RE: Pump Cavitating...

[Sneakers O'Tool]

So, i've looked through the forum and can't find specifically a thread about getting air introduced into the lines during pumping from kettle to kettle out. We have a Brutus setup, with two march pumps and the corrisponding SS quick disconnects to make it all work. We've read to make sure the inlet of the pumps should be on the bottom and output on top. We've also been advised to buy an inlet ball valve with a bleeder valve built in. Two things: Where can i buy a SS ball valve with a bleeder ( have only seen them in bronze or brass) and second, what else can i do to eliminate the air getting introduced into my lines? either purge or prevent... Thanks in advance

[BadRock]

There was a similar thread here about a year and a half ago. The verdict was that the air was getting introduced at the SS disconnect.

[Kbar]

Meter the outlet of the valve, not the inlet. Valve the inlet to make disconnects, but never meter the inlet to any pump, positive or non-positive displacement. As for bleed valve, simply make sure the inlet of the pump is always flooded, that is, positive pressure on the inlet due to gravitational advantage. Put the pump below the Pot/Tun/HLT, as I believe most stands are, especially the Brutus. You will cavitate if the inlet pressure into the pump falls below the vapor pressure of the wort/water/etc.

I only have a 12" head (0.434 Psi) on my pump inlet, no issues. I did make sure to have the inlet below the outlet - pump head orientation.

Happy Brewing.

[BeerPal]

Here's how I configured mine. Solved my cavitation problems and works great:



The bottom is the "in" side, the top is "out". The horizontal valve is the bleed and the vertical valve controls the flow to where ever. To prime, I simply close the flow valve and open the bleed until I get a good flow out of it (just takes literally an ounce or so at most.) Then I close the bleed valve and open the flow valve. Since I started doing this, I have had zero pump problems.

[Mylo]

If you still get cavitation after doing a setup like BeerPal and purging, then you have a slight air leak on the inlet side of your system. I sanitize my pump and hoses during the last 20 min of the boil. During that time I have slight cavitation, because the pump is sucking in vapor from the bubbles at the bottom of the boiling kettle. After the flame is off, it's smooth sailing.


Mylo

[ajdelange]

This may or may not be a factor but I've noticed "cavitation" when pumping boiling or nearly boiling liquids with these little centrifugal pumps. What is actually happening is that the slight reduction in pressure in the involute is causing the water (this is where it happens to me) flashes into steam. A quick spray of cool water on the involute (bronze in this case) every few minutes keeps this from happening. Obviously if you find gas at the delivery end of the output hose it's not steam that's involved and you can disregard these remarks.

[Quin]

There was a similar thread here about a year and a half ago. The verdict was that the air was getting introduced at the SS disconnect.

+1 Remove an inch of hose at each end and redo connections. It worked for me.