DE Filter Head Loss Outperforms Cartridge?

[aerospa]

I was looking around at filters to replace my nearly 30 year-old Pentair SMBW 2060 DE filter (60 sqft) as part of a general equipment pad revamp, and I was initially leaning towards a new cartridge filter as it seems to be in vogue.

I learned a few things:
1. From a forum search, DE vs. Cartridge vs. Sand takes a backseat to pool chemistry in terms of water clarity.
2. People who have DE filters seem to like them.
3. My 30 year old DE filter features roughly half the head loss of a brand new cartridge filter.

That last point is one I want to talk about. I pulled the head loss vs. flow rate curves from my DE filter's manual and from the manual for a Pentair Clean and Clear Plus (CCP), and plotted them on the same graph:




Now that's interesting. You'd think with a DE filter capable of filtering particles 3-5x smaller than a cartridge filter, you'd have to pay a head-loss penalty. But not according to the manual.

Two questions:
1. Does this result surprise you?
2. Would you suggest I re-use my perfectly functioning 30 year-old DE filter during the equipment pad swap-out/replumbing?

I mean, what's the point of "upgrading" if nothing is improved...

Cheers!

 

[JamesW]

I'm not sure that the head loss curve for the DE is accurate.

I think that they might have put feet instead of psi for the head loss.

For example, at 140 gpm, the head loss is shown as 15 feet, but 15 psi (35 feet) is probably a more realistic number.

Put 140 gpm on your filter and there's no way that it will only register 6.5 psi (15 feet).

What is your filter pressure at different flow rates?

 

[Poolbreh]

Comparison between cc520 and comparable fns 60

 

[JamesW]

The head loss for the FNS at 140 gpm is 12 psi and that is probably without the multiport.

Add the multiport head loss and it is probably 15 psi.

 

[JamesW]

Head-Loss Specs for Pentair Multiport Valves

If anyone needs head loss specs for Pentair, Hayward, Praher or Sta-Rite multiport valves, the following info may help. I had no luck on Pentair website finding head loss curves for the Pentair 261055 multiport valve I am installing on a Pentair Quad DE filter. So, I found this information from...

www.troublefreepool.com

https://images.inyopools.com/cloud/documents/PRAHER-MPV-OWNERS-MANUAL-MPV031017-REV-2.pdf

 

[aerospa]

I subscribe to JamesW's theory that the head loss units were mislabeled in the plot. I replotted the data as both feet of head and psi, and I added the FNS filter data on there. I'm still surprised; if the SMBW 2000 data is in fact psi, that puts it on-par with the Clean and Clear Plus cartridge filter performance. I have reason to believe that the SMBW data includes the multiport valve on the bottom because there are separate curves for the 'SM' series on the same plot, and these curves show much less head loss for the SM. The SM series doesn't have a backwash valve... 'BW' = BackWash.

Also, why do I have different data for the CCP than Poolbreh?

https://www.pentair.com/content/dam/extranet/nam/pentair-pool/residential/filters/clean-and-clear/clean-and-clear-plus/clean-and-clear-plus-guides-manuals/clean-and-clear-plus-install-guide-english.pdf

https://images.inyopools.com/cloud/documents/pentair-filters-sm-smbw-2000.pdf

My consolidated plot:

 

[JamesW]

Also, why do I have different data for the CCP than Poolbreh?

Different manuals have slightly different graphs.

Check the manual revision dates.

Maybe they redid the tests?

 

[JamesW]

The FNS curve shows 12 psi at 140 gpm, so your plot is not accurate for the FNS.

 

[aerospa]

Yes I had the axes mislabeled.

 

[JamesW]

Still not correct.

100 GPM for the CCP is about 6.5 psi, but you have 15 psi.

 

[JamesW]

Yes I had the axes mislabeled.

I once had my axes mislabeled as hatchets.

 

[1poolman1]

I once had my axes mislabeled as hatchets.