240 volt vacuum motors - fan search.

[ivanhoew]

gosh ,they came out a bit big.. oh, incidentaly the wheel is approx 10 to 12 inches dia .regards robert.

[larrycavan]

[riga team]

[Tony]

Those blowers look pretty good.

The flow path looks sufficient for several hundred CFM, but the rotor outside diameter means that some fairly extreme Rpm will be required to generate sufficient pressure.

I know that an 18" rotor develops around 17" at 2,850 Rpm.

So a 12" rotor would need to be going at 4,275 Rpm to develop similar pressure at a similar tip velocity.

Pressure goes up as Rpm squared, so to double the pressure, Rpm x 1.414

32" pressure will need approximately 6,000 Rpm. It should work, if the aluminium rotor does not fly apart at that speed.

[Thomas Vaught]

Quote:

"Superflow benches use a 110v 115923 motor. The Superflow site says a SF600 has 8 motors and requires a 37A Single Phase 240v.

Correct!

"The Pro Bench uses 16 motors and requires 75A Single Phase 240v."

The SF1200 has 16 motors, the ProBench uses 12 motors according to Harold B.

"I also checked the FlowData site and they use 8 motors in the small bench and require a Single Stage 50A."

Yep.

"I've read on the forum you can wire these motors in series, two at a time. So, with this style brush motor, a 110v, you can run it at 240v to cut the amps in half? Each motor is rated at like 11 amps. I think this is what I'm reading."

E=IR

"Anyone have a clear drawing of how to do this? Do you need all the relays like the article bench?"

Most of the SF benches use motor controllers these days. SF uses ONE high amperage relay to turn on the power to the motor controller.

If you are not using a motor controller you need
a way to handle the high amperage that each motor draws on start-up. A relay system is designed for that high amperage condition vs a typical toggle switch. Use the toggle switch to control the relay.

A couple of the SF benches are using the 4 wire circuit. Most in the past did not. If you do not completely understand the electrical side pay a electrician to help you vs potentially having a serious accident or fire hazard.

JMO

Tom V.

[cspeier]

I would never attempt to re-wire this bench. I have a friend who is an electrician. I just want some info so I could make sure he's doing it right

Thanks Tom

Chad

[ivanhoew]

tony,thanks all for the input ,ill have a look in detail at that aluminium wheel today to see if i think itll fly apart at 6k ,tom ,any chance of a schematic of this red black green white etc system , i recognize the inherant risks involved in the possibility of a 110 motor recieving 220 v ,if the 1st motor goes down,also the fascinating possibility of a 12'' wheel grenading at 6k sound full of intensive care possibilities,and due caution is observed at all times ,i wonder if your assuming a 3 phase system here ? regards robert.

[ivanhoew]

ah , i had a bit of a root through all the stuff in here ,and i know understand the 4 wire system ,the reason i didnt get it is that in the uk ,we only have a 3 wire domestic supply brown 230volts ,blue neutral,green/yellow earth .so i dont have that option.i didnt realize that in the us there is this system ,sure makes it easy to run 110 or 220 with out difficulty.regards robert.

[Tony]

The four wire system (three phases) (neutral)(plus ground) is the usual system used in most countries, but it is far from universal. America has some rather unique and unusual systems not found anywhere else.

Unless you know what you are doing, it is always prudent to get some expert advice from a local electrician. The problems with international Forums such as this one, is that many of us have radically different electrical supply systems, and advice may not always be relevant, or just plain wrong in your particular location.

[ivanhoew]

i agree tony we all tend to think everybody must have the same system ! heres a pic of the fan ,it is balanced with machined dimples on the back ,any info on possible rpm would be appreciated !regards robert.

[riga team]

http://www.domel.si/default.asp?lpage=1&lang=en 110 and 220 volt vacuum motors

[Tony]

Robert, there are some issues that worry me a bit about that fan rotor. The main one is that the blades are only supported along one side. Centrifugal force plus air pressure is going to try to tear out the blades from the supporting disk.

The other difficulty is that aluminium fatigues very easily. It may run for a while, and then start to crack around the roots of the blades. It only has to toss one blade, and the unbalance will destroy the whole thing in an instant.

All the commercial high pressure rotors I have seen have been constructed from two flat sheet steel disks, with fairly short straight radial blades arranged around the outer periphery. Curved blades are never normally used with high pressures.

A successful homemade rotor would be well within the capabilities of most of us here with simple hand tools and a bit of care. I have two commercial rotors here that look surprisingly crude in construction. Unfortunately I still do not have a digital camera, but hopefully soon I will be able to give you guys some pictures, dimensions, and test results. I am convinced this holds more promise than a bunch of vacuum cleaner motors.

Anyhow, curved blades have some interesting characteristics. Forward facing blades (leaning into the direction of rotation) will give an almost constant pressure over a surprisingly wide range of flows, which can be very useful for us, but drive horsepower varies hugely with mass air flow. If you blank off the flow to zero, pressure hardly changes, and motor power falls very low.

Rearward curving blades have a far more constant drive power requirement, but pressure will fall off rapidly as flow increases. That also can be useful for some applications because the motor cannot be overloaded, but for a flow bench, the test pressure would be much more touchy to keep constant. With rearward curving vanes, blanking off the flow to zero would cause a very substantial rise in pressure, and motor power would remain fairly high. That is not ideal for us either.

I believe many vacuum cleaner motors have rearward facing blades which is ideal for a vacuum cleaner. Very high suction at low flows, and the motor will not be overloaded at maximum open flow. Perfect for a vacuum cleaner, not so good for a flowbench.

You see figures like 100+ inches of water at zero flow, and ten inches of water at 80 CFM. The pressure just fades away to nothing as flow volume increases.

A large diameter straight bladed rotor might be something like 50 inches of water at zero flow and 45 inches of water at 500+ CFM. A much more constant pressure versus flow, and much more user friendly in a flowbench.

[Thomas Vaught]

I have a 115923 Super Flow type Vacuum Motor apart. It is a two stage unit.

The impeller has two parallel flat steel discs, as Tony mentioned, that are 4" in diameter. (The drum is about 5.7" in diameter). The opening hole in the first plate is 1.750 inches in diameter.

The Plates are 3/8" apart. The impeller blades are curved and the curve is in a clockwise direction.

The second stage is just like the first stage.

Making a impeller scaled larger from the 115923
specs would be easy to accomplish. Even a two stage unit.

Agree with Tony on this one.

Tom V.

[ivanhoew]

thanks tony and tom ,that replicates my thinking on the integrity of this wheel,it struck me better to try something else before something actually struck me!.now thinking that making my own double disc impeller may be feasable,and putting it into the ally casing from this wheel ,i do have a concern that the torus being made of ally might just break though ,it not being very thick walled ,id estimate 3 to 4 mm...any pictures you or tom can provide to illustrate the impellers discussed would be very instructive .regards robert.

[Jesse Lackman]

I like the idea of building a blower. If it the sides could be drawn in CAD it could be imported to a waterjet cutter which could cut "slots" for the blades which could then be TIG welded into the sides.

There is a waterjet cutter here, they charge 100/hr but could cut a lot of sides out of thin metal in one hr.

I'm had them cut a couple torque plates out of 1.25 steel, that thing does a beautiful and precise job.

I haven't had a 923 apart, how is the staging done?