Ron,

This program is written in BASIC. It contains routines for selecting the Halide type: Br, I, and Cl and allows the user to enter a make with up to 15 segments in the flow-profile with holds.

It has ability to pre-heat the z-batch and utilizes both shallow and deep temperature sensors. It also has routines for storage and retrieval of the various “makes” should you want to repeat a particular flow profile. There are also subroutines for VAg calibration whereby the silver billet, triple junction reference and temperature probes are immersed in standard solutions and checked for proper operation.

There are detailed error routines for detecting any drift along with suggested possible causes such as noisy signals caused by faulty connections, plugged junctions, leakage rate of the salt bridge solution and poorly platted silver electrodes. It offers corrective actions to replate the silver billet electrode, and replace the lower bridge junction. This combined with the RIT papers and your many posts on VAg have given me a clear understanding of the topic. All-in-all, it lays out the details necessary to construct a working system migrated to todays programming languages and single-board microcontrollers.

On a related thread you mention the need for higher purity silver for the electrodes and importance of the uniformity of plating. I purchased two lengths of high purity silver rod, diam. 7.0 mm, 99.99%, Sigma-Aldrich item number 26,562-4 (10 grams = 25 mm or 40 grams = 100 mm) for fabricating the silver Billet electrodes. I am planning to round-off and polish the end of the rod to achieve a "bullet" geometry and mount it in the end of a Teflon rod prior to plating. I hoping this smooth-surface geometry will improve the uniformity of plating over wire-type electrodes.

George