DIY Removable Dip Tube

[benfarhner]

I'm in the thick of building my eHERMS based on Kal's design with a few changes. I'm using Concord kettles instead of Blichmanns, and right now I'm working out the dip tubes so I can determine where to punch the holes for the outlet valves.

I'm planning on using some segments from the 1/2" OD stainless steel tubing that's for the heat exchange coil as the dip tubes, and fitting them into stainless compression fittings with silicone gaskets instead of ferrules, so they can be removed and reinstalled easily. In my research I haven't found anyone else doing this, so I'm curious to see some examples if someone has, although I have no doubts it'll work.

My main question is: how tight of a bend can I easily make in the 1/2" OD tubing? That's kind of the deciding factor on how low I can install the valves. I've looked at tube benders, but they all seem to be in the 1-1/2" radius range, and I'm hoping to get a tighter corner than that. The Blichmann dip tubes appear to have fairly tight corners as well. Any practical ideas or examples?

I'll post pictures as I build this out so others have a reference in case they want to go the DIY route

 

[day_trippr]

Brewhardware.com has been putting compliant o-rings in compresion fittings for a couple of years at least. You might be able to get some ideas from the dip tubes on that site....

Cheers!

 

[benfarhner]

Actually, I got the idea from Bargain Fittings. I got my sight glass kits from them, and they use o-rings in compression fittings with the plastic sight glasses.

Doing some more research, it looks like the most practical radius for bending 1/2" OD SS tubing is going to be around the 1-1/2" mark, unless I use a mandrel and/or other tube bending tools. Looks like I'll probably make do with that, and just measure everything very carefully to get it as compact as possible.

I'm planning on ordering a false bottom from NorCal Brewing Solutions, and need to specify where the hole for the dip tube should be (if I need a hole), as well as the height of the stand for the false bottom.

I'm looking at 2 options right now:

1. Install the outlet valve at 1-9/16" from the bottom of the kettle, and get a false bottom with a 2-1/4" stand to fit over the top of the fitting (lower valve, easier to remove, but more expensive)
2. Install the outlet valve at 2-13/16" from the bottom of the kettle, and get a false bottom with a 1-1/4" stand and a hole for the dip tube to fit underneath the fitting (higher valve, more hassle to remove, but cheaper)

Those numbers assume a 1-1/2" bend radius through the center of the tube.

Anyone have experience with either or both of those options and what they like and dislike about each? I think it would be nice for the false bottom of fit over the dip tube instead of the dip tube running through it, but would there be any concern about the greater volume under the false bottom on a HERMS?

Thanks in advance!

 

[benfarhner]

My 1/2" OD stainless tubing arrived yesterday, so I can do some test fits and get more precise measurements soon.

I had another idea to get the ball valve lower, which would involve cutting off the tube before the bend is complete, leaving me with an oval opening. This would allow me to get a lower stand on the false bottom, and thus less liquid under the mash.

Additionally, I've noticed that the Concord pots I have bend slightly inward in the bottom 1.5 inches or so, i.e. they're not perfectly straight all the way to bottom. That inward bend will make my ball valve angle slightly downward if I mount it low enough, so that's another factor I need to consider.

My biggest concern with having the outlet valve above the false bottom and feeding the dip tube through it is that there won't be enough margin to actually remove the dip tube and false bottom. The Blichmann false bottom has an oblong opening to accommodate removal of the dip tube and what appears to simply be a washer to cover the gap. This would be a fairly simple solution if that's really all there is to it. Can anyone with a Blichmann confirm this?

 

[benfarhner]

Just wanted to follow up and post my results. I'm a bit surprised that I couldn't find anyone else making dip tubes like this, though I'm sure others have.

I purchased a 1/2" OD tube bender from Amazon that has a 1-1/2" bend radius, and used sections of the 50' heat exchange coil for the tubing.

First I did some careful measurements to determine the length of tubing I needed for each dip tube, then cut those sections with a tube cutter.



I then sealed off one of the tube with duct tape (I first tried rubber caps, but they didn't hold as well) and, using a funnel, filled the tube with sand.





Then I sealed the other end.



I made sure in my measurements that there was enough tubing on one end of the bend for the tube bender to hold, otherwise this would've been near impossible. Unfortunately I didn't take any pictures of the bending, since my hands were full, but it's straightforward enough. I just went very slowly and carefully. After bending, I peeled the duct tape off and poured out the sand.



As I said before, these were inspired by the Bargain Fittings sight glass kits. Here's the full assembly. I used the tube bender very gently to round out the straight sections as needed to get the compression fittings on.



The boil kettle dip tube is longer, to accommodate a hop screen (another easy DIY project). I followed the same procedure, but since I used tubing from a coil, I also had to straighten out the rest of the tube (this turned out to be a non issue on the shorter dip tubes).





They aren't the prettiest dip tubes, but I'm pretty happy with how they turned out. They're functional, my design worked, and it's a pretty easy DIY project. Since I already had the stainless steel coil for the heat exchanger, this turned out to be cheaper than buying prefab dip tubes.

 

[Gavin C]

Great write up. Great pics. Thanks for sharing your methods

 

[acidrain]

Biggest problem with this type of tube system is any tiny air leak will give you problems (break the siphon). If the o-rings seal good, great! If they don't, using the compression ferule doesn't mean you can't get it apart... it just means that the ferule and compression nut are on the tube forever. The nut can still be unscrewed, and the tube removed from the bulkhead for cleaning.