MD-30RZT Cavitating

I just put together an external box with a Iwaki Md-30RZT, Criticool Waterplant res, and 2-342. Unfortunately, I think the restriction of the inlet by the barbs on the Waterplant is causing the pump to cavitate because it is extremely loud (I can hear it throughout my house), bubbles are coming from the outlet, and when I throttle the outlet the pump gets quieter. To remedy the situation, I ordered from mcmaster a 2'' OD 1.5'' ID clear acrylic tube and clear acrylic discs which I will fashion into a res that will fit directly over the pump inlet. The other end of the new res will be a 1/2'' od barb. Should this be sufficient in preventing further pump cavitation? Also, what should I use to seal the area around the new barb and the pump inlet in the new res, and what should I use to bond the acrylic.

It's loud? That's odd... I always thought Iwaki's were some of the quietest pumps available. You might want to think about returning it for a replacement (unless u bought it off ebay, which in that case I suspect is the reason the guy sold it).

Cavitation doesn't cause bubbles. Sounds like you just have air in the system. Air can definitely cause noise. You might also have a mechanical problem. Is it a new pump or a used one?

It's used. Are you sure cavitation doesn't cause bubbles? Regardless, I gooped a res to the inlet of the pump for less restriction. Will tell you how it works out when it dries.

Moony349 said:

Are you sure cavitation doesn't cause bubbles?

Click to expand...

Cavitation is actually a very complex subject. A very, very simple definition is some situation within the pump that causes a pressure drop so severe that the liquid vaporizes. Those vapor bubbles immediately collapse, and with such force as to damage the pump by causing a pit in the housing or on the impeller. The “bubbles” are actually little vacuums, which is why they collapse violently enough to make a dent in iron. There are no air bubbles formed by this process.

Take the pump apart...there might be something obvious.