two roots blowers in series

[idreadnought]

Porty guys run two vac motors in series to increase the vacuum pressure. Could you run two roots blowers in series to do the same thing? Basically one above the other and running a belt over them both. Anyone know if this will work?

 

[Duane Oxley]

You'll get an increase in lift as a result... not necessarily in CFM.

 

[idreadnought]

how much do you think? up to 22 or 23hgs? Any downsides besides the hassle of building a machine that way?

 

[Duane Oxley]

If I remember correctly, either Steam Genie or White magic did it back in the 1980's. Maybe both of them did.

Shawn Forsythe could tell you from experience. I'm telling you from a logic perspective.

We did do portables that way in the 1980's. Two, two- stage vacuum motors, in series. If I remember correctly, either alone generated 90 inches of water lift. Together, they generated 120. With that in mind, if positive displacement truck mount blowers net a similar increase to tangential electric vacuum motors, you'd expect to see a 1/3" increase in lift.

There is the concern of feeding pre- heated airflow to the second blower, however. In portables, it was always the second motor (the one that was fed the pre- heated airflow from the exhaust of the other) that needed replacement first.

 

[Dolly Llama]

my first TM had twin 33's driven by a 20hp Onan .
They were in series though...one went right into the next one
a Steam Genie Hyrdogenie

Shawn Forsythe could tell you more about the virtues than I can.
I didn't know squat about TMs then.

I only know it's sucked OK, made good heat and died a violent death in a roll over crash two years into the biz



..L.T.A.

 

[bob vawter]

my first TM had twin 33's driven by a 20hp Onan .
They were in series though...one went right into the next one
a Steam Genie Hyrdogenie

Shawn Forsythe could tell you more about the virtues than I can.
I didn't know squat about TMs then.

I only know it's sucked OK, made good heat and died a violent death in a roll over crash two years into the biz



..L.T.A.

Yes a Steam Genie wit two 33's...had a fellow bring one to me to work on...the belt system was a clusterfook......

 

[lance]

Lots of lift is needed only on very long hose runs. Now that 2.5 inch hose is available, losing lift is lessened a lot more than when using 2 inch hose.

A primo single wand set-up would be 28 hp engine, a 45 blower, a General pump (if Bob V. is in charge that gets changed to a Wanner), belt driven, using a Bayco valve set at 17 inches of lift. Add to that 2.5 inch vac hose and a 2 inch wand.

For dual wanding look at the Powerclean Genesis D-XT. It's basically a doubled up design of the single wand set-up. Lots of horsepower, lots of vac, and using 2.5 inch hose for both wands.

 

[dirt smackdown]

I think if they were either set apart by a cooling box like a waste tank type of thing the heat wouldnt be as severe to the second blower. but with the tangiel vacs the air volume is so low that was the only option to get lift. but with blowers I would try paralel side by side. direct drive on one and belt to the other from there.

 

[bob vawter]

Lots of lift is needed only on very long hose runs. Now that 2.5 inch hose is available, losing lift is lessened a lot more than when using 2 inch hose.

A primo single wand set-up would be 28 hp engine, a 45 blower, a General pump (if Bob V. is in charge that gets changed to a Wanner), belt driven, using a Bayco valve set at 17 inches of lift. Add to that 2.5 inch vac hose and a 2 inch wand.

For dual wanding look at the Powerclean Genesis D-XT. It's basically a doubled up design of the single wand set-up. Lots of horsepower, lots of vac, and using 2.5 inch hose for both wands.

YES...i forgot!
we DID put a wanner on it....it was STILL a POS!

 

[Desk Jockey]

my first TM had twin 33's driven by a 20hp Onan .
They were in series though...one went right into the next one
a Steam Genie Hyrdogenie

We also had a hydro Genie and yes it did run two Sutorbilts in series.

 

[Shawn Forsythe]

The Steam Genie HydroGenie 1 had two 3M Sutorbilts in series, with the secondary blower running at 91% of the speed of the primary. The HydroGenie 2, which was a contemporary unit to the HG1 had a single 3M blower. Both units were powered by the same 20HP model CCKB Onan engine. As such, you had a fair apples/apples comparison of a dual blower, versus a dual blower setup. The dual blower setup had a significant CFM increase, and a marginal lift increase, but the lift increase was not utilized, as both units had identical relief valves set to the same spec.

Now, the question....Was the CFM increase worth the extra cost. In retrospect, probably not. However, one must understand the reasoning here. First, in the day that the HydroGenie 1 was being developed, Sutorbilt was just awful covering warranty. At that time, Roots and Tuthil were not players in the Truckmount market. Sutorbilt had a "sellers market', for the most part and it was quite ordinary to decline a warranty on the slightest transgression of either the user or the TM builder. As such, overdriving or using a blower beyond rated lift was "verboten", and Steam Genie would never think of using a 3L blower for greater CFM whilst still running at a 14"-15" of lift, which would guarantee every blower warranty to be voided. A novel solution to capture a few lost CFM, while also garnering a perceived (purely marketing) advantage was use two blowers in series, just like the portables that Steam Genie had pioneered in a day when nobody was "stacking" portable blowers. The net result of using dual TM blowers in series was arguably 10% for performance and 90% marketing in a day when you had the blower manufacturers (just one in this case) having quite a bit of influence on design.

Today, I can't see any good reason to use PD blowers in series. In parallel, that's a different story.

 

[Desk Jockey]

Shawn we lost a blower on our Hydrogenie once and ran it with the single until we got the replacement. It did fine, a little louder but still cleaned.