Plastic pump vs plastic liner pump

[mmmumuw]

Dear all,
WE have to pump H2SO4 95%, and we need the non metal pump to do so. There are two brand, submit their offer. The teflon lining pump and full non metal pump.
The price is also different.
Do you have any experience which one is better. Or in other word, which application is better than the other.
Thanks,
MW

 

[aspearin1]

I don't have experience with these pumps, but I will speculate that in the event of failure, it seems that repair on the lined metallic pump would be more feasible than an all plastic pump. It may only need a new lining, whereas the all plastic pump may have cracks and voids that cannot be repaired. However, on the flip side, it's possible that the lining may require more frequent repairs than the all plastic pump. Pure speculation, I would predict the plastic lined pump would require more repair in its lifetime, but give consistent efficiency throughout its life. The plastic pump may require less repair, but would have a steady decline in efficiency throughout its life. The metal pump would also have some scrap value at the end of its life (which can be very much prolonged with rebuilds), whereas the plastic pump would likely just become fill.

Have you considered a large peristaltic pump? I've seen these large units clamped to a plastic lined braded SS hose. No wetted parts. Steady flow. Easily replaced. They are flow limiting, though.

ChemE, M.E. EIT
"The only constant in life is change." -Bruce Lee

 

[TZellers]

Not sure of which brands / models you are dealing with, but these days Tefzel/PTFE lined pumps are mag drives, not mechanically sealed pumps. Full non-metallic pumps can go either way, depending on the model / make.

I doubt too many people would repair a Tefzel liner in smaller (ANSI or less) pumps. Just buy a new part.

As far as H2SO4, it isn't that bad to pump. You should get decent life out of either style pump. Both have similar temp ratings I'm sure. If solids are present, I would lean towards the full plastic pump. Nothing like eroding your protective liner (but even CS is compatible with H2SO4 at certain temps and conc). If it's clean and clear, then I would look at seal versus mag-drive, initial price, operating costs and maintenance costs.

 

[mmmumuw]

Dear Tzellers,
We need sealless pump, indeed. Are there magdrive teflon liner pump?
Thx,
Muwardi

 

[TZellers]

Muwardi:

Not sure of your locale, but here is a sampling of Tefzel/PTFE lined pumps:

Goulds (

http://www.gouldspumps.com)

3298, 3299, SP 3298, V3298, Richter Chemie (

http://www.itt.com)model

number?,
Flowserve (

http://www.flowserve.com)

PolyChem 'L' is FRP lined with PFA, PolyChem 'M'
ANSIMAG (

http://www.ansimag.com)

all lined magdrives
INNOMAG (

http://www.innomag.com)

all lined magdrives

Fybroc (

http://www.fybroc.com)has

all FRP pumps, but may be working on or have a lined FRP pump.

Hope that helps.

 

[ccfowler]

Assuming that temperatures and pressures are compatible with a suitable non-metal pump, I would tend to favor that choice for the sake of durability vs. the risk of incidental damage to the lining of a metallic pump. Despite this comment, lined metal pumps can and have provided excellent service lives when suitably selected, operated, and maintained.

In any case, be certain to provide all possible specific application information to the manufacturers of the pumps under consideration. They will have access to unpublished information about the pump design and performance history in similar services. Pay close attention to the manufacturers recommendations and cautions.

One thing that you can count on is that if your selection is based primarily on the initial cost of the pump, the probability of satifactory service and favorable true life-cycle costs will be greatly diminished.

 

[rmw]

If your fluid is not very clean, go with the lined pump. Mag drives have very close clearances in the can section, in order to minimize flux loss across the can. Any particulate matter can get into that area, and scar the parts, or jam the pump.

If it is very clean, and will remain so, this would not be a problem, and mag drives are OK.

Either style of pump has excellent records in sulfuric acid service.

rmw