METAL IMPELLER PUMP VERSUS POLYMER IMPELLER PUMP 3

[minengr76]

Hi,
I am sizing pumps for slurry project. Some part of the process contains water while some part contain slurry. My supervisor mentioned that i size for pumps with metal impellers but gave no explaination. I will like to know the advantage of a metal impeller pump over a polymer impeller pump. In which applications will one be preffered over the other.

Thanks,
minengr76

 

[itdepends]

Depends on what your pumping- for example

Corrosive fluids may require non-metal impellors- or rubber lined impellors- but once the rubber goes- your back to the same problem.

Rubber lined impellors can give better wear resistance- but are more prone to cut damage (e.g. if pumping sharp, freshly crushed material)- in which case metal impellors may be better.

Personally I'd prefer metal impellors that are corrosion resistant to what I'm pumping- mainly because the potential for decreased wear with rubber lined impellors isn't worth the grief of pulling bits of rubber out of downstream processing equipment.

Cheers

 

[Artisi]

why don't you ask your supervisor?

Reasons maybe that the pumps being used aren't manufactured with a polymer option or interchangeablity with other pumps or your supervisors preference based on prior experience.

itdepends (Chemical) - your statement is far too broad regarding rubber lined pumps, in some installations in mineral dressing applications rubber will outlast hard metal many times over and today a number of manufacturers have thick-rubber lined pumps for use on ball mill discharge which is probably the toughest pump duty ever.

 

[TenPenny]

Since you are referring to a slurry application, I will assume that you are meaning rubber lined impellers vs metal impellers. Rubber lined impellers are superior for some abrasive slurry applications, whereas the metal impellers have higher allowable tip speeds, which means higher head capabilities. That may possibly be why he was suggesting metal impellers.

 

[minengr76]

Thanks for your contribution guys. Maybe i wasn't really clear on my question. This is what i am trying to understand, the impeller of pumps can be made of either Metal material or a Polymer material,OK. This impellers can also have rubber linning or metal linning. Specifically i am refering to Warman Centrifugal Slurry pumps.Both pumps mentioned below are 8/6 pumps, the only difference is the material the impeller is made from.

A brief spec of the pumps impeller is stated below
IMPELLER IMPELLER
Vanes-5 Vanes-5
Vane Dia-510mm Vane Dia-510mm
Type-closed Type-closed
Material-Metal Material-Polymer

LINER (Norm Max r/min) LINER (Norm Max r/min)
Metal 1000 Metal 940
Polymer 1000 Polymer 1500

My manager said the reason for choosing an impeller with metal material is because the mineral to be pumped are abrasive in nature and will wear off an impeller made from polymer faster. This i argue because after a little bit of research, i found that both type of impellers can actually withstand abrasion.

I need more insight on this, so that i can understand the advantages of
(a) Metal impeller versus polymer impellers
(b) Metal linings versus polymer linings.

Thanks.

 

[Artisi]

Are you calling rubber - polymer?

 

[minengr76]

Yes, Rubber is a form of polymer (elastic hyrocarbon polymer) and Plastic is also a polymer. I guess that is what the specification was refering to.

 

[itdepends]

Artisi- I did say rubber lined pumps can offer better wear resistance- but are more prone to cutting from sharp material. I wouldn't consider ball mill discharge to be "sharp". I'd consider a freshly crushed (e.g. quarry slurry) to be sharp.

I'd agree with using rubber lined pumps on ball mills- as long as you don't have heat exchangers downstrem (like I do) which don't appreciate the lumps of rubber that can come off.

Cheers

 

[itdepends]

oops forgot to ask

minengr76
1)What are you pumping (what is the liquid, solid (type, particle size, where's it coming from, is it corrosive)
2)What/where are you pumping it to.
3)What is the discharge head and how fast are you going to have the pump going? (rpm and tip speed)

 

[Artisi]

minengr76 - needed to check if you were talking about rubber or "plastic". Comments to itdepends question re pumped material will help with the right answer.

But to answer your intial post, the normal rule of thumb is, large hard solids- metal, fine abrasive solids - rubber, although with thick-rubber liners that a couple of pump manufacturers can now offer or the use of the very hard abrasive resistant hi-chrome irons available today in some cases be reversed.

Why not ask Warman - who else is better qualified to make a selection on materials for you.

 

[jet1749]

Hi, i've used Warman 3/2 CAH rubber lined pumps with rubber lined impellers successfully on Water with Sodium Thiocyanate and Volcanic Ash duty. One thing to bear in mind when using rubber lined impellers is that they can't be trimmed. So will require either a belt drive or vfd to achieve duty point, something that a metal impeller will not need.

regards

John

 

[devaxrayz]

Mineng76

I need more insight on this, so that i can understand the advantages of
(a) Metal impeller versus polymer impellers
(b) Metal linings versus polymer linings.

Dont forget about operating temperature. Metal impeller withstand with more higher temperature

And also what type of fluid pumped. Although polymer/rubber is more applicable in corrosive environment, it might not suitable for some material, depends on what type of polymer you use for the impeller (material compatibility)



-rayz-