Issues with Flow Rate and Entrained Air

meadowstream · Joined: 02 Jan 2011 Posts: 16

Somehow, air is entraining in my system and slowing flow rate to near zero. I turn off the pump, prime it, check the head...all with no effect.

Any ideas?

**kal** · Posted: Sat Aug 05, 2017 4:43 pm Post subject:

If air's getting in somewhere you'll have to look at all points in the loop and check for leaks. I've heard in the past where some people had poorly made or defective quick disconnects that leaked this way.

Kal

McGruber · Joined: 12 Aug 2014 Posts: 237 Location: Idaho

I assume you're talking about this problem in your MLT. You're getting low to no flow and noticing air in the line from the MLT to the pump. I'd be willing to bet that you'll notice that your sight gauge is also dropping to (or very near) the bottom of the glass.

I've had this problem too and thought that there was an air leak somewhere also. Keep looking for the threads on this forum, there are several, and look up "Cavitation" (cavitation has more to do with those bubbles exploding in and damaging pumps - but the bubble formation is the important part). What is more likely happening is that your mash is getting stuck, the pump continues to pull negative pressure on the fluid and air in the wort is expanding into visible air. You're getting low to no flow because your mash is jammed up, not because of the air. That air can cause you to lose prime, but the air is the symptom of a stuck mash, not the main problem.

I'd suggest you mill with a wider gap and/or try rice hulls if you're making something with oats or wheat. When it happens again, shut off the pump and stir the mash, let it settle for 5 or 10 minutes, turn the pump back on and SLOWLY open the discharge valve. I open mine over two or three minutes. Watch the sight glass once the valve is fully open. If it's dropping to the bottom, your mash is stuck and you're going to see air in the line and will need to re-stir.

**kal** · Posted: Tue Aug 08, 2017 7:07 pm Post subject:

Good points by McGruber.

What mill gap spacing are you using?
What equipment? (Kettles, false bottom, pumps)
Has this happened with all beers?

Kal

meadowstream · Joined: 02 Jan 2011 Posts: 16

Thanks to all replies. I may actually have a problem as Kal suggested: there are some scratches on the mash tun outlet that came from my handling it poorly while cleaning once.

And it is possible that I am milling too finely, too. My mill is set for 0.043 and maybe I should increase to 0.045?

Haven't used rice hulls before - how do you add them and how much (what ratio?)

Thanks again!

**kal** · Posted: Sat Aug 19, 2017 7:13 pm Post subject: