Adjustable, retractable probe insertion assembly
View Patent ↗An adjustable insertion assembly for an electrochemical sensor includes an electrode holder to receive the sensor, having a distal aperture to permit process fluid to contact the sensor. A receptacle slidably receives the holder, for a sliding range of motion extending from fully inserted to fully retracted positions. An open distal end portion of the receptacle extends through a wall of a process fluid vessel, so that the aperture is open to the process fluid when fully inserted, and closed when fully retracted. A leverage member is releasably movable relative to the receptacle, and moves with a captured extension. An abutment of the receptacle engages the extension so that movement of the leverage member in opposite directions alternately clamps and releases the electrode holder relative to the receptacle to substantially prevent and permit movement at substantially any point within the range of movement.
1. A method of adjustably inserting an electrochemical potential measurement sensor into a process fluid, the method comprising:
(a) providing an insertion assembly, the insertion assembly comprising:
an elongated electrode holder, configured to receive therein an electrochemical sensor having measurement and reference half cells, the electrochemical sensor configured for electrochemically responding to a process analyte upon contact with a process fluid;
a receptacle configured to slidably receive the electrode holder therein, wherein the electrode holder is configured for slidable movement within a range of motion extending from inserted to retracted positions;
the receptacle having an open distal end portion configured for extension through a wall of a process fluid vessel, wherein the electrode holder is open to the process fluid when the electrode holder is disposed in inserted positions, and closed to the process fluid when in the refracted position;
a leverage member coupled to the receptacle, and configured for releasable movement relative to the receptacle;
an extension captured by the leverage member and configured for being moved by the leverage member relative to the receptacle;
the receptacle having an abutment configured to engage the extension in a sliding, interference fit, so that movement of the leverage member in opposite directions alternately clamps and releases the electrode holder relative to the receptacle to substantially prevent and permit movement at substantially any point within the range of movement; and
a flange disposed at the distal end of the electrode holder, the flange sized and shaped to engage the distal end of the receptacle and prevent further proximal movement of the electrode holder relative to the receptacle when the electrode holder is disposed in its retracted position to provide a mechanical stop for the electrode holder and close the aperture of the receptacle to the process fluid;
(b) extending the open distal end portion of the receptacle through a wall of a process fluid vessel;
(c) placing the electrochemical sensor into the elongated electrode holder;
(d) slidably placing the electrode holder into the receptacle, wherein the electrode holder is configured for slidable movement within a range of motion extending from an inserted position in which the aperture of the electrode holder is open to process fluid within the vessel, to a retracted position in which the aperture of the electrode holder is closed to the process fluid;
(e) sliding the electrode holder into a fluid insertion position at any of a plurality of locations within its range of motion;
(f) clamping, with the leverage member, the electrode holder in the fluid insertion position;
(g) operating the electrochemical sensor to detect an analyte associated with the process fluid;
(h) releasing, with the leverage member, the electrode holder;
(i) sliding the electrode holder into the retracted position to engage the distal end of the receptacle with the flange, prevent further proximal movement of the electrode holder relative to the receptacle and close the aperture to the process fluid;
(j) clamping, with the leverage member, the electrode holder in the retracted position;
(k) removing and replacing the electrochemical sensor after said (j); and
(l) repeating said (e)-(g).
2. The method of claim 1 , further comprising repeating said (e)-(g) at another of the plurality of locations within the range of motion.
3. The method of claim 1 , wherein the leverage member comprises a tube nut disposed about, and threadably engaged with a proximal end of the receptacle, the tube nut being configured for threaded, axial movement relative to the receptacle.
4. The method of claim 1 , wherein the electrochemical sensor is configured for being coupled to a process variable transmitter.
5. The method of claim 1 , wherein the measuring half-cell comprises a pH electrode.
6. The method of claim 1 , wherein the measuring half-cell comprises a selective ion electrode.
7. The method of claim 1 , wherein the measuring half-cell comprises a fluoride ion selective electrode.
8. The method of claim 1 , wherein the measuring half-cell comprises an oxidation-reduction potential electrode.
9. The method of claim 1 , wherein the distal end of the receptacle includes a pipe thread, wherein said (b) comprises threading the pipe thread of the receptacle onto the wall of a process fluid vessel.