US3822597A

US3822597A - Method and apparatus for sampling liquids

Info

Publication number: US3822597A
Application number: US00311920A
Authority: US
Inventors: J Clark
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-12-04
Filing date: 1972-12-04
Publication date: 1974-07-09
Anticipated expiration: 1991-07-09

Abstract

A method and apparatus is described for extracting periodically a sample of a liquid corresponding to a predetermined fraction of the whole flowing past the sampling location, with means to raise the sample to a higher level, means to discharge the sample into a container whose contents will correspond to the total volume of the stream that has flowed past that location during a known past interval, with simple means to cause the sample extractor to clear itself continually from any required slime or garbage that otherwise would affect the accuracy of the volume or the continuity of the samples taken.

Description

United States Patent [191' Clark METHOD AND APPARATUS FOR SAMPLING LIQUIDS [76] Inventor: James dA. Clark, Chuckanut Point,

Bellingham, Wash. 98225 [58} Field of Search 73/421 B, 423 R, 425.4 R; 222/148, 216, 217

[56] References Cited UNITED STATES PATENTS 1,603,712 10/1926 Peck 73/421.5 R 2,2705] 1 1/1942 Crain 73/423 R 3,715,058 2/1973 Clymans 22/148 FOREIGN PATENTS OR APPLICATIONS 1,160,218 12/1963 Germany 73/421 B [111 3,822,597 [451 Jul 9,1974

Primary Examiner-S. Clement Swisher ABSTRACT A method and apparatus is described for extracting periodically a sample of a liquid corresponding to a predetermined fraction of the whole flowing past the sampling location, with means to raise the sample to a higher level, means to discharge: the sample into a container whose contents will correspond to the total volume of the stream that has flowed past that location during a known past interval, with simple means to cause the sample extractor to clear itself continually from any required slime or garbage that otherwise would affect the accuracy of the volume or the continuity of the samples taken.

10 Claims, 8 Drawing Figures PATENTED SHEET 2 BF 3 9L iii MAXIMUM FLOW LEVEL ZERFFLOW LEVEL FIG-2 FIG-3 PATENIEML men I 1 y/ /d SHEET 3 OF 3 MAX/MUM FLOW LEVEL ZERO FIG 5 FLOW/LEVEL 24 2? Fla-"6 SUMMARY OF THE INVENTION A sampling apparatus is provided in accordance with the method having a shaft with the lowest portion cut away and so shaped that when enclosed with a sleeve, forms a cavity that contains a liquid sample whose volume, when the shaft is immersed in the stream at a fixed elevation, bears a constant ratio to the volume of thestream flowing past that location at that time. The required contour of the cut-away portion of the shaft has been described in my US. Pat. No. 2,164,498 of July 3, 1939. Subsequently, several variations of the disclosed design, but employing the same principle, have been in general use. However, in any situation where the stream being sampled contains slimeforming matter or solids that cling to the surfaces, such as raw sewage, the volume of the cavity will'be decreased or even entirely filled with such matter, thereby impairing the accuracy of the sampling.

To overcome this deficiency, a novel device is employed continually to keep the cavity clear. In the preferred design, mechanism is provided to lower the sleeve and projecting sampling shaft with its cut-away,

vertically into the stream to be sampled, until the lower end of the cut-away reaches a fixed elevation, usually tha't elevation at which the stream ceases to flow. Further downward movement of the lowering mechanism causes a scraperattached to the lower end of the sleeve to traverse the effective surface of the cut-away and remove any accumulated solid material therefrom. Con

currently a sample of theliquid flows into the newly cleared. cavity formed by the cut-away and the descending sleeve. The sleeve is further lowered a little way until its lower edge forms a seal against the lower end of the shaft, thus locking the sample in place.

The closed, sealed assembly and liquid is then raised above a sample collector where a projection on the shaftcauses the collector to assume a position directly beneath the assembly. Continued upward movement causes a stop to halt the shaft, but permits thesleeve to continue rising. This opens the cavity, allowing the liquid sample therein to fall into the collector. Further upward movement of the sleeve continues until the lower edge of the scraper is at the top of the effective length of the cut-away. Governed by a timer, the assembly then again descends, first causing the collector to move out of its way, then it continues to descend until the cut-away reaches its lower fixed elevation, when the sampling cycle recommences- In another design particularly adapted to sampling streams far below the surface, the shaftis held fixed with its cut-away in the stream at its proper location. Only the sleeve is moved up and down far enough to clear the cut-away, permit entry of the sample, and then to seal it within the cut-away. The enclosed sample is then raised by compressed air to the sample collector and discharged therein.

Some of the forms of the apparatus suitable forcarrying out this invention are shown diagrammatically in the drawings in which:

FIG. 1 is an elevation of a form of an installation, with collector directed into a sample receiver,

FIG. 2 is a fragmentary side elevational view of a sleeve and shaft, with its cut-away extending completely across the shaft, shown extending downwards from the sleeve,

FIG. 3 is a partial front elevation, similar to FIG. 2 bu having a cut-away consisting of a slot cut into the shaft,

FIG. d shows a fragmentary side elevational view of FIG. 3 as the cavity formed by the cut-away and sleeve is about to be enclosed,

FIG. 5 shows a fragmentary sectional view of an alternative form of seal for the sample cavity,

FIG. 6 is a fragmentary side elevation of an installation especially suitable for locations where the sample has to be raised to a substantial hieght for collection, by employing compressed air; I

FIG. 7 is a fragmentary view of the collector actuator situated so as to position the collector away from the rising or descending shaft end,

FIG. 8 is as FIG. 7 with the activator moved such that the collector is in position to receive the sample.

DETAILED DESCRIPTION As shown in the figures, the sample taker is in the form of a shaft T1 with cut-away 12 over which the sleeve 13 slides. In FIG. I the sampling shaft 11 and sleeve 13 are raised and lowered by a rack and pinion 14 operated by an electric motor with conventional limit and timing switches (not shown). Alternatively the raising and lowering may be accomplished by other means such as a cylinder and piston actuated by cornpressed air or water controlledby a timing valve. With either driving mechanism, means are provided such as the rack or a key that slides in a slot 15 is a fixed bearing so as to prevent the assembly from rotating.

In FIG. 1, the assembly has reached its highest position, prior to which pin 16 (see also FIG. 2 and 3) in its upward movment has contacted the upper projection of the actuator link 17 (see also FIGS. 7 and 8) and tipped trough 18 into position to receive any liquid enclosed by sleeve 13 in the cut-away 12. Upon further upward movement, the pin 16 comes against a stop 19 which prevents further upward movement of the shaft 1 l. The spring detent 20 on the sleeve disengages itself from the pin 16 as the sleeve moves further upwards, thereby uncovering the bottom of the cut-away l2 and so permitting its contents to fall into trough l8 and flow into the sample container 21. Sleeve 13 continues still further upwards until the cut-away 12 is almost wholly exposed and with the lower end of the spring cleaning blade 22 near the top of the cut-away as shown also in FIGS. 2 and 3.

After a predetermined period controlled by a timer, the assembly starts downward, the pin 16 actuates link 17 to cause the trough 18 to resume a vertical rest position out of the way of the descending assembly. The assembly continues downwards until the shaft is stopped, for example by pin 16 contacting stop 43 as shown in FIGS. 1 and 2. The shaft is thereby positioned at alevel so that the bottom of the cut-away 12 is at the level at which the stream ceases to flow, or if the level of the stream will not drop below this, such that the cut-away holds a fixed quantity of liquid corresponding to the flow of the stream at that particular level. The sleeve 13 continues to descend as the close fitting lower end of the spring blade 22 attached to it, moves down through the cut-away 12 as shown in FIGS. '1, 2 or 5,

or the slotted cut-away 12a in FIGS. 3 and 4, and cleans off any sediment that may have become attached to the surfaces. The type of seal shown in FIGS. 1, 2, 3 and 4 comprises a flat round rubber-like gasket 23 and the blade is provided with a tongue attachment 24, shown in FIGS. 2, 3, 4 and 6 which contacts the bevelled side of,'or a cam on, the washer 25 that holds the gasket 23 in place, and raises the tip of the doctor blade 22 before it reaches the gasket, thereby avoiding any damage to the gasket.

The bottom inside rim of the sleeve 13 contacts the periphery of the gasket 23 to make a perfect seal for the liquid that meanwhile has flowed into the cut-away. Just prior to this seal being made, pin 16 slips into the curve of spring detent 20 which keeps the seal firmly closed while the assembly is subsequently raised to discharge the enclosed sample into the container as described above.

It will be obvious that the apparatus as described can be modified in several respects without departing from the spirit of this invention. For example, in place of the tipping trough l8 and associated linkages as shown in FIG. 1, a chain attached to the assembly or mechanism actuated by a limit switch may be employed to place means to receive the enclosed sample under the bottom end of the assembly before the seal is broken as described, and subsequently to withdraw the receiver before the assembly descends to take another sample.

Also, a similarly actuated moveable scraper may be pushed into position to traverse the cut-away on the exposed shaft as the assembly descends. This scraper may take the form of a rotary brush with its periphery moving downwards at a speed slightly faster than the descending shaft. However, the material cleaned off would make the surroundings of the apparatus more clamp and more messy. Consequently it is desirable to simplify the cleaning mechanism as much as possible and to provide that this cleaning operation is accomplished within the stream, with the further advantage that the cut-away is simultaneously washed, any accumulation of dirt being there carried away by the stream.

Also contemplated is an alternative form of seal as shown in FIG. 5, comprising an elastic band 26 attached to and extending downwards from the lower end of sleeve 13, enabling it to effect a seal against the lower-cylindrical surface or the rim of the shaft 11. In some applications, this modification might be satisfactory if the sealing band could be frequently renewed, since it would be prone to gather abrasive particles that would wear both it and the shaft. The band would also cause additional friction to the sliding movement between the sleeve and shaft.

Especially if the stream to be sampled is at a considerable depth below the surface, this invention may be practised by a modified means of raising the sample as for example is shown in F IG; 6. Here at the bottom of the cut-away 12 is a rotary plug valve 26 with its conventional pressure adjusting screw and lock nut. When valve 26 is closed, part of its outer face forms part of the lower inner face of the cut-away 12. When the valve is rotated slightly by moving the linkage 27 and arm 28 fixed to the top of rigid pipe 29, as by a piston and-cylinder, a passage is opened as shown, from the bottom of the cut-away to up through the pipe 29 to the sample container 21a. In this modification the shaft 11 with cut-away 12, is shortened and is held rigidly at a fixed elevation by a projection 30 attached to a stationary support 31, preferably at a location above the surface of the stream. In this arrangement, the slideable sleeve I13 is connected by linkage 32 to the piston and cylinder 33 controlled by three-way valves ll and 42 timed to open at intervals so as to raise and lower the sleeve 13 about fixed shaft II. This could also be accomplished by an arm attached to the shaft of a gear motor arranged to make periodic single revolutions. Connected to the top of the cut-away I2 is a pipe 35 passing upwards to a solenoid valve 36 in a compressed-air supply line 37. Using a sequence timer to operate the

valves

36, 41 and 42 and plug valve 26 by any well known means, a sample is taken as follows:

Starting with the sleeve 13 in its lowest position, but with valves 26 to the cut-away and 36 to the compressed-air supply closed, motor 34 makes a single revolution to raise the sleeve so that the bottom edge of the doctor blade 22 rises above the effective part of the cut-away 112, then descends with its scraper 22 to clear off the cut-away and. further descends to effect a seal around the bottom of shaft 11. Meanwhile, a sample of the stream corresponding to its level has flowed into the cut-away. After the seal has been effected, valve 26 is opened to the cut-away as shown in FIG. 6 followed by a brief opening of valve 36 to blow the sample out of the cut-away, up pipe 29 into the container 21a. Valve 26 is then closed, followed immediately by closing air valve 36 after its brief opening. After a fixed predetermined interval, the sampling cycle is repeated as just described. To prevent possible blockage of the inlet to the rotary valve 26, it is desirable to connect the bottom of cut-away 12 to the horizontal passage in valve 26 by means of a narrow vertical slot 38 in shaft 11.'To ensure that this slot does not become plugged it is further desirable to connect pipe 29 by means of a flexible hose 39 to a valve 40 leading to the compressed air supply. When valve 36 is opened to elevate the liquid in the cut-away, valve 40 is opened simultaneously to a small extent so as to prevent any of the sample being discharged from lodging in the hose 39.

Subsequently, when the sleeve 13 is raised and prior to its descent, valve 40 is fully opened. This serves to direct a high speed stream of compressed air down pipe 20 and through slot 38 so as to remove any material therein.

Finally, with certain types of liquid particularly those containing a detergent in the stream to be sampled, it is possible to dispense with the scraper 22 and instead arrange the timer to open valve 36 when the sleeve is, or is being, raised and effectively scour the surfaces of the cut-away 12 with a blast of compressed air from pipe 35.

In certain installations it maybe more expedient to arrange to take a fixed volume of the sample but at varying intervals, such intervals being controlled inversely by the height of the stream. This may be effected by any well known means such as a float actuated by the height of the stream moving an electrical contact over an adjoining series of resistors controlling the amount of current flowing to a heater requiring a certain amount of electrical energy to operate a thermo-electric relay switch that functions to start the sampling operation and thus control the periods between which the samples are taken so as to be substantially in accordance with the level and corresponding volume of the flowing stream.

I claim:

l. The method of taking a sample of liquid from a stream in accordance with its volumetric flow, comprising immersing a member having a vertically elongated exposed recess whose volume of contained liquid when enclosed, bears a fixed ratio to the volume of the stream flowing at the time of sampling, and at fixed periodic intervals simultaneously cleaning off the surface of the recess and enclosing a sample therein, then raising and discharging the sample for analysis.

2. The method of taking a sample of liquid from a stream in accordance with its volumetric flow, comprising immersing a member having a recess which when enclosed contains a fixed predetermined volume of liquid simultaneously cleaning off the surface of the re cess and entrapping the sample of liquid therein, raising and discharging the sample for analysis and reimmersing the member in the stream to take another sample at intervals whose duration corresponds inversely with the rate of flow of the stream. f 3. Apparatus for taking a sample of liquid froma stream comprising a shaft and sleeve with the side of the shaft cut-away so that then it is immersed in the stream at a fixed elevation and subsequently covered with the sleeve, it contains a predetermined volume of liquid, positioning the shaft at a predetermined fixed elevation in the stream, cleaning means to traverse and thereby remove any material attached to the surface of the cut-away, means to seal the enclosed sample of liquid between the cut-away and the sleeve, and means to raise and discharge the enclosed sample into a container for analysis.

4. Apparatus in accordance with claim 3 said cleaning means comprising a cleaning blade projecting from the lower end of said sleeve with its lower edge bearing on the surface of the cut-away portion of the shaft such that when the sleeve is pushed down to cover the lower end of said shaft said blade traverses the surface of the cut-away thereby removing any extraneous'matter adhering thereto and means subsequently to effect a seal between the shaft and the bottom of the sleeve whereby the volume of liquid contained in the cut-away may be raised intact.

5. Apparatus in accordance with claim 4 having means for sealing the sample in place in the recess in the shaft, comprising a gasket with a diameter slightly larger than that of the inside of the sleeve and fixed to the bottom of the shaft with a cover piece, means to protect the edge of the gasket from being damaged by the lower edge of the cleaning blade as it passes down- .wards over the gasket at that point, and a detent firmly to hold the lower inner edge of the sleeve against the faced the gasket when it has engaged therewith.

6. Apparatus in accordance with claim 5 with the means to protect the edge of the gasketcomprising a rigid extension projecting outwards and downwards from the lower edge of said scraping blade said extension engaging with a sloped surface on said cover piece thereby lifting the blade away from the edge of the gasket before the edge of the blade reaches it.

7. Apparatus in accordance with claim 3 wherein the means for conveying the sample to the container comprises a conduit whose upper edge can swing clear of the path of the shaft and sleeve as they move upward and links actuated by a projection from the shaft and sleeve assembly to swing the upper end of the conduit beneath the assembly when it has moved above the conduit, thus enabling the conduit to catch the sample when the seal between the sleeve and shaft is broken as the sleeve moves further upwards and the shaft is retained and means to swing the end of the conduit away from the path of the assembly when it has commenced to move downwards.

8. Apparatus for taking a sample from a liquid stream comprising a fixed shaft with a recess to receive the sample, situated in the stream and a snug fitting vertically slideable sleeve on the lower portion of the shaft, means adapted to traverse and clean said recess, means to slide the sleeve down to enclose and finally seal a sample in the recess, an exit valve at the bottom of the shaft which, when opened, connects the bottom of the recess through a discharge pipe to an elevated sample collector, a tube connected to the top of the recess leading to a valve and compressed air supply and a timing and actuating mechanism to cause the sleeve to slide down, clean the recess, entrap a sample, then to open the exit valve, open the compressed air supply valve, thereby raising the sample enclosed in the recess to the sample collector, close the exit valve, close the compressed air valve and, when a predetermined period has elapsed, raise the sleeve: to its upper position ready to recommence the sampling cycle.

9. Apparatus in accordance with claim 8 with means to blow for a short period compressed air down through said discharge pipe to the elevated sample collector when said sleeve is raised and prior to closing the said exit valve so as to clean any material in the passage from said recess to said pipe.

10. Apparatus in accordance with claim 9 in which the short passage between said recess and the inlet to the-exit valve, consists of a narrow vertical slot serving as a screen whereby the passage of material large enough to clog the :alvf 0; said pipe is prevented.

Claims

1. The method of taking a sample of liquid from a stream in accordance with its volumetric flow, comprising immersing a member having a vertically elongated exposed recess whose volume of contained liquid when enclosed, bears a fixed ratio to the volume of the stream flowing at the time of sampling, and at fixed periodic intervals simultaneously cleaning off the surface of the recess and enclosing a sample therein, then raising and discharging the sample for analysis.

2. The method of taking a sample of liquid from a stream in accordance with its volumetric flow, comprising immersing a member having a recess which when enclosed contains a fixed predetermined volume of liquid simultaneously cleaning off the surface of the recess and entrapping the sample of liquid therein, raising and discharging the sample for analysis and reimmersing the member in the stream to take another sample at intervals whose duration corresponds inversely with the rate of flow of the stream.

3. Apparatus for taking a sample of liquid from a stream comprising a shaft and sleeve with the side of the shaft cut-away so that then it is immersed in the stream at a fixed elevation and subsequently covered with the sleeve, it contains a predetermined volume of liquid, positioning the shaft at a predetermined fixed elevation in the stream, cleaning means to traverse and thereby remove any material attaChed to the surface of the cut-away, means to seal the enclosed sample of liquid between the cut-away and the sleeve, and means to raise and discharge the enclosed sample into a container for analysis.

4. Apparatus in accordance with claim 3 said cleaning means comprising a cleaning blade projecting from the lower end of said sleeve with its lower edge bearing on the surface of the cut-away portion of the shaft such that when the sleeve is pushed down to cover the lower end of said shaft said blade traverses the surface of the cut-away thereby removing any extraneous matter adhering thereto and means subsequently to effect a seal between the shaft and the bottom of the sleeve whereby the volume of liquid contained in the cut-away may be raised intact.

5. Apparatus in accordance with claim 4 having means for sealing the sample in place in the recess in the shaft, comprising a gasket with a diameter slightly larger than that of the inside of the sleeve and fixed to the bottom of the shaft with a cover piece, means to protect the edge of the gasket from being damaged by the lower edge of the cleaning blade as it passes downwards over the gasket at that point, and a detent firmly to hold the lower inner edge of the sleeve against the face of the gasket when it has engaged therewith.

6. Apparatus in accordance with claim 5 with the means to protect the edge of the gasket comprising a rigid extension projecting outwards and downwards from the lower edge of said scraping blade said extension engaging with a sloped surface on said cover piece thereby lifting the blade away from the edge of the gasket before the edge of the blade reaches it.

8. Apparatus for taking a sample from a liquid stream comprising a fixed shaft with a recess to receive the sample, situated in the stream and a snug fitting vertically slideable sleeve on the lower portion of the shaft, means adapted to traverse and clean said recess, means to slide the sleeve down to enclose and finally seal a sample in the recess, an exit valve at the bottom of the shaft which, when opened, connects the bottom of the recess through a discharge pipe to an elevated sample collector, a tube connected to the top of the recess leading to a valve and compressed air supply and a timing and actuating mechanism to cause the sleeve to slide down, clean the recess, entrap a sample, then to open the exit valve, open the compressed air supply valve, thereby raising the sample enclosed in the recess to the sample collector, close the exit valve, close the compressed air valve and, when a predetermined period has elapsed, raise the sleeve to its upper position ready to recommence the sampling cycle.

10. Apparatus in accordance with claim 9 in which the short passage between said recess and the inlet to the exit valve, consists of a narrow vertical slot serving as a screen whereby the passage of material large enough to clog the valve or said pipe is prevented.