Rubber Seals being slowly dissolved in Peracetic acid?!?

[Brewberosa]

Has anyone any experience of seals being destroyed by Peracetic Acid? I have noticed the seals in a few butterfly valves wearing away. I know Nitric Acid is known to do this but not peractic. I assumed the material was EPDM but surely peracetic acid does NOT have that effect. The seals have been sitting in a Peractic Acid bath. Maybe they are not EPDM?

[dick murton]

Yep

EPDM is gradually oxidised and therefore chewed up by PAA, especially if it is over strength. Change to Viton seals.

[TGTimm]

Silicone seats also hold up well in PAA.

What concentration of PAA are you using? Anything more than a couple hundred ppm will eat most organic-based seals up.

[jebzter]

PAA is a very strong oxidizer, I would not use it as a parts soaking solution. Just keep everything clean and dry, then dip before use. PAA kills very rapidly, so a long soak is not required.

[Todd Hicks]

I still like 5-Star StarSan dilution in one of those double lidded plastic storage totes for my COP parts bin. The solution lasts a few days, cleans, surfacts, non rinse, and still kills even when it gets a bit dirty.

Somebody tell me I am wrong. I am open to new things now that I am opening a new brewery.

Damn I am stubborn. Help.

COP = Clean Out of Place

[Brewberosa]

The PAA bath is not measured but suffice to say the concentration is low. I would guess 200ppm tops. That is why I am so surprised. I have seen breweries using much stronger concentrations without any negative side effects.

[Brewberosa]

Thanks for the info. How do viton and silicone hold up against nitric?

[TGTimm]

What the heck are you using nitric for? We use a nitric/phos mix for acid washing, and our seals--mostly Buna and Silicone--hold up just fine. Straight nitric acid is only used for passivating new equipment.

I've experimented with various seat materials for butterfly valves. We also use a PAA bath for our parts, and the EPDM was the fastest to become hard, brittle, and just fail.

Given my druthers, I'd eliminate the PAA bath. Unfortunately, the brewers are stuck on it.

[Brewberosa]

[QUOTE=TGTimm;195780]What the heck are you using nitric for?

East English Water is hard as nails. I wish I was in Oregeon.

[DieselDynamo]

Has anyone any experience of seals being destroyed by Peracetic Acid? I have noticed the seals in a few butterfly valves wearing away. I know Nitric Acid is known to do this but not peractic. I assumed the material was EPDM but surely peracetic acid does NOT have that effect. The seals have been sitting in a Peractic Acid bath. Maybe they are not EPDM?

This totally happens. EPDM has a higher resistance but anything over 100 ppm PAA will erode it too.

Sent from my SPH-L720T using Tapatalk

[dick murton]

I hope you are not using nitric acid to soften brewing liquor. Use sulphuric acid, phosphoric or lactic acids depending on what you are brewing. Murphys also sell their water treatment acid (AMS) which is a mix of sulphuric and a little hydrochloric acid, though I would prefer to add simple sulphuric acid and add a little more calcium chloride, though you may be able to add their mixed acids and not add any gypsum or calcium chloride at all to get the ionic balance you are looking for.

[Brewberosa]

I hope you are not using nitric acid to soften brewing liquor. Use sulphuric acid, phosphoric or lactic acids depending on what you are brewing.

Don't worry, I am not.