Corrosion Resistance

[cadman99]

Plese be gentle as I am NOT a CE! I have an application where I use metal probes (currently 316) to monitor fluid levels in a tank (ink) through continuity checks. I am afraid I am not sure of the electrical specs as my EE is out on vacation. I have a NEW ink which contains an Ammonium Bromide Salt @ 2%. This is corroding the probe horribly (which I'm sure all of you saw coming). Is there a material which will hold up to these extremes. I already plan on cutting my time between checks by 90%. I have heard Hastelloy CR would work. Any other ideas? Thank you ahead of time for any assistance you can provide.

 

[unclesyd]

Hastelloy C would be good one try. The only problem with Hastelloy C is that is does like an oxidizing environment at all.

We use Hastelloy C on sevral streams where bromides and iodides salts are the main ingredients.

 

[ProcessWaterChemist]

You can find both float sensors and ultrasonic level sensors at automationdepot.com. There are several others as well. Do not buy any metallic sensor that will contact the salt solution. Salts Etch Metals! 2% = 20,000 PPM

 

[moltenmetal]

You can get capacitance and guided wave radar level probes which have no metallic components on them at all. You can also get ultrasonic level devices which don't contact the product at all. Unless your ink is under pressure and hot, Hastelloy is wasted on this service.

 

[EdStainless]

It really depends on what else is in the ink. 2% isn't as strong as seawater, and there are a lot of alloys for that.
The most common are the 6% Mo superaustenitic grades like AL-6XN.

= = = = = = = = = = = = = = = = = = = =
Still trying to help you stop corrosion.
formerly Trent Tube, now Plymouth Tube
eblessman@plymouth.com
or edstainless@earthlink.net

 

[kenvlach]

For the existing design (continuity), some stiff tantalum wire is perhaps best.

 

[777gne]

Radar can be problematic if not kept clean, if the product tends to foam, or if the tank geometry is unusual.

If you can get AL6XN probes I'd go that way, or possibly ultrasonic.

 

[unclesyd]

I checked yesterday to see what we used for level probes in similar materials. All probes where Bromine or Iodine salts are present we use Hastelloy C. The secret to our success with Hastelloy C is that the instrument shop purloins Hastelloy C welding rod from the fab shop for the probes.