US3751983A - Liquid sampling - Google Patents

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 are 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 1 Rutkowski et a1.

[ LIQUID SAMPLING [75] Inventors: Michael D. Rutkowski, Phoenixville;

Richard R. Thompson, West Chester, both of Pa.

[73] Assignee: Pro-Tech, Inc., Malvem, Pa.

[22] Filed: Mar. 23, 1972 [211 App]. No.: 237,400

\ Related US. Application Data [63] Continuation-impart of Ser. No.,2l4,822, Jan. 4,

[52] US. Cl. 73/421 B, 417/145 [51] Int. Cl. GOln 1/14 [58] Field of Search 73/421 B; 417/143,

[56] References Cited UNITED STATES PATENTS 2/1964 Snyder 73/421 B 11] 3,751,983 [451 Aug. 14, 1973 1,779,252 10/1930 Simmons 417/146 2,026,226 12/1935 Entrop 417/143 1214,946 9/1920 Aikman 417/145 Primary ExaminerS. Clement Swisher Att0rneyCharles 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 are 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.

6 Claims, 8 Drawing Figures PAIENTEB AUG 1 4 i975 SHEU 1 BF 3 PATENIED AUG 1 4 I915 SHEET 3 0f 3 l LIQUID SAMPLING.

This application is a continuation-in-part of our similarly entitled copending application, Ser. No. 214,822 filed 4 Jan. 1972.

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, of maintenance requirements, especially in corrosive atmospheres. and spring motors are a source 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, will be apparent from the following description and the accompanying diagrams of 'a preferred embodimentthereof, 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

prising a source of fluid at superatmospheric pressure, first valve means therebetween for determining the sampling repetition rate substantially independently of the source pressure, including a first normally closed pressure-responsive switching valve; second valve means for determining the duration of individual samplings, including a second normally closed pressureresponsive switching valve therebetween; and conduit means leading from the fluid source to the body of fluid and containing the respective valve means.

FIG. 1 shows schematically source 10 of propulsion fluid under pressure and 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 levelof constant pressure immediately downstream therefrom; first normally closed pressureresponsive switching valve V which is adapted to-open at a given pressure; and throttling valve V,,, which (when valve V is open) somewhat reduces the pressure immediately downstream therefrom, where the sampling chamber is located.

Ancillary branch conduit 13 leads from junction with main conduit 11 at a location between valves V and V Second constant-pressure regulator valve V and I adjustable first flow-regulating valve V which is nor- FIG. 2b is a fragmentary side sectional elevation of the mechanism of the 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 30;

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 continuous flow of propellant fluid from a source thereof under pressure, regulating such flow substantially independently of the source pressure, intermittently interconnecting the source and the sampling locus in accordance 'with the flow of such fluid from the source to a first accumulation location, and thereby propelling successive samples thereby from the body of liquid to the collection location with a certain repetition frequency.

In particular, the invention extends to apparatus for sampling liquid repeatedly from a body thereof, compreceding view in an alternative mally at least partially openfare located in series in the initial part of the ancillary conduit. Sensing line of valve V leads thereto from a junction with conduit 13 downstreamof valve V thus effectively paralleling the latter valve so as to maintain a substantially constant pressure drop across it and, thus, a substantially. constant flow rate therethrough in accordance with the setting thereof. 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, ancillaryconduit 13 contains second normally closed pressureresponsive switching valve V which in its open position dumps the primary surge tank to the atmosphere via outlet 13d downstream.

Auxiliary conduit 15 (not to be confused with the ancillary conduit) leaves main conduit 11 at a location downstream from valve V and upstream 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 14a 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 interveningportion 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 showsfragmentarily 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 4b 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, or suitable plugging thereof.

As shown in FIG. 2a, valve mechanism comprises housing 21 for the switching portion and housing 23 for the valve portion, respectively, jointed by sleeve 22. At the right end of rightmost housing 21 is sensing inlet 24 for pressurized fluid. First free piston 25, which has circumferential 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 30b 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 300 joins outlet 65.

FIGS. 3a and 3b 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 4b '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. 5 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, 64b 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 61 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 therethroughand 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 pressure determined by valve V and 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 somewhat. Fluid at the latter pressure flows into the sampling chamber, closing check valve V, and forcing the contents through the sample conduit toward and into the collection vessel.

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 dumps primary surge tank 12 to the atmosphere.

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 13b 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 several hours, while the sampling duration usually ranges between several seconds and about seconds or so. The duration, together with the pressure settings and surge tank sizes and related factors (e.g., conduit size and length) determine th 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 liquified 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 Fr-eon" (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 second pressure-regulating valve assures that propellant fluid is supplied to that portion of the system at essentially constant pressure, regardless of source pressure or intentional changes in the setting of the first pressure-regulating valve, so as to accommodate a wide range of sample lifts, and thereby enhances linearity of action and assures dependable repetition frequencies. More economical use of propulsion fluid renders it unnecessary for the primary surge tank to be connected to the sampling chamber. 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 has been described, it will be understood that variations may be made, as in the interest of manufacturing economy. Thus, upon utilizing an auxiliary conduit of sufficient volume the secondary surge tank becomes superfluous. Other modifications also may be made therein, 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: 1. Apparatus for sampling liquid repeatedly from a body thereof for operation by a source of fluid at supe ratmospheric pressure, comprising first valve means therebetween for determining the sampling repetition rate substantially independently of the source pressure, including a first normally closed pressure-responsive switching valve; second valve therebetween means 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 pressuresensing part of that first valve and on to the second normally closed pressure-responsive switching valve, and the first valve means includes a pressure-regulating valve and a flow-regulating valve in series in the ancillary conduit, the pressure-regulating valve having a sensing line leading thereto from the ancillary conduit immediately downstream of the flow-regulating valve.

2. Liquid-sampling apparatus according to claim 1, wherein the conduit means includes also an auxiliary conduit leading from a junction with the main conduit immediately downstream from the first pressureresponsive switching valve to a pressure-sensing part of the second pressure-responsive switching valve, and the second such valve means includes a flow-regulating delay valve in the auxiliary conduit, and the main conduit downstream therefrom includes a throttling valve.

3. Liquid-sampling apparatus according to claim 1, wherein the first valve means includes flow-regulating means between the source of pressurized fluid and the junction of the ancillary conduit with the main conduit.

4. Liquid-sampling apparatus according to claim 2, wherein the main conduit includes a regulating valve between the junction with the auxiliary conduit and the body of fluid.

5. 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 pressure, 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 auxiliary 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 auxiliary conduit opening to the atmosphere downstream of the first valve.

6. Liquid-sampling apparatus according to claim 5, including a first surge tank located in the ancillary con duit downstream of the first flow-regulating valve, and a second surge tank located in the auxiliary conduit downstream from the second flow-regulating valve.

Claims (6)

1. Apparatus for sampling liquid repeatedly from a body thereof for operation by a source of fluid at superatmospheric pressure, comprising first valve means therebetween for determining the sampling repetition rate substantially independently of the source pressure, including a first normally closed pressureresponsive switching valve; second valve therebetween means 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 on to the second normally closed pressure-responsive switching valve, and the first valve means includes a pressureregulating valve and a flow-regulating valve in series in the ancillary conduit, the pressure-regulating vAlve having a sensing line leading thereto from the ancillary conduit immediately downstream of the flow-regulating valve.

2. Liquid-sampling apparatus according to claim 1, wherein the conduit means includes also an auxiliary conduit leading from a junction with the main conduit immediately downstream from the first pressure-responsive switching valve to a pressure-sensing part of the second pressure-responsive switching valve, and the second such valve means includes a flow-regulating delay valve in the auxiliary conduit, and the main conduit downstream therefrom includes a throttling valve.

3. Liquid-sampling apparatus according to claim 1, wherein the first valve means includes flow-regulating means between the source of pressurized fluid and the junction of the ancillary conduit with the main conduit.

4. Liquid-sampling apparatus according to claim 2, wherein the main conduit includes a regulating valve between the junction with the auxiliary conduit and the body of fluid.

5. 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 pressure, 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 auxiliary 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 auxiliary conduit opening to the atmosphere downstream of the first valve.

6. Liquid-sampling apparatus according to claim 5, 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.

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