NaOH Getting Cold

[ozfish]

I am using 50% strength caustic soda with a dosing unit. The caustic is outdoors and is in a region where outside air temps will drop below 10 degrees C.

What is common practice to keep the liquid warm.

I have read somewhere in the past that in colder climates that the concentration should be reduced to 25% - why is this and why does it change the temperature range?

Thanks

 

[cub3bead]

Tank heaters may be used to keep the 50% caustic above the freezing point (11.1-12.2 C).

By diluting the caustic to 25% lowers the freezing point to -12 C. Diluting to 19% lowers it to -28 C.

A good reference for caustic soda can be found at

http://www.oxychem.com/products/handbooks/caustic.pdf

 

[ozfish]

Thanks for the reply. I purchase the Caustic in 1000 Litre plastic containers.

Can you point me in the direction of tank heaters? Are they simple submersible units or are you talking a specially designed tank with heating coils?

Thanks

 

[cub3bead]

Somehow I knew that you would say that you were using plastic tanks. So you can't use a heater that gets too hot otherwise the tank will melt and then you have a real big mess to deal with.

A couple of thoughts though, you might try a bung insertion heater like Ogden manufactures or a flexible strap on type such as Watlow makes. Two web referrences follow. I would suggest that you contact them directly and confirm suitablility for the intended service.

http://www.thomasregister.com/olc/47901558/proces7x.htm

http://www.watlow.com/products/heaters/ht_flex.cfm

Good luck and let me know how things work out.

 

[lattar]

You wrote that it is a dosing unit. There is propably not a constant flow in pipes. So you have to also remember out-door pipe-lines. Electric heated lines can be used in this kind of situations.

I have seen somekind of electric-heated clothes which can be used for heating in cold climete. Clothes are for small barrels (at least up to 200 litres) and for valves. Anyway this is propably not the best alternative for you but i think you should also think ouside heating as one option.

 

[ehiatt]

Diluting it to 25% would work, but the best bet for the same strenght would be to add 5-10% caustic potash.

 

[saxon]

ozfish, Have you thought of building a heated shed to put the containers in?

saxon