Almost a catastrophic brew day...someone help me understand what went wrong?

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bassicrob

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Some time ago while I'll was still brewing outdoors, I had an event that I still don't quite understand how it happened and spooks me every time I brew, even more so that I've moved indoors. My setup is as follows:
  • Robobrew
  • Bottom port to Blichman pump
  • Pump outlet to inlet of Chiller Plate
  • Chiller Plate Outlet to Homebrew Hardware Recirc arm back into Robobrew
  • All hoses are brew-rated silicone
Below is my setup during sparge. Recirc arm not connected yet
20190518_161219.jpg


I was recirculating near the end of the boil, roughly 45min into a 60min boil. Pump was primed and open, bottom port valve of Robobrew was open, and wort was moving. I might've made a minor adjustment to the outflow control on the pump and suddenly the hose between the Robobrew and pump started to swell up like a balloon. I closed the Robobrew bottom port valve, scaled the flow valve to zero on the pump, and disconnected (thank goodness for QDs!) the hose before it burst.

Since then (15-20 brews later) I've not had any issues but I still don't fully understand what happened, other than somehow the liquid must have super heated within that first hose but I still don't understand how. Can someone help understand my process and what I might have done wrong? I'd like to not attempt it again and be more mindful, especially with hot wort and now brewing indoors!!
 

IslandLizard

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[EDITs] Are these thick-walled (1/8" wall thickness) 1/2" (ID) silicone hoses, not thin-walled ones?

Unless there's pressure built-up inside the (thick-walled silicone) hose, due to some restriction, I cannot see it starting to bulge just by transporting hot liquid.

Was the plate chiller in line while recirculating? Maybe that plugged up due to hops going in there.

Doesn't the Robobrew have it's own recirc pump in the bottom? That could cause pressure built-up in the hose going to the Blichmann pump.
 
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Deadalus

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If you do have hops in the system, is there a screen of some kind before exiting?

You have a low drop and the Blichmann is a good pump. You aren't losing much pressure to gravity. Your hoses you say are brewrated silicon, but they could be thinner than others. Even if not, I have good tubing but it still flops over at times if hung non-optimally. I have two March pumps and that will just stop the flow mostly and sometimes make them squeal. I don't lean this way as a cause though. I would say you have too much hose going from the pump to the plate chiller. Which I wonder, is there a correct orientation for your plate chiller and did you have it that way? My plate chiller grabs little bits of stuff that I CIP later and get out. Do you do something to really rinse out your plate chiller? I run PBW through the system for 30+ minutes and while doing that it goes through a hop spider which I see collects those little bits that were previously collected by the plate chiller.

What might have happened is a bit of something got closed into your exit valve. I have no idea though whether that can transfer pressure backwards through the impellor. When I close my whirlpool valve during sparging, this valve is after the outlet on the pump, I close it down real tight. Sometimes a little bit gets caught in the valve to where the flow is barely a trickle. The slightest nudge on the valve and sometimes that bit pops loose and the flow jumps. Reverse that thought and maybe you had a clog.

Just some thoughts.

Oh and potentially a defect in the hose.
 
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bassicrob

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The swelling was on the inlet hose to the pump? Whereabouts? Was the wort hopped and if so what kind of hops, leaf or pellet?
Yes the entire hose swelled like a balloon before I closed the valves and removed the QD. Hot wort was clearly pressurized as it shot out from the disconnected end. Wort was hopped but they all go in a hop spider.

[EDITs] Are these thick-walled (1/8" wall thickness) 1/2" (ID) silicone hoses, not thin-walled ones?
Thick walled, yes. Got from either More Beer or Homebrew Hardware.

Was the plate chiller in line while recirculating? Maybe that plugged up due to hops going in there.
Plate chiller was inline. It's a possibilty, but I always flush the chiller before and after brew day in both directions. This assumes some matter bypassed the hop spider.
Doesn't the Robobrew have it's own recirc pump in the bottom? That could cause pressure built-up in the hose going to the Blichmann pump.
It does but I don't use it. I don't get a whirlpool from it and I don't get good flow out of it. Worthless if I had to do it again.
 

Deadalus

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My mash tun lets through little bits, it has small round holes. I tried a t-handle screen underneath but it would clog, not enough surface area. I recently got a smaller slightly domed false bottom, an old Phil's product, that I added under the main false bottom. (I think a slotted one would work better). Anyway, I still get some bits in the plate chiller after flushing so I include it in my CIP procedure. My hop spider is I think 400 microns and it still catches some material. And I flush mine three times both ways for 30-60 seconds before CIP. Some of it is irish moss too, I don't feel that would be effective in the hop spider.

How open was your outlet valve when you slightly adjusted it? You were turning it down? If it was full open, I wouldn't guess anything normal would have plugged it. Whole hops maybe. It wasn't anything before the pump as the hose would have collapsed. Check the outflow valve to be sure it opens and closes properly. You could disassemble the pump and make sure nothing is built up in there. And maybe a good PBW recirculation through the whole system, and I recommend getting a screen somewhere in the loop to see what might be getting knocked loose while you do it.

When I am about to shut off a pump, I generally close a valve in the loop on the out side, then quick cut the power then close a valve on the in side to keep primed. This avoids collapsing the tube. I have also extremely restricted the out valve during sparging. I've never had my tubing bulge though. I have roughly a foot drop from my table down to a shelf where my March pumps sit. I'm pretty sure the Riptide is a little more powerful but not particularly greater.

And is there some way to be sure that recirc pump wasn't working? You probably can hear it I'd guess. Just trying to be thorough because I totally understand not wanting hot wort all over the place!
 
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