustment of the limit stop 286. This upper valve adjustment adjusts the maximum liquid flow rate from the basin 242 into the collection chamber 240 and thereby the overall sampling duration of the sampling device. As a consequence, the limit stop adjustment permits use of the sampling device 200 for time composite storm water sampling. The inlet means 248 of the sampling device 200 also has a vent tube 326 which extends upwardly from the cover wall 234, laterally into the upper valve cage 258, and then downwardly toward the cover wall and contains a vent passage for venting air from the top of the collection chamber 240 to atmosphere during filling of the chamber with liquid. 
     After the desired liquid sample has been collected, the sampler 204 is removed from the casing 202 by its handles 299 and carried to a laboratory where the sample is drained from the sampler through the drain valve 292 for analysis. After each use, the sampler is disassembled and thoroughly cleaned. In this regard, t will be seen that removal of the cover 232 from the sampler receptacle 202 provides a large opening in the upper end of the receptacle through which the interior of the collection chamber 240 may be easily cleaned. 
     FIGS. 13 and 14 illustrate an in-line drain valve 400 for use on the liquid sampling device 200 in place of the right angle drain valve 292. The in-line valve includes an elongate drain bolt 402 having an upper threaded end for threaded connection with the lower end of the connecting rod 290 of the sampling device 200. The lower end of the drain bolt 402 is radially enlarged to form a coaxial shoulder portion 404. Axially entering the lower end of this shoulder portion is an internally threaded socket 406 which continues in a smaller diameter bore 408 extending axially upward through a lower end portion of the drain bolt. Threaded in the socket 406 is an internally threaded bushing 410 which forms a valve seat 411 about the lower end of the bore 408. The drain bolt 402 contains two axially spaced pairs of ports 412 opening to the bore along mutually perpendicular axes. 
     Threaded in the bushing 412 is a drain tube 414. This drain tube has a lower threaded portion, an upper valve head 418, and an intervening circumferential recess 420. The valve head 418 is slightly larger in diameter than the threaded bore in the bushing 412. Threaded on and rigidly fixed to the lower end of the drain tube is a knurled grip 422 from which a hose nipple 424 extends axially of the tube. Extending axially through the drain tube 414, the grip 422, and the nipple 424 is a passage 426 which opens radially into the upper drain tube recess 420 through ports 428 in the bottom of the recess. 
     The drain valve 400 is installed on the liquid sampling device 200, in place of the right angle drain valve 292, by inserting the drain bolt 402 through the bottom wall 220 of the device and threading the upper end of the bolt into the lower end of the connecting rod 290 to firmly join the sampler receptacle 216, cover 232, and inlet means 248 in the same manner as described earlier in connection with the sampling device 200. 
     The drain valve 400 is closed by rotating the grip 422 in a direction to move the tube downwardly until its valve head 418 engages the bushing valve seat 411. In this closed position, the drain tube ports 428 are situated below the valve seat 411 so that liquid cannot enter the drain valve passage 426 from the collection chamber 240. The drain valve is opened by rotating the drain tube in the opposite direction to move its valve head 418 upwardly from the valve seat 411 to a position in which the drain tube recess 420 opens radially outward to either the lower pair of drain bolt ports 412 only or to both pairs of these ports. Liquid flow can then occur from the sampler collection chamber 240 through the lower drain bolt ports 412 and the drain tube ports 428 into the drain valve passage 426. Operation of the liquid sampling device 200 with the drain valve 400 is the same as with drain valve 292. 
     It is evident at this point that the inlet valve means, i.e. the two valve balls together with their valve seats and cages, embodied in each described embodiment of the invention constitutes an inlet float valve means which closes the liquid inlet passage to the sample collection chamber except when both of the following conditions exist: (a) the inlet of the inlet passage is submerged in the liquid being sampled, and (b) the sample collection chamber contains less than a predetermined liquid volume. This inlet float valve means has an open mode in which the inlet valve opens the inlet passage to permit liquid flow into the collection chamber and a closed mode in which the inlet valve closes the inlet passage to seal the chamber and is operable to each of these modes by forces including a buoyant force produced by the liquid being sampled, i.e. by gravitational and buoyant forces.