If the agitator was purchased from a vendor, ask them for advice for your particular application.
If you are re-using some equipment for a different application and the original agitator was purchased from a vendor, ask them for advice for your new application.
Times are hard and they'll be glad to help you out.
If it's a "home made" agitator or you are re-using some equipment for a different application and the original agitator was "home made", I recommend you get a good book on the subject. Oldshue has a good book on agitation. He's aligned with Lightning Mixers. Chemineer has two reprints available through Chemical Engineering magazine. One is on fundamentals and the other is on advanced agitation. If you have a good relationship with your local Chemineer vendor, he'll give them to you.
If you want "our" help, then we need a lot more detail, like:
Describe application (blending, solids suspension, reaction, emulsification, liquid-liquid dispesion, etc.)
Physical properties (water-like, s.g., viscosity, Newtonian or non-Newtonian, etc.)
Level of agitation needed (mild, violent, medium)
The more details the better.
