PTS Flowbench Forum

Happy New year to y'all and now that the holidays are over its time for me to get started on a PTS bench.
My question is, I have two commercial centrifugal Paxton air blowers , one is a model VR-70-hc -375 cfm @ 24" water & 3750 RPM. The other is a model VR-70-86af - 400 cfm @ 20" water and 3300 rpm.(ideal rpm for alot of electric motors and even easier to over or under drive) I thought these would be really neat to use and could overdrive for more capacity if needed. I've done a search on this forum and found it takes roughly 1 hp for every 65 to 70 cfm @28 " so reckoned I was in the ball park. Please correct me if I'm wrong, and I assume these depressions are static with no valve opening.
When I did some research on Paxton"s centrifugal blower webbsite (which only featured their new model air blowers) I calculated I would need about 7.5 hp for each blower to have ample capacity but my math could all be wrong or I missed something. I can come up with the 7.5 hp electric motors although they are somewhat pricey. I would like to keep it all electric with one or two motors as it would make it easy to service durable unit and I don't believe they would generate much heat.
I also was wondering if I can power these blower (s) with say a single 10,12 or 15 hp gas motor in a seperate housing outside the shop so as not to get afixiated. I then can regulate air flow via the throttle and the use anautomated air bleed valve to maintain a constant depression, well something like that anyway.
I want to have the ability to do fairly large BBC heads so would I need one or both blowers in parrellel or am I wasting my time and should just keep collecting my large shop vac motors?
I was hoping someone on this forum had tried using or has experiance with some of the Paxton products. I see Joe Mondellow using some very large centrifugal blowers as well as some other well noted head flow experts.
Looking for opinions or directions.
Thanks in advance!
WB

Vortron make the range of "Air Power" industrial air blowers based on their Vortec superchargers, so it's not a new idea.

A Paxton should work just as well, provided the friction ball drive is still in good condition.
One other potential problem with a Paxton, is that they are made to blow, not suck, and you will need to vent the gear case to the suction side, otherwise it will spew oil out past the shaft seal.

Other than that I expect it should work well, although maximum airflow will be quite limited due to the relatively small intake flow area of the compressor wheel.

I think this would work very good http://www.cincinnatifan.com/centrifugal-hpii.htm

I thought I posted this link once before but I could not find it.

Tony, thanks for the heads up on the suction side seal. I fully understand what you're talking about. I'm not familiar with the interior design so I'll have to take it apart and see what I can do there. Today I spun both of these Paxtons with a 1/2" drill and noticed just like you said , they blow alot off air but was surpised as to the low suction compared to a shop vac. But then again I wasn't spining it 10,000 rpm either. I"m hoping as the rpm increases their efficiency may increase.
I only ask about using these Paxtons as I have two of these already. I have stockpiled four 6.5 hp Sears shop vacs too, just in case the the Paxtons won't work. I can still go either way for this build.

You guys know Bruces bench inside in out , if you guys think I should just ' can ' the Paxtons my feelings won't be hurt. I hope to be a long time student on this forum.

wb

I suppose it depends what condition these Paxtons are in, particularly the epicyclic friction ball speed increaser.

These Paxtons are now getting rather old, and may have seen abuse at some stage, no oil, or the wrong oil will quickly cause problems. Once the friction drive begins to slip under high boost, the end is near..

If the balls or the shaft are burned, grooved, or worn out, I don't think you can get spares to rebuild them anymore.

I would couple it up to your electric motor and do some flow and pressure testing before actually building it into a bench.
If the results are satisfactory, go for it !!

Malvin's idea of using a large industrial pressure blower is what I use in my own bench.
These big low rpm blowers are very quiet and very efficient, much more so than vacuum motors, and if you are patient, they sometimes turn up on e-bay, and if you scrounge around they often sit for years unloved at at machinery graveyards.

A really low ball offer, especially if you act really disinterested (!!) could score you a magnificent flow bench blower for a lot less than you might expect.

Here is one on ebay cost of it is a little high at least I think so .

http://www.ebay.com/itm/NYB-Industrial- ... 3f1fbbe82b

That is definitely the type of thing to get, but it looks absolutely brand new, and with a brand new price tag.

Something like $250 to $350 would be more like it for something that size from a secondhand machinery dealer.
And more like $50 to $200 at a bankruptcy auction or private sale.

Malvin,
That one you show the link is also a 3 phase. Here in Midvale I only have single phase. That was also a 10 HP motor, so it may work great for a flow bench, but not at my house

John

jfholm wrote
Malvin,
That one you show the link is also a 3 phase

Yes I did see that at one time I thought I had one of these to get
for free but when I got there half of it was missing the other half
was so rusted out I was not interested in it. I look around pretty hard
for one in my area here but could not find one I got a rotor phase converter
just for one that was 3 phase but after not being able to find a High
pressure blower like the one in the link above I sold the rotor phase
converter. & Started buying the vacuum motors from Ward at http://www.centralvacuummotor.com/flowbench.htm until I had 20 of them

Tony Wrote
and if you are patient, they sometimes turn up on e-bay

I used what Tony wrote as a example as you could find them on ebay

Believe it or not I was looking at that same exact blower on ebay. Problem being shipping would be a killer. Still a bit pricey for me but I'm still going to keep a look out if these Paxtons don't work

I want to thank you guys for thinking out loud, I do listen and digest everything. You never know where a new idea will be born

WB