Riptide pump cavitation i

[ImperialDrHops]

I recently added my first pump, a riptide, to my brewery. I did a test run with water and it was very loud, but it worked. At that point I didn't know the loudness was abnormal. When I brewed my first batch the pump wouldn't work. It was loud and the wort wouldn't pump through the outlet. Nothing worked. The wort just pulsated back and forth a few inches in both tubes.

So instead of a recirculating mash, it just rested. After the boil, I tried the whirlpool to see if the pump would work and viola, it did! I did nothing different but it worked. And extremely quite too. I realized at that point what it was supposed to sound like. After the whirlpool I switched the hose to the cfc and bam, pump went back to pulsating the wort back and forth, never actually moving it anywhere. I switched the hose back to the kettle and the pump worked again. So I finished the batch without using the pump and contacted Blichman.

They said I had all the right parts and that it was cavitation. Possibly an air leak from loose connections. I'm using quick disconnects and not sure how to test if they are loose. I tried a test again yesterday with water and nothing worked. All the same issues. I tried adjusting the pump head but still nothing. First time I had inlet on right and outlet on left, and second time reversed this.

Does anyone have any ideas on what I'm doing wrong or how to fix this?

 

[day_trippr]

The fact that it worked at one point - and quietly - indicates cavitation.
You really need to fill the pump head plus have sufficient water volume immediately up-stream in your hoses to not promptly suck air into the pump head when you turn the pump on.

For orientation, make sure the inlet is either below the outlet or on the same plane, so air will flow out from the pump head when fluid enters...

Cheers!

 

[Vale71]

This has nothing to do with cavitation which would cause the pump to work regularly but be much more loud than it should be.

The fact that the wort is just pulsating but not flowing shows that you have too much constriction upstream most likely from the grain bed.

 

[matt_m]

Definitely sounds like air. If you don't have the line from your vessel to the pump inlet completely full of liquid its not going to pump or its going to pump until the first air pocket hits the pump head. When mine does what you describe I find that I need to start and stop the pump a few times and let the air work its way back into the kettle. Sometimes more than a few. My kettle-pump hose is short and nearly a straight shot. If its long or has a low point lower than the pump I'd think that would further compound the situation.

It primes easiest when I first open a valve downstream of the pump, open the valve on the pump 100%, then open the valve on my kettle. Any air then escapes the downstream side and then I make final connections and adjustments before turning on the pump.

The purge valve on the pump head doesn't seem to be very effective since the pump is at the low point but maybe I just don't know how to use it. And anyway, it spews sticky wort everywhere.

 

[ImperialDrHops]

The fact that the wort is just pulsating but not flowing shows that you have too much constriction upstream most likely from the grain bed.

This pulsating happened with wort and water. So it has to be another issue.

Definitely sounds like air. If you don't have the line from your vessel to the pump inlet completely full of liquid its not going to pump or its going to pump until the first air pocket hits the pump head. When mine does what you describe I find that I need to start and stop the pump a few times and let the air work its way back into the kettle. Sometimes more than a few. My kettle-pump hose is short and nearly a straight shot. If its long or has a low point lower than the pump I'd think that would further compound the situation.

I'm starting to think my kettle isn't high enough over the pump and with too much tubing laying on the ground not enough liquid is filling the inlet tube. It's currently sitting on a propane burner about a foot off the ground while the pump is directly on the ground. I am going to try moving the kettle onto my stainless table while keeping the pump on the ground.

It primes easiest when I first open a valve downstream of the pump, open the valve on the pump 100%, then open the valve on my kettle. Any air then escapes the downstream side and then I make final connections and adjustments before turning on the pump.

The purge valve on the pump head doesn't seem to be very effective since the pump is at the low point but maybe I just don't know how to use it. And anyway, it spews sticky wort everywhere.

I opened the riptide valve 100% and then opened the kettle valve 100% and water and wort would flow all the way through. On next attempt I will check to make sure there is no air in the inlet tube. I agree the purge valve is frustrating because sticky wort just goes everywhere. I can't imagine that's supposed to be used often.

 

[Vale71]

First time I had inlet on right and outlet on left, and second time reversed this.

Does anyone have any ideas on what I'm doing wrong or how to fix this?

Can't figure out how I missed this the first time. You can't reverse the connections at will as this reverses the direction of flow. This is a centrifugal pump, the inlet is the one going to the center of the head and the outlet is the one going out radially from the pump head. On the riptide the outlet is the one with the built-in valve.

 

[ImperialDrHops]

Can't figure out how I missed this the first time. You can't reverse the connections at will as this reverses the direction of flow. This is a centrifugal pump, the inlet is the one going to the center of the head and the outlet is the one going out radially from the pump head. On the riptide the outlet is the one with the built-in valve.

What I meant is that I rotated the head to change where the inlet/outlet side was. I didn't change the connections. But you raise a great point about which side is inlet. I thought the valve was on the inlet side! Could this be why I'm having so much cavitation?

 

[Bago-0]

I did this the first time I used the Riptide. Just hooked it up and didnt think about input and output sides. The ports on the pump are marked , In and Out.

 

[Vale71]

If you connect the wrong side you don't get cavitation, you get the pump pushing in the opposite direction than expected. This will simply push the water/wort back into the kettle until the pump head empties and stalls causing it to pulse.

 

[ImperialDrHops]

I did this the first time I used the Riptide. Just hooked it up and didnt think about input and output sides. The ports on the pump are marked , In and Out.

I finally had a chance to test out the pump hooking it up correctly and low and behold, it works absolutely fine. Looking closer at the pump there are no labels defining in and out except for a very small arrow on the pump head pointing in the direction of flow. But it's so small and not labeled that someone like me with inexperience missed it. Blichman should really put this in the instructions. But I'm happy people here were able to help because Blichman support didn't even catch this. Thanks everyone!

 

[user 298779]

Blichmann has since tooled “in” and “out” on pump head along with arrows. Your issue was cavitation, but I won’t waste space here writing about fluid mechanics & hydraulics.

Glad it‘s working for you now. If your pump gets noisy again and you know it’s not a suction or cavitation issue then turn it off, disassemble the head, and lube the o-ring and reassemble ensuring it’s now sealed correctly.

Cheers

 

[oakbarn]

We have always filled our vessels (Strike Water to the MLT and Priming Water to the BK) backwards through the Pump (with the pump off) to get rid of any air. We used to have lots of cavitation issues but that seems to have taken that out of a brew day.

 

[user 298779]

Oakbarn that’s a great method to ensure pumps are primed! Never heard that but I’ll be trying it in the future.

Cheers!

 

[Bobby_M]

This is all just new pump owner learning curve at work. When the pump is loud and doesn't pump, you have air in the head trapped there by liquid in the lines on the inlet and outlet. While the vent is not needed to get the pump primed, that's precisely why Blichmann put a vent into the head. With the pump off, pull the ring until the outflowing air is replaced with some liquid.

More practically, you will learn how to first flood the inlet hose, then connect it to the pump.