Problem is with getting these 12v custom pumps done is you need to order a boatload, IIRC at least 250 units for Iwaki to even consider it. Who is gonna lay out that kind of cash? I think they would run about $175 - $200 a piece too.

Not really. It is a big issue with Iwaki to modify these down to 12vdc as Nikhsub1 says. This is what they responded: "In addition to the change in the windings, the pump's circuit board would need to be reworked to accommodate a 12VDC design. The change in voltage and circuit board amounts to a complete redesign of the pump; therefore, we are unable to offer the RD-30 or RD-20 in this configuration."

Next week when I have more time to concentrate on this instead of my job I'll research a few more possibilities. One is finding a cheaper/smaller 12vdc to 18vdc (for the RD-30) or 24vdc (for the RD-20) voltage converter to be able to run off of a standard PSU. This would also allow it to be moved where ever there is room in a box.

The other is to take a sample pump to a guy I know in Phx, next time I'm there, that may be able to modify (redesign) these and see if cost will permit a large run.

Did you by any chance ask what RD-20/RD-30's cost when a large amount is bought?

Yeah I did, but you need to get those through a distro, not directly from Iwaki. I think if 100+ units are ordered, 25% discount. So the RD-30 which goes for $275 is $220 and the RD-20 IIRC is $250 for $200. Not cheap.

Was browsing through the RD PDF, and applying the centrifgual pump laws.

Basically what we'd be asking from Iwaki is an RD-20 that spins at 2900rpm (@ 12.0v).

Sure, it's not going to happen, but it's nice to dream.

The only moderate draw-back to this though is that the Iwaki pumps aren't that quiet. They're not horribly noisy either, but they're certainly not "near silent".

hmm - surely the easiest way to get an RD-20 that spins at that speed at 12V is to use a step-up transformer to raise the 12V to the required voltage? (or indeed a dedicated supply at the required voltage since people may not wish to draw on tehir PSUs 12v rail(s)..)

Total pump power draw would be ~20W or so, so given a step-up transformer efficiency of ~80%, we're talking about a 25W power draw from a PSU 12v rail, which is nothing.

Yeah, the easiest way to do it using existing equipment is to use a step-up transformer and an existing Iwaki RD-20. Would be nice if the transformer were not needed though.

Depends - are we interested in getting such pumps made up and done right and running off a 12v rail, or are we just looking to skirt around the limitations and put together an "ideal pumping characteristics" kit?

Either way, it'd probably cost the end-user about the same. i.e. existing pump + transformer, as opposed to custom pump production run rewired for 12v native.

Well here is what I found out this week. I talked to an engineer at Iwaki and he said they will most likely NOT ever create a 12vdc model. It is a small market to them relative to the other pumps they sell let alone the design costs involved.

So, I have a long time friend that owns a large water purification manufacturing plant and they happen to be an Iwaki dealer. If the volume is high enough (100) I can probably get these (RD-30) down to about $210 each maybe more if we get higher interest. But as stated before that's a lot of cash outlay. I'll be testing some 12v stepper transformers once I receive my test RD-30. I have also ordered an RD-20 but it is back ordered for 4 weeks.

Cathar, given this situation what voltage do you see would be ideal for a stock RD-20? 22vdc?

21.0v for the RD20 should give the desired 2900rpm.

Mathematically it works out to 20.8v, but 21.0v is a pretty fair approximation.

Okay, thanks. I'll post with updates.

They arrived! I have 6 RD-20s and 6 RD-30s. With my friend's volume account I can get the 100 qty volume discount at 6 qty at a time.

They are both very quiet, about the same noise level as my Silver Stone ST40F PSU fan. Very well made. When testing I noticed that they both were compressing the inlet hose (Clearflex 1/2", 1/8 thick). I've ordered the Clearflex 5/8" which should do the trick. The RD-30 has noticibly stronger suction though.

http://img363.imageshack.us/img363/4448/IMG_0395.th.jpg

http://img363.imageshack.us/img363/113/IMG_0399.th.jpg

Will you be selling the rd-20's? If so I would be interested.

Yes,

I will let them go for a little over what I paid for the remaining 5 each of the RD-20s and RD-30s I have. I'll offer them to ProCooling readers first.

RD-20=$187 money order if via PayPal add $7.50
RD-30=$205 PayPal add $8.20

Plus whatever shipping is desired.

Thanks,

Mike

As always happens with me, as soon as I complete an order elsewhere, what I originally wanted becomes available. I already have a pump on it's way, the Panworld PI-30Z. Otherwise I'd jump on this. Great deal on great pumps!

You do realize that transformers only work on AC power, right? In case you do know what you wanted but accidentally confused some others along with me, what is needed is a DC-DC power supply.

Yes, transformer for wall (AC) to pump (DC) and a DC-DC voltage converter for use with the computer PSU.