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What concentration of acetic acid?

What concentration of acetic acid?

What concentration of acetic acid?

(OP)
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.   

RE: What concentration of acetic acid?

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 )

RE: What concentration of acetic acid?

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

Quote:


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.

RE: What concentration of acetic acid?

(OP)
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.   

RE: What concentration of acetic acid?

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.

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