Pumping Bleach&NaOH

[ciise]

Hi all...

I am working on a project to size a pump for for the following application parameters:

Flow=120GPM
Head=120
Temp=120F
Press=atmospheric

here is the interesting thing: The fluid to be pumped is 10%vol. Caustic soda and 15%vol. Bleach. Is Specific Gravity of 1.2 conservatively good?
Now that I have to select the pump material, is 316SS good for this application?

I am new with the company and my supervisor has business background, so, he left me to decide what is good for this application.

Any comments on my unexperienced conclusions?

Thanks in advance:

 

[SteveWag]

No metal is serviceable long in 15% bleach. I know Hastaloy and titanium are recommended, but be prepared for about 1 year, max service life. A magnetically coupled plastic pump is about the only thing that will give good service.

Look at this

http://www.finishthompson.com/cp-se...=60&speed=3450&flow=120&head=120&sg=1.2&pos=4

What ever you find that works with bleach will probably work with caustic.

Steve

 

[micalbrch]

Steve is right. Try a plastic pump. PP or PVC are good for caustic soda. "Bleach" is a little bit general to select a material but any plastic pump vendor can help you. You will save a lot of money with a plastic pump over a stainless steel pump.

 

[moltenmetal]

Either plastic, or plastic-lined ductile iron, mag-driven, is the best option for this service.

In our experience the vulnerable part will be the mechanical seal rather than the body material in a metallic pump.

 

[TenPenny]

We've had good experience with tefzel lined mag drive pumps on these services. Depending on what you're doing with the caustic, you may want to flush the pump out before shutting it down - if the caustic salts out, it'll be hard on the pump internals. Same thing holds true with a mechanically sealed pump - tne caustic salts out and tears up the seals.

 

[ciise]

Thanks for the this valuable advice. Really appreciate it.

 

[EdStainless]

The flushing comment is right on. You will tear up ceramic bearings if you let solids crystallize during outages. I have seen systems with automated freshwater flush every time the pump was shut off.

Use non-metallics. I wouldn't used coated parts but solid polymers. With caustic you can't use glass reinforcement. Use other forms of loading to get the strength that you need.

For other parts use Ti and ceramic.

You may be using FRP piping. Be aware that if there is damage or failure of the inner resin layer you will start attacking the glass fibers and rapid deterioration may follow.

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