PTS Flowbench Forum

Hi, I m a new owner of the blueprint from Bruce. I live in Canada and I have a hard time to find cheap vacuum engine. 1 option that I found is the ametek 116668-50 for 85cad http://ca-en.alliedelec.com/ametek-lamb ... /70252300/ . Can someone can help me finding a cheap opion from Canada. Also how many motor do I need for 600cfm? Thank you

Welcome to the Forum Daoust,

According to the specifications, each motor should produce only about 30 CFM at 44 inches back pressure.
Actual quoted figure is 32.9 CFM at 43.8 inches.
To reach 600 CFM in practice, probably at least TWENTY motors would be required !!!
These particular motors are quite small, and far more efficient at low pressure, just not suitable for a flow bench.

Each motor draws 3.5 amps and only produces 30 CFM at flow bench pressure.
That is around 8.6 CFM per amp which is pathetic.

The normal efficiency range expected of common vacuum cleaner motors falls between 8 and 16 CFM per amp, with 12 CFM per amp being pretty average performance.
8.6 is piss poor, it does not get much worse than that.

Try to be patient, you will find something much better.
A lot more air for fewer amps, and a lot less dollars.

Just to put all this into perspective, twenty motors would need at least 70 amps to produce 600 CFM, probably closer to 80 amps at 240 volts.
Motors at the top end of the efficiency range would need about half that supply current.
Most of us are power limited, and that is what usually stops the fun as far as chasing highest possible CFM.
Critical to this is motor choice.

Many people here have motors capable of 16 CFM per amp, if you are limited to say 35 amps supply, that might get you around 560 CFM or slightly less.

thank you very much .

You are most welcome.

Sourcing motors can be tricky, because good deals come and go, and shipping overseas can be expensive. What is available right now may be all sold out in six months time. Its not really much help asking here on the Forum, because most of us here are just not looking around for good deals on motors right now.

You may get lucky if someone on here located in Canada spots something, but you will probably have to do your own searching for motors in your own part of the world. Any motors, 220v (American) 230v (European) or 240v (Australia) will work for you, and it does not matter if its 50Hz or 60Hz. In reality they are mostly all now made in China and all exactly the same.

One of the Ametek motors most commonly used in flow benches is the 115923, it has one more favourable flow characteristics. This is going back a few years but, I managed to find them for a reasonable price just by calling around to a few local vacuum cleaner repair shops.

Just had a look at the Amtek 115923, its a 120v motor, but there is also a 240 volt version available, 116278-01:
http://www.centralvacuummotor.com/motors.htm

Data sheet:
http://www.alliedelec.com/m/d/1ec82d83b ... 32b8e1.pdf
Now this is for the 120v version.
But the 240v version should run at half the current.
I very strongly recommend you stick with 240 volt motors and not try to run two 120v motors in series.
According to the specifications, 44.3 inces, 84 CFM and 5.25 amps (at 240v).
That is 16 CFM per amp, and Olympic gold medal performance.

You will probably need eight motors to reach a genuine 600 CFM, but its doable.at around 40 estimated amps.

Tony wrote: I very strongly recommend you stick with 240 volt motors and not try to run two 120v motors in series.

Tony, Daoust is in Canada, Canada like the U.S. has 120v available from the mains so, he would not have to run the 120v motors in series.

Ah, thanks I did not know Canada used the US power system.
Then either 120v or 240v motors would be fine if they have a direct connection to the appropriate supply.

But its still a bad idea connecting motors in series, so definitely avoid that.

Thank you for your help

At first I did not understand that I need to know the cfm rating at 44wc, now it make sense for me so it will be easy finding something now that performe like my needs.

for the different compagny like, ametek, Dyson, Panasonic, if they all are ball bering and the flow chart is good for my needs, is there some brands to avoid for durability?

Thank you again

All of these motors are mass produced down to a competitive price, and they are for consumer products with planned obsolescence in mind.
Definitely not military or aerospace quality !
But reputable brands with ball bearings are still pretty good motors.

Just build your bench in such a way that changing out a motor is not going to be an all day job.
The biggest enemy of these motors is heat and wear (of the brushes and commutator). One big advantage they have in a flow bench is that with a motor speed controller they will very rarely be run at full flat out voltage and speed for any length of time. Also the motor cooling air is much cleaner than it would be in a vacuum cleaner. So motor life should be excellent.