High temperature high pressure seal

1. A probe for use with a measurement instrument including a circuit connected to the probe, the probe comprising:

a process adapter for mounting to a process vessel and including a through bore extending from a connector end to a process end;

a tubular body received in the process adapter at the connector end, the body having an outer wall and an inner wall and being solid therebetween, the outer wall having an outer diameter less than an inner diameter of the process adapter at the connector end to define a cavity bounded by the tubular body outer wall and the process adapter, the cavity being open to the process vessel;

a coupling securing the body to the process adapter;

a center conductor coaxial with the tubular body and the process adapter; and

a seal element surrounding the center conductor and encased in the tubular body to provide a seal therebetween;

wherein process pressure in the process vessel increases compressive force between the tubular body and the seal element.

2. The probe of claim 1 wherein the probe has an electrical terminal connected to the center conductor.

3. The probe of claim 1 wherein the tubular body comprises a metal body.

4. The probe of claim 3 wherein the metal body comprises a flange welded to the coupling.

5. The probe of claim 1 wherein the seal element comprises a glass or ceramic seal.

6. The probe of claim 5 wherein the tubular body includes a first counterbore at a process end defining a first shoulder supporting the glass or ceramic seal.

7. The probe of claim 6 wherein the tubular body comprises a second counterbore at a connector end receiving a dielectric insert housed in the coupling.

8. A probe defining a transmission line for use with a measurement instrument including a pulse circuit connected to the probe for generating pulses on the transmission line and receiving reflected pulses on the transmission line, the probe comprising:

a process adapter for mounting to a process vessel and including a through bore extending from a connector end to a process end;

a tubular metal body received in the process adapter at the connector end and having an outer diameter less than an inner diameter of the process adapter at the connector end to define a cavity therebetween, the cavity being open to the process vessel, and having an enlarged counterbore facing the process vessel to define a shoulder;

a coupling securing the tubular metal body to the process adapter;

a center conductor coaxial with the tubular metal body and the process adapter; and

a glass or ceramic seal element surrounding the center conductor and encased in the tubular metal body and engaging the shoulder to provide a seal between the center conductor and the tubular metal body;

wherein process pressure in the process vessel increases compressive force between the tubular body and the seal element.

9. The probe of claim 8 wherein the probe has an electrical terminal connected to the center conductor.

10. The probe of claim 8 wherein the coupling comprises an extension tube housing a dielectric insert.

11. The probe of claim 8 wherein the tubular metal body comprises a flange welded to the coupling.

12. The probe of claim 8 wherein the tubular metal body comprises a counterbore at a connector end receiving a dielectric insert housed in the coupling.

13. The probe of claim 8 wherein the process adapter comprises a first counterbore at the connector end receiving the tubular metal body and a second counterbore at the connector end, and of a larger diameter than the first counterbore, receiving the coupling.

14. The probe of claim 13 wherein the tubular metal body comprises a flange having a diameter greater than the diameter of the first counterbore and received in the second counterbore to be welded to the process adapter and the coupling.

15. The probe of claim 8 wherein the center conductor comprises a pin conductor extending through the seal element and connected to a probe rod extending into the process vessel.

16. A probe for use with a measurement instrument including a circuit connected to the probe, the probe comprising:

a process adapter for mounting to a process vessel and including a through bore extending from a connector end to a process end;

a tubular metal body received in the process adapter at the connector end, the tubular metal body having an outer wall and an inner wall and being solid therebetween, the outer wall having an outer diameter less than an inner diameter of the process adapter at the connector end to define a cavity bounded by the tubular metal body outer wall and the process adapter, the cavity being open to the process vessel;

a coupling securing the body to the process adapter;

a center conductor coaxial with the tubular body and the process adapter; and

a seal element surrounding the center conductor and encased in the tubular body providing a hermetical seal therebetween;

wherein process pressure in the process vessel increases compressive force between the tubular body and the seal element.

17. The probe of claim 16 wherein the metal body comprises a flange welded to the coupling.

18. The probe of claim 16 wherein the metal body includes a first counterbore at a process end defining a first shoulder supporting the seal element.

19. The probe of claim 18 wherein the metal body comprises a second counterbore at a connector end receiving a dielectric insert housed in the coupling.