Home /
T.O.C.
FAQs
 
Good
Books
Ref.
Libr.
Advertise
Here
Help
Wanted
Current
Q&A's
Search 🔍
the Site
pub Where the world gathers for
plating, anodizing, & finishing Q&As since 1989





-----

Unexplained fluctuations in ORP values for chromium reduction





May 27, 2010

We have a hex-chrome bearing waste stream from chem film on aluminum, EP, and chromate on zinc processes. We reduce the chromium by dropping the pH to <2.10 and adding sodium metabisulfite in a rection tank. We have noticed that when the stir motor is on, the ORP values are up to 30 mv higher than when the tank is not in use. When the stir motor is running and the tank is in standby (no solution flow) there is variation of about 5-8 mv, but the average value is constant. If we then turn the tank (and stir motor)off, the variation diminishes as the average value drops, and then stabilizes at a fixed value.

The tank is fiberglass construction; we have tried using a ground lead to the solution to no avail. Any ideas on the cause, and if prudent, a solution?

Thanks in advance.

Willie Alexander
MF Supervisor - Colorado Springs, Colorado


none
finishing.com is made possible by ...
this text gets replaced with bannerText
spacer gets replaced with bannerImages

Q, A, or Comment on THIS thread -or- Start a NEW Thread

Disclaimer: It's not possible to fully diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations might be harmful.

If you are seeking a product or service related to metal finishing, please check these Directories:

 
Jobshops
Capital
Equipment
Chemicals &
Consumables
Consult'g, Train'g
& Software


About/Contact    -    Privacy Policy    -    ©1995-2023 finishing.com, Pine Beach, New Jersey, USA