pump related electrical question..

Howdy...I have a pump question. I've got this iwaki pump that's just very beastly and also a Comair Rotron Fan (190mm) that makes a lot of noise. I know from doing the 12 to 7v mod that you can tame noisey parts...could something like this be done to a water pump that plugs into a wall jack (110v).

Thanks for any help..im completely oblivious about electrical stuff.

_Siph

Which Iwaki do you have, because the 15 series isn't loud...

ahh...this is a MD-70...long story though..it wasn't something I went out and sought, it was acquired with some other equipment at a great price!


The pump's actually not THAT loud but the fan is..

I was even thinking if I could do something with like a Light switch dmmer maybe..

Siphilon said:

Howdy...I have a pump question. I've got this iwaki pump that's just very beastly and also a Comair Rotron Fan (190mm) that makes a lot of noise. I know from doing the 12 to 7v mod that you can tame noisey parts...could something like this be done to a water pump that plugs into a wall jack (110v).

Thanks for any help..im completely oblivious about electrical stuff.

_Siph

Click to expand...

ummm ... you can decrease voltage to slow a DC fan or pump, but that does not work for AC motors (e.g. lamp dimmer circuit). Lamp dimmers work on AC because light bulbs have a purely resistive load characteristic ... this is not the case with AC motors. Simply reducing voltage to an AC motor will increase current draw to a point, then it will either quit working or burn out. AC motors change speed based on their design and the AC frequency used to power them ... e.g. a 60 Hz pump motor will run at 5/6 speed if operated at 50 Hz (typical European AC frequency). An AC frequency converter is an expensive option to say the least, but it can be done ... you simply vary motor speed with a frequency change. A typcial 60 Hz AC motor will usually be OK from about 20 Hz to about 120 Hz ... the speed change will be linear with frequency.

On the other hand, I've heard Iwaki now has a 12VDC pump ... that would change speed with voltage, but, of course, you'd need to swap yours out for one of those. Good luck with that!

KK

Right. An AC dimmer switch may *look* like a normal DC potentiometer, but it's actually a lot more complicated than that. It has to do with (my crappy explanation) cutting off the sine wave at various intervals so the motor is actually 'pulsed' instead of constantly ran. This works great at low RPM motors like a ceiling fan, but on thos massive Comair fans, it doesn't work as well. If a ceiling fan would run at 10%, your big fan just simply will not. It won't even start spinning until you've got your dimmer at probably 60-70%.

Just the same for a pump, except there is typically even more resistance so the pump would hardly run at all unless through the highest 'dimmed' settings.

Wow...what a great reply, thanks a lot vonkaar & KooolerKing. Guess I'll just get some ear plugs!!!

But seriously thanks a lot for the information. very helpful.

I only know this because... well... look:

I was doing a similar thing last night (comair fan too, crazy, no?) and I saw the whole 70%+ anomoly... so I talk to the 65 year old electronic engineer guys at work and they explain what happened =p. I'm probably way off on the EXACT answer, but it's close enough =p.

I guess the only other thing I can suggest is to find some sort of sound-absorbing enclosure. Make yourself an external box and try to sound proof the whole she-bang. If you can't silence the components, cancel out their sound. That's what my great-great-great-grandfather used to say about CPU-Water-cooling.

Just for interest sake here is a tiny little blurb on adjusting an ac pump. You can adjust an AC pump BUT there not for a water cooling situation.

In the industral setting you have a pump, then you have to make the pump turn and that is with an electrical motor. These motors come in 2 flavors, a constant motor and a VFD compatable motor.

The VFD (variable frequence drive) is an electrical box that adjusts the electrical characteristics feeding the motor. This adjustments can speed up or slow down the motor, thus adjusting the speed and the flow of the pump.

A cheap VFD motor it about $2K and the VFD is about $5K. and then you need the pump. Also, typically, you need 3 phase power to operate this.

This is just for knowledge sake, nothing really that we in the watercooling world can use

wow...lotsa info. I'm gonna use a external box type setup and sound proof it as best as possible.

vonkaar, that comair rotron fan looks exactly like the one I have.

If pump is submersible, make it work underwater with good accoustic insulation.

Anyway it's possible to limit AC power using NPNP semiconductors (I don't know if in english they're named other than TIRISTOR).
Anywy they work this way - no power until impulse is given to specified place and electricity remains till there's a voltage (voltage is sinusoidal so it drops to zero 60x per second on 115V instalation). So with proper tiristor timing youc can achieve any power without limiting voltage. these parts don't produce so much heat. They're used in for example electrical powered vehicles - like trains, but also quite much part of house electricial stuff with settable power should work this way.

Anyway I suggest contacting some electricial engineer / shopper, to get parts and make power adjuster.


Resistors are out of discussion.

vonkaar said:

Right. An AC dimmer switch may *look* like a normal DC potentiometer, but it's actually a lot more complicated than that. It has to do with (my crappy explanation) cutting off the sine wave at various intervals so the motor is actually 'pulsed' instead of constantly ran. This works great at low RPM motors like a ceiling fan, but on thos massive Comair fans, it doesn't work as well. If a ceiling fan would run at 10%, your big fan just simply will not. It won't even start spinning until you've got your dimmer at probably 60-70%.

Just the same for a pump, except there is typically even more resistance so the pump would hardly run at all unless through the highest 'dimmed' settings.

Click to expand...

Good point ... I had not considered that aspect. I think some older lamp dimmers are resistive, but now that you mention it, I'm guessing the new ones, such as fan speed controllers, could "chop-up" the AC sine wave. Again, the trouble with that is the motor no longer sees a "clean" AC wave and may act strangely. The other down side is that the sine wave chopping lamp dimmers generate a ton of electrical noise and radio interference ... place a radio tuned to an AM station in the same room sometime and listen to the buzz it creates. Maybe your computer will filter that out, maybe not, but who needs to deal with that issue?

Good Luck,

KK

Ac motors are inductive meaning if the voltage decreases it will draw more amps to turn at its rated rpm. This means heat buildup and premature failure. Like said above you can change the frequecy to lower your speed but Ac speed controls are more exspensive than a new pump.

It won't even start spinning until you've got your dimmer at probably 60-70%.

Click to expand...

Once it starts spinning, it can be turned down and continue to spin.

Not very well. See picture above =p. Past about 50% it just simply does not pulse fast enough to keep up with those heavy blades. It eventually dies out. It may work for smaller plastic fans but not with a heavy duty comair rototron. If you've ever held one at full tilt, you know what I'm talking about. It moves more air than my 18" box fan.

You can research this baby, I'll just provide the link.Speed control

This one is cheaper but it look like a fire hazard. Link

That's pretty sweet... I wonder what the schematics of a circuit like that would look like... 10 amps is pretty freaking overkill, and that's probably a good portion of the cost. If something suitable exists for 1/10th the price, or if the components to build a comparable circuit are cheap... it might be a fun project ^_^.

Also... the 'check with motor manufacturer before using' footnote to the catalog page is somewhat concerning. It mentions horsepower, but not RPM or applications. Still, definitely worth doing some research on =p.

Components would be far cheaper, so as I suggested before - if you have time, youc could ask someone who knows a bit on electronics to give you scheme, then to make such thing by yourself.

It all depends on whether you fan motor is strict AC or AC/DC.

Most DC motor (except those using perm magnet as poles, i.e. model car motor) can run with AC power with reduced efficiency, so are also called AC/DC motor. They have VERY strong torque on power up and thus make ideal motor for electrical tools like drill, grinder, blender and saw. Their rated speed mostly depends on input voltage and number of poles, affected very little by AC frequency. More poles, more torque but lower RPM, principle apply to AC motor as well.

Strict AC motor using different principle to run. They have very weak torque especially during power up. In fact they can't even start rotating without some external aids. AC Motor RPM depends on AC frequency and the number of magnetic poles. For example, a 2-pole AC AC motor accepting 50Hz will have theoretical RPM of 3000RPM (50Hzx60s), and realistic RPM closes to 2900RPM. For 4-pole AC motor with same AC power the RPM will be 1500RPM theoretically. AC motors mostly use in task when torque is not important, because they are cheaper and last longer than DC motor. AC motors are used in everywhere outside powered tools.

Luckily, only bigger fans use AC motor. 12cm fans are small and they happen to use mostly DC motor which accept AC power as well. You are cut the voltage with transformer to silence a loud 12cm fan. I'm using an 0-250V adjustable transformer for my loud 120x120x38mm NMB fan, dropped the voltage from 220V to 150V, it's now inaudible. The transformer itself costs more than then fan though. An alterntive will be to go for external DC route. Get a adjustable DC transformer which let you choose among 7.5V, 9V and 12V, and get a powerful DC 12cm fan. It's probably cheaper and easier to do than AC fan route.


Correct me if I'm wrong.

Probably another piece of useful information. There is one easy way to identify brushless DC/AC motor, brush DC/AC motor, and strict AC motor.

Strict AC motor can produce aweful interference with CRT if putting too close, make screen shaky. Brush DC/AC motor interferes with CRT with many snow spots, while brushless DC/AC motor produces no visible interference.

conclusion:
CRTs are perfect pump testers