US3750477A

US3750477A - Liquid sampling

Info

Publication number: US3750477A
Application number: US00214822A
Authority: US
Inventors: M Rutkowski; R Thompson
Original assignee: Pro-Tech Inc
Current assignee: Pro-Tech Inc
Priority date: 1972-01-04
Filing date: 1972-01-04
Publication date: 1973-08-07
Anticipated expiration: 1990-08-07

Abstract

Samples are taken from a body of liquid at intervals by converting continuous flow of fluid from a pressurized source into intermittent sample-propelling flow. Both the repetition frequency of sampling and the duration of individual samplings is controlled through regulation of the propellant flow rate. Principal uses are in stream monitoring for pollution control, sewage treatment facilities, and industrial waste reduction programs.

Description

United States Patent 1 Rutkowski et a1.

LIQUID SAMPLING Inventors: Michael D. Rutkowskl, Phocnixvillcl Richard R. Thompson, West Chester, bothof Pa.

Assignee: Pro-Tech, lnc., Malvern, Pa.

Filed: Jan. 4, 1972 Appl. No.: 214,822

11.8. C1. 73/421 B, 417/145 Int. Cl. G0ln 1/14 Field of Search 73/421 B; 417/143,

References Cited UNITED STATES PATENTS 2/1964 Snyder 73/421 B 10/1930 Simmons 417/146 1' Aug. 7, 1973 2,026,226 12/1935 Entrop 417/143 R14,946 9/1920 Aikmun ..4l7/i45 FOREIGN PATENTS OR APPLICATIONS 570,475 1/1924 France 147/143 Primary Examiner-S. Clement Swisher Attorney-Charles A. McClure et al.

[57] ABSTRACT Samples are taken from a body of liquid at intervals by converting continuous flow of fluid from a pressurized source into intermittent sample-propelling flow. Both the repetition frequency of sampling and the duration of individual samplings is controlled through regulation of the propellant flow rate. Principal uses are in stream monitoring for pollution control, sewage treatment facilities, and industrial waste reduction programs.

12 Claims, 8 Drawing Figures PATENTEDws 1 ms 750,477 saw 1 or 3 vm mm PATENTEU AUG 7 I975 SHEET 3 [IF 3 LIQUID SAMPLING This invention relates to sampling a liquid medium, such as for determination of the composition thereof or of contaminants therein, concerning especially such sampling accomplished by use of a pressurized fluid for sample propulsion.

Manual techniques for sampling a medium for analysis or related purposes are giving way to automatic sampling, usually electrically operated. Devices for setting frequency of sampling include spring-driven and electrical timing devices. Electrical operation is hazardous in an explosive atmosphere, such as may-be encountered in oil refineries and other industrial operations, in sewers and sewage treatment plants, and in pollutionridden areas. Electrical power lines are not available at remote sampling sites, and batteries often are cumbersome or otherwise unsatisfactory. Spring-winding is inconvenient, and spring motors are a source of maintenance requirements.

A primary object of the present invention is provision of a system for fluid-energized sampling of liquids;

Another object is flow-regulated control of sampling frequency and duration.

A further object is accomplishment of the foregoing objects by means of relatively simple apparatus.

Other objects of this invention, together with means and methods for attaining the various objects, willbe apparent from the following description and the accompanying diagrams of a preferred embodiment thereof, which is presented by way of example rather than limitation.

FIG.. 1 is a schematic representation of a liquidsampling'system of the present invention.

FIG. 2a is a side sectional elevation of pressureresponsive switching valve mechanism useful according to this invention; and

FIG. 2b is a fragmentary side sectional elevation of the mechanism of the preceding view in an alternative position.

FIG. 3a is a fragmentary side sectional elevation, on an enlarged scale, of the same mechanism in the same position as in FIG. 2a; and

FIG. 3b is a like view of the same mechanism in the same position as in FIG. 2b.

FIG. 4a is a schematic representation of the valve position corresponding to that of FIGS. 2a and 3a;

FIG. 4b is a like representation of the alternative valve position of FIGS. 2b and 3b; and

FIG. 5 is an exploded perspective view of a sampling chamber useful according to the invention.

In general, the objects of the present invention are accomplished, in sampling of liquid from a body thereof at a given locus therein to a collection location, by providing a source of propellant fluid under pressure, regulating a continuous rate of flow of such fluid from the source, converting the continuous fluid flow to intermittent flow between the source and the sampling locus, and propelling successive samples thereby from the body of liquid to the collection location with a certain repetition frequency by intcrmittentinterconnection of the source thereto.

In particular, the invention extends to apparatus for sampling liquid repeatedly from a body thereof, com prising a source of fluid at superatmospheric pressure, first valve means therebetween for determining the sampling repetition rate, including a first normally closed pressure-responsive switching valve; second valve means for determining the duration of individual samplings, including a second normally closed pressure-responsive switching valve therebetween; and conduit means leading from the fluid source to the body of fluid and containing the respective valvev means.

FIG. 1 shows schematically that source 10 of fluid under pressure has main conduit 11 leading therefrom past various branches and valves to sampling chamber 16, which is immersed in a body of liquid to be sampled. Valves in the main conduit include first normally open pressure-regulating valve V which ensures a first level of constant pressure immediately downstream therefrom; normally closed pressure-responsive switching valve V which is adapted to open at a given pressure; and second normally open pressure-regulating valve V which (when valve V is open) ensures a second, lower level of constant pressure immediately downstream therefrom, where the sampling chamber is located.

Ancillary branch conduit 13 leads from junction with main conduit 1 1 at a location between valves V and V and rejoins the main conduit between valve V and the sampling chamber. Adjustable first flow-regulating valve V which is normally at least partially open, is located in the initial part of the ancillary conduit. The ancillary conduit itself has branch line 12a to primary surge tank 12, and pressure line 13a (shown with arrowhead) to the pressure-sensitive part of valve V Downstream from that branching, ancillary conduit 13 contains second normally closed pressure-responsive switching valve V before rejoining the'main conduit.

Auxiliary conduit 15 (not to be confused with the ancillary conduit) leaves main conduit 11 at a location downstream from valve V andupstream from valve V It goes to the pressure-sensitive part of valve V through adjustable second flow-regulating valve V which is normally at least partly open. Branch line I4a leads from the auxiliary conduit to secondary surge tank 14, and branch line 15a (with arrowhead) extends from the same junction to the sensing part of valve V Sample conduit 17 leads from the sampling chamber to collection vessel 18, which has vent 19 to the atmosphere. Also vented to the atmosphere in the normally closed position of pressure-responsive switching valve V via its vent 13b is sampling chamber 16 connected thereto by the intervening portion of main conduit 11.

FIG. 2a shows, in side sectional elevation, normally closed pressure-responsive switching valve mechanism 20 suitable for use as valve V and FIG. 2b shows fragmentarily the valve portion thereof in the alternative open position. FIGS. 3a and 3b show fragmentarily on an enlarged scale the switching portion of the same valve'mechanism in the closed and open positions, respectively. FIGS. 4a and 4h show schematically the normally closed (and vented) position and the alternative open position of the valve portion thereof. Valve V is similar except for lack of a corresponding vent.

As shown in FIG. 20, valve mechanism 20 comprises housing 21 for the switching portion and housing 23 for the valve portion, respectively, joined by sleeve 22. At the right end of rightmost housing 21 is sensing inlet 24 for pressurized fluid. First free piston 25, which has cireumferential seal 26 fitting slidably along the inside wall of the housing against shoulder 27 at the end, has a largely flat face toward the inlet and recess 28 in its opposite face. Enlarged end 32 of the push rod 33 fits within the recess in the piston face. At the other end of the housing, second free piston 35, which has a flat face toward the first piston, has an axial bore through which stem 29 of the push rod extends.

Compression spring 31 between the two pistons bears at its one end against the flat face of second piston 35. The opposite face of the second piston is dished by conical recess 38 and at its peripheral extent normally bears against the adjacent inside end wall of housing 21. Balls 36 are retained in the recess and normally intrude partway into double tapered neck portion 39 of push rod 33. Adjacent end 37 of the push rod protrudes through a central opening in the near end wall of housing 21 and a matching opening in the adjacent end wall of housing 23.

Valve mechanism 20 contains in housing 23 a threeway valve (30, see FIGS. 4a and 4b) comprising pair of

interior walls

40 and 50 axially bored to receive axially extending valve member 45, whose opposite ends 41 and 49 fit slidably within

cylindrical guides

42 and 48 affixed to the opposite inside end walls. Valve seats 44 and 46 on the sides of respective

interior walls

40 and 50 face the adjacent end walls and accommodate respective valve faces 54 and 56 on

enlarged portions

53 and 57, respectively, of the valve body. Compression spring 59 fits about cylindrical guide 48 and end 49 of the-valve member and bears at its one end against the adjacent inside end wall of the housing and at its opposite end against enlarged portion 57 of the valve member.

Rightmost compartment 52 of housing 23 has outlet 62 to vent 301; through. the housing wall thereinto, and normally communicates with central compartment 55 via the opening between valve face 54 and seat 44 on interior wall 40 and the bore therethrough. Central compartment 55 and leftmost compartment 58 have respective outlet 65 and inlet 68 through the housing walls. The compartments are normally noncommunicating by reason of the seating of valve face 56 on seat 46. Upstream line 30a connects to inlet 68, and downstream line 30c joins outlet 65.

FIGS. 3a and 3h show, respectively, on an enlarged scale the normally closed and normally open switching positions of the valve mechanism shown in the preceding views. FIGS. 4a and 4]) show the corresponding valve positions schematically, together with respective upstream and

downstream lines

30a and 30c and vent 30b in conjunction therewith. In the normally closed position the downstream line and the vent are interconnected, and the upstream line is blocked, as in FIG. 2a. In the alternative, open position the upstream and downstream line are interconnected, and the vent is blocked, as in FIG. 2b.

FIG. shows sampling chamber 16 in more detail. Bottom cap 61, which threads at its reduced upper end into the bottom end of cylindrical chamber body 72, has openings therethrough to admit some of the surrounding medium to the chamber interior. Top cap 63, which has fitting 66 for main conduit 11 and fitting 67 for sample conduit 17 aligned with bores (not visible) therethrough, threads at its reduced lower end into the top end of chamber body 72. Toroidal gaskets or 0- rings 64a, 64!) are located at the top and bottom ends to seal the sampling chamber when the caps are threaded into the respective ends of the body.

Located just above bottom cap 6] of sampling chamber 16 is check valve assembly V which comprises seat member 71, cage mounted thereon, and ball 77 secured in the cage by transverse pin 79 at the top end. The top face of the seat member is counterbored to accommodate the lower end of the cage, which is press-fit thereinto, and seat 80 is centrally located at the base of the counterbored portion. The seat member has sample intake bore 73 axially therethrough and has peripherally indented top edge 74. Lower O-ring 64b fits about that edge and against internal shoulder 78 in the chamber body (shown partly cut away to reveal the interior). Extending downward into the chamber body from the top cap and fitting 67 is dip tube 70, which terminates alongside cage 75 of the check valve when the sample chamber is assembled.

Operation of the liquid-sampling system of this invention, as embodied in the illustrated apparatus, is readily understood. Fluid from source 10 at elevated pressure flows through valve V and enters the main and ancillary conduits at a first given level of pressure determined by the valve. The fluid cannot pass through normally closed valve V but flows, at a rate determined by the setting of V into primary surge tank 12, where it accumulates at gradually increasing pressure, which is transmitted also to the pressure-sensitive actuating (i.e., switching) part of valve V The fluid cannot pass through normally closed valve V downstream in the ancillary conduit.

When the pressure in the ancillary conduit and surge tank reaches the switching pressure of valve V that valve opens, connecting the fluid source to the sampling chamber through valve V which reduces the pressure to a lower given level. Fluidat the latter pressure flows into the sampling chamber, closing check valve V and forcing the contents through the sample conduit toward the collection vessel and possibly into it.

In the meantime, after opening of valve V fluid from the source has begun to flow through valve V,at a rate determined by its setting and downstream back pressure, and into secondary surge tank 14 and contact with the pressure-sensitive actuating or switching part of valve V When the switching pressure of the latter valve is reached, after a delay period determined by the setting of valve V and resulting pressurization of secondary surge tank 14, valve V, opens and thereby connects primary surge tank 12 to the sampling chamber. If the sample (i.e., the former contents of the sampling chamber) is already in the collection vessel this extra flow will purge the sampling chamber, sample conduit, and collection vessel and will exhaust to the atmosphere through vent 19; if the sample has not yet reached the collection vessel it will beboosted thereinto by this surge of fluid, with like resulting purging action.

When the pressure in the ancillary conduit falls sufficiently, as the primary surge tank loses pressure, valve V; will switch back to its closed position, after which the secondary surge tank will lose pressure upon occurrence of reverse flow through valve V, and through vent [3b of valve V, (or downstream through valve V Thereupon valve V, will close, liquid will reenter the sampling chamber through check valve V and displace propellant fluid through that vent, and the cycle will recommence.

It is apparent, therefore, that the sampling duration or flow of propellant fluid into and through the sampling chamber, is controlled principally by the setting of valve V Similarly, the sampling frequency or repetition rate is controlled chiefly by the setting of valve V Of course, variation in the sampling duration varies the sampling frequency (with valve V, at a fixed setting) but is normally relatively limited. The sampling repetition rate usually is within the range of from about a half minute to a couple hours, while the sampling duration usually ranges between several seconds and about 10, seconds or so. The duration, together with the pressure settings and surge tank sizes and related factors (e.g., conduit size and length) determine the height to which the sample may be lifted, which usually ranges from a few feet upwards of about a hundred feet.

Usually the medium sampled is aqueous, whether from natural streams, water supplies, sewage systems, or industrial effluents. However, it may be nonaqueous, such as oil, gasoline, or other organic liquid. The propellant fluid should be selected as suitably inert to the liquid being sampled; some such gases may be supplied in liquefied form in a source vessel Examples of propellant fluid include nitrogen, carbon dioxide, halogenated hydrocarbon, or even compressed air (if oxygenation of the sample is not important). Suitable fluids are sold, chiefly for refrigerant use, under such brand names as Freon" (a duPont trademark) and lsotron (a Pennwalt trademark).

The dimensions of the apparatus are dependent upon the nature of the sampled medium, including the concentration, nature, and size of any solids therein. The materials of construction should be suitably inert, of course, with regard to the medium to be sampled. Ordinarily the sampling apparatus can be made portable to permit its ready transportation to and from almost any sampling site.

Effective sampling is a prerequisite to analysis and/or treatment of the medium in question, such as for pollution control. Good regulation of sampling frequency is required in the formation of composite samples. The apparatus of this invention permits a wide range of sampling frequency with accurate and ready regulation thereof. The first pressure-regulating valve assures that propellant fluid is supplied to the rest of the system at essentially constant pressure regardless of temperature variation (above condensation temperature for the fluid) and thereby assures dependable repetition frequencies. No electricity or conventional mechanical power source is required, and the explosion hazard usually associated with electrical activation is eliminated.

Whereas a particular apparatus embodiment and certain modifications therein have been described, other modifications may be made, as by addition, combination, or division of parts or steps, or by substitution of equivalents therefor, while retaining at least some of the advantages and benefits of the invention, which itself is defined in the following claims.

We, claim:

I. In apparatus for sampling liquid from a body thereof, at the instance of a propellant fluid supplied from a source under pressure; the combination of conduit means comprising a main conduit for conducting such fluid to a sampling locus in the body of liquid, an ancillary conduit branching therefrom in the vicinity of the propellant source means and rejoining the main conduit in the vicinity of the sampling locus, and an auxiliary conduit also branching from the main conduit; valve means comprising a first normally closed pressure-responsive switching valve located in the main conduit and having actuating means responsive to fluid pressure in the ancillary conduit, :1 first normally open pressure-regulating valve in the main conduit between the source means and the first pressure-responsive switching valve means, and a first normally open flowregulating valve in the ancillary conduit; and accumulating means comprising a first surge tank connected to the ancillary conduit intermediate the first flowregulating valve means and the actuating means of the first pressure-responsive switching valve.

2. Liquid-sampling apparatus according to claim 7, wherein the valve means includes a second normally open pressure-regulating valve in the main conduit between the first pressure-responsive switching valve and the sampling locus and effective to limit the downstream fluid pressure to a lower level than that established by the first such valve.

3. Liquid-sampling apparatus according to claim 2, including a sampling chamber interconnected to the end of the main conduit, a normally open check valve between the sampling chamber and the body of liquid,

a remote collection vessel, and conduit means interconnecting the sampling chamber to the collection vessel.

4. Apparatus for sampling liquid repeatedly from a body thereof for operation by fluid from a source thereof at superatmospheric pressure, comprising first valve means therebetween for determining the sampling repetition rate, including a first normally closed pressure-responsive switching valve; second valve means therebetween for determining the duration of individual samplings, including a second normally closed pressure-responsive switching valve; and conduit means leading from the fluid source to the body of fluid and containing the respective valve means, wherein the conduit means includes a main conduit leading from the fluid source to the first normally closed pressure-responsive valve and on to the body of liquid, and an ancillary conduit leading from a junction with the main conduit to a pressure-sensing part of that first valve and to the second normally closed pressureresponsive'switching valve and on to rejoin the main conduit immediately upstream from the body of liquid, and the first valve means includes a flow-regulating valve in the ancillary conduit.

5. Liquid-sampling apparatus according to claim 11, wherein the conduit means includes also an auxiliary conduit leading from a junction with the main conduit immediately downstream from the first pressureresponsive valve to a pressure-sensing part of the second pressure-responsive valve, and the second valve means includes a flow-regulating delay valve in the auxiliary conduit.

6. Liquidsampling apparatus according to claim 4, wherein the first valve means includes a regulating valve between the source of pressurized fluid and the junction of the ancillary conduit with the main conduit.

7. Liquidsampling apparatus according to claim 5 wherein the main conduit includes a regulating valve between the junction with the auxiliary conduit and the body of fluid.

8. Liquid-sampling apparatus according to claim 1 wherein the valve means includes a second normally closed pressure-responsive switching valve located in the ancillary conduit and having actuating means responsive to fluid pressure in the auxiliary conduit and a second normally open flow-regulating valve in the auxiliary conduit.

9. Liquid-sampling apparatus according to claim 8 wherein the accumulating means includes a second surge tank interconnected to the auxiliary conduit intermediate the second flow-regulating valve and the actuating means of the second pressure-responsive switching valve.

10. Liquid-sampling apparatus according to claim 7, wherein the first pressure-responsive valve in the normally closed position has a normally open vent to the main conduit downstream therefrom.

ll. Pressure-operated apparatus for sampling liquid repeatedly from a sample chamber in a body thereof at the instance of fluid from a source thereof at superatmospheric presssure, comprising first valve means therebetween for determining the sampling repetition rate, second valve means therebetween for determining the duration of individual samplings, conduit means for interconnecting the valve means to such fluid source and sample chamber and including a main conduit, an ancillary conduit, and an auxiliary conduit; the valve means including a first normally closed pressureresponsive switching valve located in the main conduit and having actuating means responsive to fluid pressure in the ancillary conduit, a second normally closed pressure-responsive switching valve located in the ancillary conduit and having actuating means responsive to fluid pressure in the auxillary conduit, a first flowregulating valve located in the ancillary conduit and a second flow-regulating valve located in the auxiliary conduit for controlling the sampling repetition rate and the duration of individual samplings, respectively; the main and ancillary conduits joining one another upstream of the respective valves, and the main and auxiliary conduits joining one another downstream of the first valve.

12. Liquid-sampling apparatus according to claim 11 including a first surge tank located in the ancillary conduit downstream of the first flow-regulating valve, and a second surge tank located in the auxiliary conduit downstream from the second flow-regulating valve.

*0 t l t l

Claims

1. In apparatus for sampling liquid from a body thereof, at the instance of a propellant fluid supplied from a source under pressure; the combination of conduit means comprising a main conduit for conducting such fluid to a sampling locus in the body of liquid, an ancillary conduit branching therefrom in the vicinity of the propellant source means and rejoining the main conduit in the vicinity of the sampling locus, and an auxiliary conduit also branching from the main conduit; valve means comprising a first normally closed pressure-responsive switching valve located in the main conduit and having actuating means responsive to fluid pressure in the ancillary conduit, a first normally open pressure-regulating valve in the main conduit between the source means and the first pressure-responsive switching valve means, and a first normally open flow-regulating valve in the ancillary conduit; and accumulating means comprising a first surge tank connected to the ancillary conduit intermediate the first flow-regulating valve means and the actuating means of the first pressure-responsive switching valve.

3. Liquid-sampling apparatus according to claim 2, including a sampling chamber interconnected to the end of the main conduit, a normally open check valve between the sampling chamber and the body of liquid, a remote collection vessel, and conduit means interconnecting the sampling chamber to the collection vessel.

4. Apparatus for sampling liquid repeateDly from a body thereof for operation by fluid from a source thereof at superatmospheric pressure, comprising first valve means therebetween for determining the sampling repetition rate, including a first normally closed pressure-responsive switching valve; second valve means therebetween for determining the duration of individual samplings, including a second normally closed pressure-responsive switching valve; and conduit means leading from the fluid source to the body of fluid and containing the respective valve means, wherein the conduit means includes a main conduit leading from the fluid source to the first normally closed pressure-responsive valve and on to the body of liquid, and an ancillary conduit leading from a junction with the main conduit to a pressure-sensing part of that first valve and to the second normally closed pressure-responsive switching valve and on to rejoin the main conduit immediately upstream from the body of liquid, and the first valve means includes a flow-regulating valve in the ancillary conduit.

5. Liquid-sampling apparatus according to claim 4, wherein the conduit means includes also an auxiliary conduit leading from a junction with the main conduit immediately downstream from the first pressure-responsive valve to a pressure-sensing part of the second pressure-responsive valve, and the second valve means includes a flow-regulating delay valve in the auxiliary conduit.

6. Liquid-sampling apparatus according to claim 4, wherein the first valve means includes a regulating valve between the source of pressurized fluid and the junction of the ancillary conduit with the main conduit.

7. Liquid-sampling apparatus according to claim 5 wherein the main conduit includes a regulating valve between the junction with the auxiliary conduit and the body of fluid.

11. Pressure-operated apparatus for sampling liquid repeatedly from a sample chamber in a body thereof at the instance of fluid from a source thereof at superatmospheric presssure, comprising first valve means therebetween for determining the sampling repetition rate, second valve means therebetween for determining the duration of individual samplings, conduit means for interconnecting the valve means to such fluid source and sample chamber and including a main conduit, an ancillary conduit, and an auxiliary conduit; the valve means including a first normally closed pressure-responsive switching valve located in the main conduit and having actuating means responsive to fluid pressure in the ancillary conduit, a second normally closed pressure-responsive switching valve located in the ancillary conduit and having actuating means responsive to fluid pressure in the auxillary conduit, a first flow-regulating valve located in the ancillary conduit and a second flow-regulating valve located in the auxiliary conduit for controlling the sampling repetition rate and the duration of individual samplings, respectively; the main and ancillary conduits joining one another upstream of the respective valves, and the main and auxiliary conduits joining one another downstream of the first valve.