What concentration of acetic acid?

[Nitzey]

We need to pump acetic acid into our process, but when I got the cost estimate for a mass flow meter, it was extremely high. It was so high because of the Hastelloy C needed for glacial acetic acid. So, what concentation can I feed without using an exotic stainless steel? 25% is not considered corrosive, but this dilute is inconvenient.

 

[chemebabak]

Nitzey,

Do you need to use a mass flow meter? There are other types of flow meters that are not as expensive, such as orifice plates and electromagnetic flow meters. Are you using Hastelloy C for the pump and piping? If you are using 316SS then you could most likely use that for the meter. However, you should consult with a metallurgist. Consider posting a link to this thread in the Metallurgy area. (

http://eng-tips.com/threadcategory.cfm?lev2=15

)

 

[chemebabak]

By the way, Cole Palmer (

http://www.coleparmer.com/Chemical-Resistance

) gives an "Excellent" rating for Glacial AA and 316SS:

The following is copied from

http://www.coleparmer.com/Chemical-Resistance

Chemical Compatibility Results
Materials with a Compatibility rating of
A-Excellent for your selected Chemical are listed below:
New search
Chemical Selected:
Acetic Acid, Glacial
Shop now
Material

Compatibility
Carbon graphite A-Excellent
Carpenter 20 A-Excellent
Ceramic Al203 A-Excellent
Ceramic magnet A-Excellent
Hastelloy-C® A-Excellent
Hytrel® A1-Excellent
Kel-F® A2-Excellent
NORYL® A-Excellent
Polypropylene A1-Excellent
PPS (Ryton®) A-Excellent
PTFE A-Excellent
PVDF (Kynar®) A1-Excellent
stainless steel - 316 A-Excellent
Titanium A-Excellent
Explanation of Footnotes
1. Satisfactory to 72°F (22°C)
2. Satisfactory to 120°F (48°C)

Ratings -- Chemical Effect

A = Excellent.
B = Good -- Minor Effect,
slight corrosion or
discoloration.
C = Fair -- Moderate Effect,
not recommended for
continuous use. Softening,
loss of strength,
swelling may occur.
D = Severe Effect, not recommended for ANY use.
N/A = Information not
available.

 

[Nitzey]

Thanks for the replies. A mass meter is preferred here since the flow is very low and we are feeding it into an emulsion. pH shock is to be avoided for emulsions and I want to keep the flow as steady and as accurate as possible. I have checked with well known suppliers of glacial acetic acid and they recommend 316L and even 304 stainless steel as compatible materials. However, I am not going to argue with the mass flow meter people(MicroMotion) as I trust them too.

I will try to post a link in the metallurgy section.

 

[moltenmetal]

Temperature is what matters. Look up the NACE reference. For cold glacial (but not SO cold that it actually freezes- be careful of that, hence the name), 316SS is OK. Warm it up a bit and you'll be in trouble quickly.