Air coming out of Mashtun during Vorlauf

[Chris Levesque]

I recently was given a sparge arm and started using it. My last 3 batches I've used it on I've noticed a fair amount of air coming out the output of my mashtun.

I checked and I don't have a ball valve with an air hole in it and I'm using camlocks to secure my hoses.

When I first turn the pump on it flows like a dream and then the air slowly builds up and reduces it's flow, eventually to a full stop. I then have to turn the pump off and then back on after a few seconds to get that flow back again.

I have a RipTide pump, so I know it's not for a lack of power.

Any other ideas?

 

[tll77]

Is the outlet of the sparge arm above the liquor level in your mash tun?
Is the silicone washer in your camlock compromised somehow?
What sort of false bottom or manifold or such are you using?

 

[day_trippr]

Sure sounds like the mash bed is seizing up, which shouldn't have anything to do with that wort aeration device...

Cheers!

 

[Vale71]

You can't get air from the bed seizing up (the flow just stops) or from the sparge arm (any air will just float to the surface).
The most likely culprit is air trapped under a false bottom that eventually gets pulled out by the pump.

 

[GilaMinumBeer]

Cavitation maybe?

 

[Vale71]

Cavitation happens inside the pump and is a dynamic process, with the vacuum bubbles surviving for a few milliseconds. If that were vacuum and not air the hose would collapse completely.

 

[Bilsch]

Could it be low flow through the mash that is increasing the suction and finding air leaks somewhere in the inlet plumbing or pump seals? Can you pressure test your recirc circuit?

 

[Chris Levesque]

I currently am using a Bayou Classic with a false bottom. I heat up the strike water in the vessel (with false bottom in place), then add grains to it. No way there'd be "trapped" air under the false bottom. I think I'm going to check the silicone seals and just try running it with water to see if it repeats.

 

[Smellyglove]

Before I dialed in my recirculation flow (do you recirculate?) I'd get air trapped under the grainbed. It would usually rise to the top when I stopped the pump to reorientate the hoses for draining to BK. Maybe the same is happening to you, but the air doesn't float up, but can only get out through the hose?

How does the grainbed feel like? Is it hard on the bottom? It should be like stirring a pasta all the way down.

 

[day_trippr]

You can't get air from the bed seizing up (the flow just stops) or from the sparge arm (any air will just float to the surface). [...]

I didn't say the air was coming from inside the tun...

Cheers!