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fhorst · 12-01-2003, 04:04 AM

I want to start a discussion about pumps.

Most of us use aquarium pumps, which are made for "normal" usage. A few of us bought an expensive Iwaki pump, which is made for High Head.

There is a nice graph, where all the pumps are http://www.procooling.com/~phaestus/temp/flowcurves.jpg and from that graph, we can see that the MCP600 is "the best".

I have not seen a discussion on why that one is the best, or why one pump is better than the other one.

First some theory:

The function of the pump's motor is simple: outside magnet and inside magnet. The outside magnet will due to the power (220v) become a north or a south pole magnet. The inside magnet will move due to the pole change. (50 or 60 Hz)
Or as Iwaki tells it: "The drive magnet is magnetized barium ferrite for 4-, 6- or 8 poles. It rotates the impeller by using the magnetic field from the outside of the rear casting

No brushes, so nice silent, and long lasting. Downside is that it is a weak motor.

All motors seem to run at about 3000 Rpm.

The motor is connected to the impeller:

So, what makes the head? And why?

As far as I can see, when a pump comes to its max head, the pressure is to high for the impeller to turn around. Actually, as I stated, the motor is weak, and it first will "slip", missing a few pole changes and finally will stand still. (With a bigger motor, having bigger magnets, this will take longer, and therefore give more head)
When the pressure drops the impeller starts moving again, till the pressure is again at the top. This goes fast, so you won't even notice. Except that there is less water flow.

From the Iwaki website, we can see that the pump motors stay the same, but they change the impeller for “Normal usage” high Head, or High flow.

This got me thinking: what if we modify the impeller of our “Normal usage/High flow” pumps? Simply look at the High head design. The impeller wheel is a bit bigger, and has no fins. The impeller housing has changed also, but still……

If my theory is correct, all we need to do is to take the impeller, and take of the outside of the impeller fins, (cutting it diagonal). This will kill our free flow rating, but it should improve our head a lot. And for water cooling, we are not interested in free flow, but in head… That’s why the 600 l/h MCP600 pump out performs a 1400 l/h pump. We are having only a 5 l/m in our setup.. (300 l/h)

Please share your ideas and theories.

12-01-2003, 04:04 AM	#1
fhorst Cooling Savant Join Date: Oct 2003 Location: Almere, The Netherlands (Europe) Posts: 262	Pump mod for High Head I want to start a discussion about pumps. Most of us use aquarium pumps, which are made for "normal" usage. A few of us bought an expensive Iwaki pump, which is made for High Head. There is a nice graph, where all the pumps are http://www.procooling.com/~phaestus/temp/flowcurves.jpg and from that graph, we can see that the MCP600 is "the best". I have not seen a discussion on why that one is the best, or why one pump is better than the other one. First some theory: The function of the pump's motor is simple: outside magnet and inside magnet. The outside magnet will due to the power (220v) become a north or a south pole magnet. The inside magnet will move due to the pole change. (50 or 60 Hz) Or as Iwaki tells it: "The drive magnet is magnetized barium ferrite for 4-, 6- or 8 poles. It rotates the impeller by using the magnetic field from the outside of the rear casting No brushes, so nice silent, and long lasting. Downside is that it is a weak motor. All motors seem to run at about 3000 Rpm. The motor is connected to the impeller: So, what makes the head? And why? As far as I can see, when a pump comes to its max head, the pressure is to high for the impeller to turn around. Actually, as I stated, the motor is weak, and it first will "slip", missing a few pole changes and finally will stand still. (With a bigger motor, having bigger magnets, this will take longer, and therefore give more head) When the pressure drops the impeller starts moving again, till the pressure is again at the top. This goes fast, so you won't even notice. Except that there is less water flow. From the Iwaki website, we can see that the pump motors stay the same, but they change the impeller for “Normal usage” high Head, or High flow. This got me thinking: what if we modify the impeller of our “Normal usage/High flow” pumps? Simply look at the High head design. The impeller wheel is a bit bigger, and has no fins. The impeller housing has changed also, but still…… If my theory is correct, all we need to do is to take the impeller, and take of the outside of the impeller fins, (cutting it diagonal). This will kill our free flow rating, but it should improve our head a lot. And for water cooling, we are not interested in free flow, but in head… That’s why the 600 l/h MCP600 pump out performs a 1400 l/h pump. We are having only a 5 l/m in our setup.. (300 l/h) Please share your ideas and theories. __________________ If it get's hot, it needs to be watercooled! Last edited by fhorst; 12-01-2003 at 04:10 AM.