Abstract: Apparatus for calibrating a conductivity instrument having a conductivity cell and a conductivity measuring instrument operatively associated with the conductivity cell, includes a conduit for supplying high purity water to be measured; a first flow line for supplying the high purity water from the conduit to the conductivity cell; a second flow line for supplying the high purity water from the conduit to the conductivity cell; a mixed bed ion exchanger in the second flow line for de-ionizing the high purity water flowing through the second flow line; and a valve which selectively supplies the high purity water to the conductivity cell, from either the first flow line to provide a conductivity measurement of the high purity water or the second flow line to calibrate the conductivity cell.

Abstract: Improved apparatus for bringing a fluid in a process stream in contact with a sensor is disclosed. The present invention uses the kinetic energy of the process fluid to convey some of the fluid to and from the sensor, as opposed to the prior art practice of inserting the sensor itself into the process fluid stream. A nozzle is placed into the process fluid stream facing into the direction of flow. A small portion of the flowing process fluid is trapped by the nozzle and some of its kinetic energy is converted to pressure. This pressure causes a flow from the nozzle into a conduit through an open valve to the sensor. The fluid continues past the sensor and returns to the process fluid stream through the same valve. In one embodiment, the path for incoming fluid and exiting fluid are separate paths. In a second embodiment, the incoming fluid and exiting fluid exist coaxially.