cfm and water lift

All I can talk about is my personal experience.

I have a Diamonback with dual 3 stage-vacs.  The came in a series with a 1.5" port.  I've used this machine like this for 5 years or so. 

After getting advice from Friendly, I decided to switch them over to parallel.  Not only that, I opened up the 1.5" to a full 2", and put a cool cuff male starter cuff in the hole instead of a 2" barb, which actually isn't even 2".  All I can say is that the vacs are screaming now instead of sufficating in each other.  It doesn't even sound like the same machine.  The vac power seems significantly better than before. 

I can switch it back to series pretty easily, but I don't think I ever will.

I though about adding a 3rd 3 stager.  Steambrite sells a vacuum booster than takes the place of your 6" recovery tank lid.  They also sell a dryer plug adapter that will allow you to plug in up to 4-15amp plugs.  I have decided not to do this at the moment, mainly because I intend on pursuing more commercial accounts, which would render that dryer adapter useless.  It may be a good option to have that booster, just in case one of your 3 stagers gives out at a job.

By the way, if you are not running one of your vacs configured in parallel, I think you need to cover the exhaust hole of the vac not in use, otherwise air will be pulling through that vac.

My first 3 portables were in series.. The last one was in parallel.. No matter which one you run i would still keep your hose runs as short as possible..

Kenny is smoking crack again. In a system that has 200 cfm, 30 cfm is only 15%. The waterlift is barely affected. In a series, the max cfm is 100 with no load. If you have 50 cfm leaking into the system, you've reduced your waterlift by about 50%. Hence the confusion on Kenny's part.

Edited by FriendlyHammer - 18/February/2008 at 7:51pm

Parallel is NOT always the way to go. The best way to measure vac motors is UNDER load, not NO Load conditions. You don't clean that way. you clean with the equivalent of a 3/4" opening. That produces approx a lift of 70"WL and 30 cfm from a single 3 stage vac motor with 25 ft of hose connected operating thru a wand cleaning on the carpet. If you were to run 2 of those vacs in parallel, you would NOT double your vacuums under those operating parameters. Your lift would only rise to 80"WL but your cfm would still be only about 40. Why? Because the resistance at the wand/carpet interface is so strong that without an increase in lift, not much additional air can make it thru there.

If instead the 2 vacuums are in series, the lift will rise to 130"WL, and CFM rises to 50 cfms. That is because the air pressure differential between the air outside the wand(atmospheric)and inside the wand is now greater, causing more air to enter the wand. The resistance at the WCI is the same, but the ability to overcome it has been increased.

So now you know why the Ninja is hooked up in series, not parallel. It works better. Century did extensive testing on both configurations before deciding and PROVING that series works best.

I've read a few other articles on the subjects, still don't completlly get it?

rick007 wrote: i was talking to a dealer who sells and services ninja machines and he said that with a porty higher water lift was more important than cfm. what do you think ? i want to use a 360.