US3533295A - Sample valve - Google Patents

Description

Oct. 13, 1970 Filed Dec. 50, 1968 D M. VESPER SAMPLE VALVE 5 Sheets-Sheet l 5 POWER GAS SAMPLE 20 I3 200 26 CARRIERI nu I30 VP VENT 24 4c: PILOT VALVE I 20 Zlc: I 27 I '4 VENT Z l PROGRAMMER WCHROMATOGRAPHIC COLUMN DETECTOR F/G.

INVENTOR.

D. M. VESFER A 7' TORNEVS D. M. VESPER SAMPLE VALVE Oct. 13, 1970 5 Sheets Sheet 2 Filed Dec. 30, 1968 FIG. 2

INVENTOR.

D. M.VESPER QM Q m ATTORNEYS United States Patent 3,533,295 SAMPLE VALVE Daniel M. Vesper, Bartlesville, Okla, assignor to Phillips Petroleum Company, a corporation of Delaware Filed Dec. 30, 1968, Ser. No. 787,773 Int. Cl. G01n l/JO US. Cl. 73-422 Claims ABSTRACT OF THE DISCLOSURE A sample valve comprises a valve body having a member secured thereto through which a plurality of passages extend. Pressure operated actuating means are carried by the valve body to block communication between ends of the passages. A detachable valve cap, having passages therethrough, is secured to the member so that passages in the cap and member are in communication. External conduits can be connected to the passages in the cap to communicate through such passages with passages in the member.

It is common practice to analyze fluid mixtures by means of chromatography. In a conventional chromatographic analyzer, a sample of the material to be analyzed is introduced into a chromatographic column, and carrier gas is thereafter passed through the column to elute the constituents of the sample in sequence. In order to ob tain reproducible results, it is important that the sample volumes introduced into the column remain constant. This can be accomplished by means of sample valves which trap a predetermined volume of the sample in a loop and deliver this trapped volume to the column when the valve is actuated. A member of pneumatically operated diaphragm valves have been designed which are particularly effective for this purpose. One such valve is described in U.S. Pat. 3,140,615.

The valve described in the foregoing patent, which is typical of pneumatically operated sample valves, is usually provided with at least eight conduits through which carrier gas, sample and power gas flow. Although such a valve is quite effective and reliable, it is sometimes difiicult to remove the valve from the analyzer for cleaning and repair purposes. This results from the fact that the analyzers are normally assembled in temperature controlled housings of compact design and it is necessary to break the eight conduit connections.

In accordance with the present invention, an improved pneumatically operated sample valve is provided which can readily be removed from a chromatographic analyzer. This is accomplished by means of a single inlet fluid distribution cap which receives all of the external conduits. The valve body is secured to this distribution cap by any convenient means, such as a plurality of screws, so that the valve body can be removed from the connecting conduits merely by removing the valve body from the distribution cap. A replacement valve can then be attached and the analyzer returned to service while the initial valve is being cleaned or repaired. This structure greatly simplifies maintenance of chromatographic analyzers.

In the drawing, FIG. 1 is a schematic representation of a chromatographic analyzer having the sample valve of this invention incorporated therein. FIG. 2 is a view, shown partially in section, of the sample valve employed in the analyzer of FIG. 1. FIG. 3 illustrates the fluid distribution cap of the sample valve. FIG. 4 illustrates the manifold of the valve of FIG. 2. FIG. 5 is a perspective view illustrating a portion of the valve mechanism. FIG. 6 is a view, shown partially in section, of the fluid distribution cap of FIG. 3.

Referring now to the drawing in detail and to FIG. 1 in particular, there is shown a chromatographic column ice 10 which contains any suitable packing or partitioning material. Carrier fluid is introduced through a conduit 11 which communicates with the first inlet port 11a of a sample valve 12. A sample of fluid to be analyzed is introduced through a conduit 13 which communicates with an inlet port 13a of sample valve 12. A conduit 14 extends from sample valve port 1411 to the inlet of column 10. A conduit 15 extends from the outlet of column 10 to the first inlet of a differential detector 16. A portion of the carrier fluid is passed through a conduit 17 to the second inlet of detector 16.

Sample valve 12 is employed to introduce a predetermined volume of sample selectively to the inlet of column 10. This is accomplished by means of a sample loop 20 which extends between ports 20a and 20a in such a manner that the sample initially flows through the loop to fill the interior thereof. After flowing through loop 20, the sample is vented through a conduit 21 which communicates with port 21a. Initially, carrier fluid flows from conduit 11 through valve 12 to conduit 14 and from there through column 10. When the valve is actuated, the flow of carrier fluid is diverted within the valve so as to pass through loop 20 before entering outlet conduit 14. At the same time, the flow of sample is vented. This results in the carrier fluid forcing the volume of sample which originally occupied the loop out through conduit 14 to column 10. Sample valve 12 is pneumatically operated and receives operating pressure from a pilot valve 22. Power gas is introduced into valve 22 through an inlet conduit 23. A conduit 24 extends between the pilot valve and the sample valve. A conduit 25 extends between a vacuum pump 26 and sample valve 12 to facilitate operation of the sample valve under certain conditions, as described hereinafter in greater detail. The operation of the sample valve can be controlled by a programmer 27 which actuates pilot valve 22 at predetermined intervals.

Sample valve 12 is illustrated in detail in FIGS. 2 to 5. All of the external conduits illustrated in FIG. 1 enter a common fluid distribution cap 30. As illustrated in FIGS. 2 and 3, this cap is provided with eight inlet ports. The first six of these ports 11a, 13a, 20a, 20a, 21a and 14a receive corresponding conduits of FIG. 1, as previously described. Ports 24a and 25a receive respective conduits 24 and 25. Cap 30 is attached by screws 31 to a member 32. The first six ports of cap 30 are connected to respective internal passages in the cap (designated by corresponding b reference numerals) which terminate at the lower face of the cap in a circular array. Member 32 is provided with six vertical passages 11c, 13c, 20c, 20c, 21c and which are aligned with corresponding passages in cap 30. O-rings 33 are positioned in recesses in the upper face of member 32 to provide fluid tight seals between the connected passages. Member 32 is also provided with two outlet ports 24d and 25d which communicate with respective inlet ports 24a and 25a. This communication is established by passages 24b and 25b in cap 30 and passages 24c and 250 in member 32. External conduits 24c and 252 serve to connect ports 24d and 25d with respective inlet openings 24 and 25f in a cylindrical housing member 34 of the sample valve.

As illustrated in FIG. 2, the valve includes an upper plate 35 which is secured to manifold 32 by a plurality of set screws 36. First and second diaphragms 37 and 38 are positioned between the lower face of member 32 and the upper face of plate 35. A sealing ring 39 surrounds the diaphragms. Plate 35 is secured to a sleeve 40 by means of a screw 41, and a lower plate 42 is secured to sleeve 40 by means of a screw 43. Cylindrical housing member 34 extends between plates 35 and 42. Pistons 45 and 46 are disposed within housing 34 and are provided with respective sliding sealing members 47 and 48 which engage the inner wall of housing 34.

A plurality of spring washers 49 are positioned between plate 42 and piston 45 to urge the piston upwardly. The upper surface of piston 45 is adapted to engage three plungers 50, 51 and 52, see FIG. 5, when piston 45 is moved upwardly. Piston 46 carries an annular member 53 which is adapted to engage plungers 54, 55 and 56 when member 53 is moved upwardly. A spring 57 is secured to plate 35 by a screw 58 so as to exert a downward force on piston 46. A plurality of pins 59, 60 and 61 extend through common passages in plate 35, member 32 and cap to provide alignment of these three members when the valve is assembled.

As illustrated in FIG. 5, plate is provided with six vertical passages through which plungers 50, 51, 52, 54, 55 and 56 are free to move. Plungers 5'4, 55 and 56 are slightly longer than plungers 50, 51 and 52. The upper surface of plate 35 is provided with a plurality of recesses 63 which connect the ends of adjacent vertical passages through the plate. Recesses 63 permit fluid flow between the lower ends of adjacent passages in member 32 when the diaphragms are depressed into these recesses. The movement of the diaphragms into the recesses is con trolled by plungers 50, 51, 52, 54, 55 and 56. The upper end of plunger 50 is located between passages 21c and 20c; the upper end of plunger 54 is located between passages 13c and 21c; the upper end of plunger 51 is located between passages 20c and 130; the upper end of plunger 7 55 is located between passages 11c and 200; the upper end of plunger 52 is located between passages 11c and 140; and the upper end of plunger 56 is located between passages 20c and 14c. The raising and lowering of the plungers thus controls communication between adjacent passages in member 32.

In the absence of power gas flowing to chamber 65 of FIG. 2, the valve is in the position illustrated. Washers 49 exert an upward force on piston 45, the upper surface of which engages longer plungers 54, 55 and 56 so that the sections of the diaphragm engaged by upper ends of these plungers are moved to block respective recesses 63. Under this condition, the passages through member 32 are connected in the manner illustrated by the solid lines in FIG. 1. Carrier gas flows from conduit 11 to conduit 14 and into column 10. The sample fluid flows through loop 20 and is vented through conduit 21. The pressures of these flowing fluids depress diaphragms 37 and 38 into the recesses which are not blocked by plungers 54, 55 and 56.

When pilot valve 22 is switched to the second position, power gas is introduced into chamber 65 from conduit 24. As the pressure builds up in chamber 65, a force is exerted on piston 46 so that this piston rises against the force of retaining spring 57. Member 53 then engages shorter plungers 50, 51 and 52 to raise these plungers and the diaphragm sections immediately above these plungers. As the pressure continues to increase in chamber 65, suflicient force is built up to overcome washers 49 so that piston is moved downwardly. This retracts longer plungers 54, 55 and 56. The combined plunger movements switch the valve to the position illustrated by the dotted lines in FIG. 1. Carrier gas is then directed through sample loop 20 to displace the volume originally trapped therein into column 10. The incoming sample is vented through conduit 21. Thus, the two positions of the value depend on the introduction of power gas into chamber 65.

In a second embodiment of valve operation, vacuum pump 26 of FIG. 1 is connected to port 25f of FIG. 2. This permits operation with carrier gas and/or sample fluid at substantially lower pressures because the application of vacuum to the under side of diaphragm 38 assists in the downward displacement of the diaphragms in the absence of the passages being blocked by plungers.

For a more detailed description of the construction and operation of the valve illustrated in FIG. 2, reference is made to US. Pat. 3,140,615.

'The use of distribution cap 30 permits the valve to be disconnected from the connecting conduits merely by removing screws 31. When these screws are removed, all of the valve assembly beneath cap 30 can be removed as a single unit. This permits a second valve to be attached to the existing conduits while the original valve is being cleaned or repaired. As previously mentioned, this permits rapid servicing of sampling valves in chromatographic analyzers and facilitates construction because all of the connecting conduits are fastened to a single unit, cap 30.

While this invention has ben described in conjunction with a presently preferred embodiment, it should be evident that it is not limited thereto.

What is claimed is:

1. In a sample valve which includes a first member having first and second faces and a plurality of first passages extending between said faces in spaced relationship with one another, a valve body secured to the first of said first member, a plurality of movable actuating means carried by said valve body and positioned so as to block communication between the ends of selected ones of said first passages at the first face of said first member when actuated, and pressure operated means carried by said valve body to operate said actuating means; the improvement comprising a valve cap having a plurality of first ports and a plurality of second passages therein, the latter extending from respective ones of said first ports to respective locations spaced from one another at a first face of said cap, said cap also having a second port and a third passage extending from said second port to a point at the said first face of said cap; means to secure said cap to said first member so that said first face of said cap engages said second face of. said first member and said second passages communicate with respective ones of said first passages; and conduit means extending from said point through said first member to said pressure operated means.

2. The valve of claim 1 wherein said conduit means comprises a third port in said first member spaced from the first face thereof, a fourth passage in said first member extending from said point to said third port, and conduit means extending from said third port to an inlet of said valve body which communicates with said pressure operated means.

3. The valve of claim 1 wherein said valve body contains a diaphragm which extends across said first face of said first member, and a chamber is formed in said valve body which is in communication with the side of said diaphragm opposite said first face, and wherein said cap has a third port, a fourth passage extending from said third port to a second point at said first face of said cap, and conduit means extending from said second point through said first member to said chamber.

4. The valve of claim 1 wherein said cap and said first member are flat plates with said faces parallel to one another, said first passages extend through said first member in directions generally perpendicular to said faces of said first member, and the ports in said cap are in the side thereof.

5. The valveof claim 1 wherein said means to secure said cap to said first member comprises a plurality of screws which extend through said cap into said first member.

References Cited UNITED STATES PATENTS 3,139,755 7/1964 Reinecke' et al. 73-422 3,140,615 7/ 1964 Broerman 73-422 3,297,053 1/ 1967 McKinney.

3,384,122 5/1968 Harpman 137-62564 LOUIS R. PRINCE, Primary Examiner H. C. POST III, Assistant Examiner UNITED STATES PATENT OFFICE CERTIFICATE OF camEcTIm Patent No. 3,533,295 D. M. Vesper Dated Oct. 13, 1970 It is certified that error appears in the above-identified patent and that said .Letters Patent are hereby corrected as shown below:

Column 4, line 18, "race" has boon omitted between "first" and "of".

SIGNED MU REALEI' 6 Anew 3am M. Fletcher. in mm 1:. sum, :3. .Attesting Officer flomissioner or Pat-ants

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