DEVICES FOR THE TRANSFER OF SAMPLE LIQUID

• US 3,681,995 A
• Filed: 06/08/1970
• Issued: 08/08/1972
• Est. Priority Date: 06/09/1969
• Status: Expired due to Term

• Current Assignee: Peter Paatzsch
• Original Assignee: Peter Paatzsch
• Inventors: Paatzsch, Peter
• Primary Examiner(s): Swisher, S. Clement
• Application Number:
  US05/044,267
• Time in Patent Office: 792 Days
• Field of Search: 73/423A,421B 23/253 356/246
• US Class Current: 73/864.15
• CPC Class Codes: G01N 35/1095 for supplying the samples to flow-through analysers for a specific analyser see relevant groups, e.g. under G01N15/00, G01N21/00, G01N27/00, G01N30/00, H01J49/00

Abstract

In an automated testing apparatus of the type in which a series individual liquid samples in separate sample vessels are transferred into individual sample cells, a positive displacement pump is utilized for this transfer, rather than temporary utilization of a large vacuum source. Use of such a pump avoids frothing and the consequent formation of bubbles (which may lead to errors in photometric measurements of the samples in the cells). Additionally a plurality of liquid samples may be transferred by utilizing a single multi-channel positive displacement pump (e.g., of the hose type) even though the samples have substantially different viscosity. A conventional large vacuum source is preferrably still used to empty the sample cells after testing, to insure complete evacuation of the sample material from the cells and the hoses.

Claims

1. In an apparatus for transferring sample liquid from an original sample vessel into a sample cell and for subsequently sucking the sample liquid from said cell by means of a relatively large vacuum source of the type in which a first connecting hose from said sample vessel terminates as a first inlet connection in said sample cell, a second outlet connection from the bottom of said sample cell is connected by a second connecting hose to said vacuum source for ultimately emplying said cell, and a shut-off means is provided in said second outlet connecting hose, the improvement comprising:

a positive displacement pump means is connected to said cell which cell is generally closed, so as to cause a controlled transfer by suction of sample liquid from said original sample vessel to said sample cell, to thereby ensure relatively slow, bubble-free transfer of said sample liquid with said cell.

2. An apparatus as recited in claim 1, in which:

said positive displacement transfer pump means is connected to said sample cell by a third connection, terminating at an upper part of said sample cell.

3. An apparatus as recited in claim 1, in which:

said positive displacement transfer pump is in the form of a hose pump having hose-compressing means movable along a substantial distance while constricting said hose, thereby tending to move a fixed amount of liquid sample.

4. An apparatus as recited in claim 3, in which:

the output side of said positive displacement hose pump is connected to said vacuum source;

so that said hose Pump is connected from said sample cell to said vacuum source in parallel with said second connecting hose, having said shut-off means.

5. An apparatus as recited in claim 4, in which:

said hose pump comprises a cylindrical housing along the interior surface of which is positioned a hose connected to said third sample cell connection, and a motor driven rotor having two mutually offset compression bodies for constricting respective parts of said hose against said cylindrical housing;

a cam disk rigidly mounted for rotation with said rotor;

a shut-off compression body operatively engaging the cam surface of said cam disk and positioned immediately adjacent said second connecting hose in such manner that a portion of said surface of said cam causes said shut-off body to pinch closed said second connecting hose;

whereby a single motor directly controls operation of both said transfer hose pump and opening and shutting-off of said parallel second connecting hose between said sample cell and said vacuum source.

6. An apparatus as recited in claim 3, in which:

the input side of said hose pump is connected to said second outlet connection from the bottom of said sample cell by means of a conduit hose element of sufficient internal volume to accommodate the contents of the entire sample cell, the output side of said hose pump being connected to said vacuum source;

forward stroke means for causing movement of said hose-depressing means of said hose pump through a relatively large suction stroke angle Alpha so as to suck sample liquid from said sample vessel, through said sample cell and into said conduit hose element;

return stroke means for causing movement of said hose-depressing means of said pump in the opposite direction through a somewhat smaller return stroke angle Beta to cause said sample liquid in said conduit hose element to refill said sample cell;

means for subsequently moving said hose-depressing means of said pump to a subsequent intermediate position, in which it releases the depression of the hose of said pump, so as to allow unobstructed communication of said sample cell with said vacuum source, whereby said liquid sample is completely sucked out of the sample cell and said conduit hose element into said relatively large vacuum source.

7. An apparatus as recited in claim 6, in which:

said hose pump comprises an almost complete cylindrical housing extending circumferentially slightly less than 360*;

the pump hose connected to said second cell connection through said conduit hose element being positioned along the internal surface of said almost complete cylindrical housing;

said rotor and its said compression means therefore comprising the said hose-compressing means, the relatively long forward suction stroke and somewhat shorter return stroke of which causes, firstly, said sucking of said sample liquid from said sample vessel through said sample cell and into said conduit hose element, and the somewhat shorter return stroke of which causes said sample liquid in said conduit hose element to refill said sample cell; and

the movement of said rotor-carried compression body to said intermediate position at which said almost complete cylindrical housing is incomplete releasing of said pump hose, so as to cause said unobstructed communication of said sample cell with said vacuum source, thereby sucking said liquid sample completely out of said sample cell, said conduit hose element and said pump hose into said relatively large vacuum source.

8. An apparatus as recited in claim 6, in which:

rinsing means, operating prior to said forward stroke means are provided;

for initially rinsing said sample cell with a portion of the sample in said sample vessel;

said rinsing means comprising means for causing said pump hose-depressing means to move to said intermediate position when said suction pipe is only partially within said original sample vessel, so that said portion of said sample in said Vessel is sucked into the unobstructedly corrected vacuum source through said first connecting hose, said sample cell, said second connecting hose, said conduit hose element, and said pump hose, thereby pre-rinsing all these elements with sample liquid before the actually to-be-tested portion of the sample is placed in said sample cell.

9. An apparatus as recited in claim 2, in which:

means are provided for opening said shut-off means in said second outlet connecting house prior to operation of said positive-displacement pump, while said suction pipe is partially immersed into said original sample vessel;

whereby a portion of said sample liquid is sucked into the unobstructedly connected vacuum source through said first connecting hose, said sample cell and said second connecting hose, thereby pre-rinsing these elements with sample liquid before the remaining portion of the same actually to-be-tested portion of the sample is pumped into said sample cell.

10. An apparatus as recited in claim 1, in which:

said relatively large vacuum source comprises a sealed waste collection bottle connected to a vacuum pump.