Making the dreaded T500 safe

[jpsobral]

First of all this looks a beauty still at the end of 2022 - very well made Andy!

Can you share your CAD file with us? I would love to have a custom-made piece like yours!

All the best and happy new year

Hi People

sorry its been a while been busy with stuff.

i have got the machined part from work and the PTFE o-ring replacements and put it on my still, can't say ive noticed a difference but at least the still is "safe"

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let me know what you think

Andy

[hawkwing]

Does the lid have a silicone seal and what did you do to make it safe?

[tomlain]

Hello fellow distillers,
I’ve been distilling for a couple of years now, so still reasonably new to it. I got into it because I wanted to make Limoncello and needed high ABV spirits to draw the limonoids out of the lemon peel. Started off with a Chinese ‘football’ still, then bought a second hand T500. I’ve done around 20 runs with the T500 and have been enjoying it. It creates a great, clean spirit, with very little tails. But, like many others, I have 3 issues:
1. The plastic cap, (I definitely agree with rule 1.i of the Home Distiller board rules “no plastic in the run line”.
2. The lack of a temperature probe in the still column head.
3. Separate water flows for the condenser and reflux columns.
I could include of fourth issue that others have mentioned, that of the column needing to be longer. However, I believe it is always a good idea to ask yourself, "Just because I can, does that mean I should?" I have to admit, I didn’t know the answer to that, so I asked someone who did. I spoke with my local brew shop owner about extending column height. He has used the T500 extensively, and for many years. The only extension he has done is to add a sight glass so he can see what is going on. It makes negligible difference to the finished product. After speaking with him I decided not add any extension on the T500 column. Further reasons being:
• The column height to width ratio is about 1:12, which is less than the ideal 1:15. But the column is married/tuned to the boiler. So, if I changed one, I would probably have to change the other.
• The T500 already produces a high-purity distillate at a very efficient operating cost. The expense of adding a sight glass or a 50cm/19” copper extension and all the fittings ($225AU in 2024), for a negligible improvement in purity doesn’t seem worth it.
My conclusion is that you would be better off buying a different type of still. But, good luck to anybody that wants to try it. Let me know how you go!
I’ve researched other people’s suggestions, experimented with them and come up with three cheap modifications. They require a reasonable amount of workshop knowhow, metalworking skills and tools. Get some help from someone who has these skills if you are unsure. Now some words of warning.
WARNING WARNING WARNING
For those of you who have only recently purchased a T500, before you do any modifications, use it a few times as it is. Get used to it, even if it’s only doing a few water distillation runs.
I recommend this because the first modification BYPASSES THE STILL SPIRITS PRESSURE RELEASE SAFETY FEATURE which allows not only pressure release to stop EXPLOSION, but prevents a vacuum IMPLOSION. So, it is safer if you are familiar with the T500 in its unaltered state before you go modifying it.
If you do decide to modify it, do it knowing that IT IS AT YOUR OWN RISK, AND THAT I ACCEPT NO RESPONSIBILITY FOR ANYTHING THAT MAY GO WRONG, OR ANY INJURIES YOU MIGHT INCUR.
Having said that, I see no real reason for this still to implode or explode if you take the two simple precautions:
1. Drill a hole in the new copper cap column head and put in a thermometer or a piece of cork, and
2. As SOON AS YOU HAVE FINISHED THE RUN AND TURNED THE POWER OFF, carefully/safely, with gloves/eye protection, flip the lid clips, OPEN THE LID and pop something in there (like a screwdriver) to keep it open.
Simple. These safety issues will be discussed in a bit more detail towards the end. But if you are at all unsure what you are doing, speak with a plumber, electrician, or engineer before going forward.
The best part of all three modifications is that you will be able to put your T500 back together again just as it was.
As I am Australian, I have used metric units, with freedom units listed after. I am unfamiliar with freedom units, please do your own conversions if mine seem a bit odd (like I don’t know if there is a such a thing as a 16/64” drill bit!).
The first modification is replacing the plastic cap with a copper one. You will need:
• A 50mm (2”) copper end cap,
• 10cm (4”) of standard, 12.7mm (1/2”) copper tubing,
• Lead free (Aquasafe) solder
• A brazing torch (or the wife’s kitchen culinary torch)
• Teflon PTFE plumbers’ tape
• Stainless steel hose clamps.
• Some O-rings, or the rubber washer from water tap washer (or you can use more PTFE tape if you like).
You will also need a reasonably well stocked workshop.
The 50mm (2”) copper end cap should look like this one:

Make sure with the supplier that the INTERNAL DIAMETER (ID) of the cap is 50mm (actually 50.8mm/2”). The T500 column has an EXTERNAL DIAMETER (ED) of 50.8mm/2”. This cap will fit loosely over the top of the column. A hose clamp and the rubber O-ring inside the cap will seal it.
When you have your parts, take your column apart. Remove the column from the lid. Remove all the packing. Undo and remove the short hose at the top of the column. Remove the press nut/washer at the top of the column by prying it up with a fine screwdriver until you get enough space to grab it with a pair of pliers, then twist and pull it up the pipe. You will probably crush the press nut, but don’t worry, you won’t need it (or you can flatten it out again, or buy a new one).
Undo the 2 top screws, and the 2 bottom screws with whatever you can find to fit them (if you are trying to find the right head for these screws, they are called Robertson screws, also known as a square screw or Scrulox).
Put little smear of Vaseline on the end of the copper pipe that comes out through the plastic cap. Firmly pull up, rock, and twist the black plastic cap until it slides off. Wipe off the Vaseline. Take this opportunity to have a look at the inside of the column and the cap, see how it all fits together and works. Have a smell of your column. Perhaps it’s time to give it a good wash out! I used a long bottle brush, brushing from both ends. Then soak the copper and stainless steel saddles and the column overnight in a weak 1/20 vinegar solution. Give it another brush out the next day. You probably won’t get all the smells out, but it will be better.
Make the End Cap Connector Pipe
Now you have the column apart it’s time to shape the end cap connector pipe. This small pipe will join the reflux column to the condenser pipe. Take your 10cm (4”) of 12.7mm (½”) diameter copper pipe and slide it over the condenser pipe. You’ll notice that it is too large in its internal diameter, by about 1mm (3/64”). Not to worry! You are now going to work on your blacksmith skills. Mark out the last 3cm (1 3/16”) of the 10cm/4” pipe. Wearing gloves and using a pair of needle nosed pliers to hold one end, heat the other end with a gas torch. It doesn’t have to be red hot. Use the pliers to hold it on a piece steel or other hard surface. Then, using a small hammer start tapping on that 3cm (1 3/16”) end, tap it a bit, roll it bit, then tap again. Tap tap tap, roll, tap tap tap, roll. Keep working, tapping and heating it every minute or two. The aim is to reduce the diameter so it is a snug fit over the horizontal column arm pipe. Keep going until you are happy with it. If you’re not happy, cut it off and start with a new piece! It doesn’t need to be tight, just snug, it will be hold in place with a steel hose clamp, so it should slide on and off easily. You should end up with something that looks like this:

Take this opportunity to polish the beaten end up using a wire brush or sandpaper. It’s easier to hold on to and polish before you cut the end off. This beaten end piece of pipe is then cut to the correct length to fit between the inside of the press end cap, over the horizontal column arm pipe and up to the condenser pipe. I cut my piece off at 21mm (53/64”), but like all these measurements, they are for my T500. Please make your own measurements, make sure they fit your still:

Soldering the Connector Pipe to the End Cap
Now to work on the 50mm copper end cap. Remove the black rubber O-ring from the inside of the end cap. Now take a thin piece of wire or a paperclip and make an ‘L’ shape with it, long side about 5cm (2”), short side exactly 6mm (15/64”), like the one in this picture:

Use this piece of wire to find the point where you will drill a hole for reflux cooling pipe to come out. Hole punch at the very tip of the ‘L’, then drill a 6.5mm (16/64”) hole.

To be continued...

[tomlain]

Next, drill another hole in the end cap for the small connecter pipe you’ve made to fit through. I came down 9mm (23/64”) from the top of the end cap, punched a hole, then drilled it out to a size that suited my pipe. Because you have beaten your piece of pipe to your own individual size, you will need to match your drill size to it. I used a 10mm (25/64“) drill, then filed it out with file drill until it was the right size. Remember, it is easier to make a small hole bigger than a big hole smaller!

You are now ready to solder it together. Make sure all your pieces of copper are clean and shiny. Put flux on them. Remover any pieces of plastic, rubber O-rings (anything that will burn) from the end cap and condenser tube. I found it was easier to get the column assembled together, nice and straight, fix it in place with a cable tie or piece of wire in a vice, then solder in situ like this:

Put on thick gloves for this. Solder in (with lead free solder) your measured and beaten piece of pipe. Heat the copper around the join, then apply the solder to the join. It should suck in nicely if the copper is hot enough - if you haven’t done much braizing and soldering of copper pipe before, have a practice on a few scrap bits first. You should now have it soldered in nice and straight.
Word of warning: Don’t use PTFE plumbers’ tape instead of solder for this join. This join provides stability between the reflux column and condenser tubes. Soldering is sturdier and safer.

Take your end cap off and cool it down with cold water. Then drill one last hole in the top center of the end cap. This hole with house the temperature probe or a small piece of core, and will end up being your safety release valve. I used a 5mm (13/64”) drill and put in a spare temperature probe I had:

To be continued...

[tomlain]

Put your O-ring back inside the end cap. Put a 53mm hose clamp on the column. Slip the end cap on and pull it down over the column. It will be firm because of the O-ring.
The reflux tube coming out the top of the end cap will need an O-ring, washer, or some PTFE tape to seal it. I had a red tap washer that fit nicely, so I used that.
You can either hook the inlet/outlet hoses and temperature probe up the way there were originally, or go on to the second modification, which is having two input and two output hoses. Whatever you decide, you MUST:
1. INSTALL A SAFETY PLUG IN THE TOP OF THE COLUMN. Either a temperature probe loosely fitted in the top of the column with a bit of PTFE tape, or a piece of cork shaped to fit the hole. This will allow any pressure to be released in the (unlikely) event that your distillation path gets blocked.
2. When you have finished distilling, as soon as you turn off the boiler, unclip and OPEN THE LID. Leave the water running through the still. Put on gloves and safety goggles, undo the clips and tilt the column and put a screwdriver between the lid and the boiler. The first run I forgot to do this. Within seconds of turning off the boiler I could hear gurgling. I thought it was condensate trying to get out. It wasn’t. It was in fact air being sucked back through the distillate hose (where the alcohol drips out) at a very fast rate! I put my finger over the end and there was a definite vacuum. I immediately unclipped the lid, tilted the column and put a screwdriver in there to keep it open. I don’t believe the still would have imploded. But I didn’t want to find out! Taking out the temperature probe at the top would have helped here also. Further notes of vacuum warning:
• Do not distil alcohol above 40% ABV as this could also cause a vacuum, and
• Do not submerge the distillate out tube in a liquid because air cannot flow into the boiler through the outlet tube. This will cause a vacuum and the boiler to implode.

I suggest at this point you test out your new copper column end cap by doing a 10L (3 gal) distilled water run without the column packing. Set the inlet and outlet hoses up as they originally were. The temp probe can stay in its usual place. Plug the top hole with a piece of cork. Look for leaks, be ready to apply hose clamps or mark and rework any join issues once it has cooled down.
First mod over and done with. Well done!

[tomlain]

Temperature Probe In The Still Column Head
Now onto the second modification - putting a temperature probe in the still column head. Let me say straight up, that this mod isn’t necessary, and I wouldn’t bother with it. The way the T500 is set up with the temp probe in the water outlet works just fine. Feel free to disagree with me here! But if you really want to do it, read on.
Another question you might be asking is: Do you need to buy another temperature probe? No, not unless you want to. You can move the outlet temp probe up to the column head, and plug the hole where it came from. I had another temp probe already, so I used it and now have two temp readings (both of which I largely ignore!).
Even if you’ve haven’t replaced the reflux column head with copper and you still have the original plastic one, you can still put a temp probe on top. I would advise removing the plastic (or copper cap) from the column when doing this mod. You don’t want pieces of plastic or copper falling into your packing.
Drill an appropriately sized hole in the center of the column head, 5mm (13/64”) should do it. Using plumbers’ tape, wrap the metal end of the probe and put it in the hole so that it sits there loosely. It doesn’t need to be tight as there is not much pressure in the column head, just heat and condensate flowing past on its way to the condensation column. The original T500’s had a screw in temperature probe, but I’d advise against using this. Remember, it is going to be the safety release valve if there is too much pressure build up in your column (especially if you’ve done the copper end cap modification).
As previously stated, if you don’t want to put a temp probe in the copper end cap, get a small piece of cork, shape it and plug the hole loosely.
Running the T500 with Two Temperature Probes and Inlet/Outlet Hoses
How do you now run the T500 with this new temp probe in the top of the column? You want the top temp probe to run at 78 deg C. Easy. Drip, drip, spurt.
For the bottom temp probe hole you have two options:
a) Plug it up with a piece of stainless steel or copper wrapped in PTFE, or
b) Leave the probe in there and have a second up top (more temps to look at).
I agree with many other distillers’ views on running the T500, temps aren’t that important, it’s spirit output flow that you want to watch, drip, drip, spurt, drip, drip, spurt. Start with a good, clear wash to begin with. Let it fully reflux in the column for 30min then start your stripping run. Do the same for your spirit run, then polish your diluted 45%ABV spirit with activated carbon. This will give you lovely, clean spirits.
If anyone wants to know how to clear a wash with bentonite, let me know and I’ll post how I do it.

Separate Water Input and Output
The third modification is a separate water flow for the condenser and reflux columns. Once again, it’s good to ask, “Just because I can, should I?” Well, initially I thought this would be a good idea. Why? I thought I would get finer control of your column head and reflux. That’s where the magic happens, and that’s where you want know what the temperature is. But it really is a PITA. It does take a little bit of getting used to operating the still, and I don’t think it’s worth doing. It’s cumbersome, finicky and unnecessary. Not to mention, with 4 hoses hanging out of it, it makes the still less appealing to look at.
But if you want to know, here’s how to do it. At the top of the column is the reflux column cooling water inlet. This is where you want the water to go IN and subsequently DOWN. Remember you always want the water to running in the opposite direction to the condensate which is going UP the column. Identify the column inlet, attach your hose to it, and you MUST put a micro flow controller in this line, like this one I bought on Aliexpress for a couple of dollars:

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Note: With these micro controllers, they only work with the water going in one direction. So, if it’s not working properly, turn it around!
You will have very fine control of your water flowing in now.
Next, attach another hose to the condenser column inlet, which is at the bottom of the smaller column. Once again, the water flow will be moving against the direction of the condensate. You will also have to put a water flow controller on this line (we’ll call it a macro controller). A garden hose valve like this one will do:

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Once you have both these hoses connected, you will need to join them together. For this you will need two Y connectors. The inlet hoses will need a Y connector, and your outlet hoses will also need one, like this one:

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How will it all fit together? The inlet water will come in from your water supply to the Y connector, where it will split. One hose going off to the micro controller and reflux column at the top, and the other going off to the macro controller and the condensation column at the bottom.
The condenser out and reflux out hoses will join up to the other Y connector, then your warm output water will head off in one hose outside, or wherever you would normally put it.
How to run this setup double hose, double temp probe T500 still?
Well, it will take a little getting used to, but if you are determined to do it, here’s some guidance.
Put your 25L of clear wash in the boiler. I put in a handful of marbles which give me a good indication when boiling is occurring, makes the boil even, and is supposed to stop puking. Close the lid, turn on the power to the boiler. After about 50mins the wash will start to ‘boil’ and condensate will be rising up the column. Turn on the needle valve and drop the temp in the column (read from the top temp probe). Reflux it 100% for 30min using your reflux needle valve. 100% reflux means no alcohol is coming out of the condenser outlet. After the 30min, turn on some water to the CONDENSER LINE with your macro controller. Remember, adjusting the macro water flow will affect the micro flow rate because they are coming from the same Y connector source. The flow rate from condenser should be sufficient that the spirit output is cool if you feel it with your fingers. Simply modify the flow by feeling the alcohol output until it is cool.
Slowly lower the water flow to the reflux column with the needle valve until you start getting spirit output (remember to keep it cool with the macro controller). Monitor the reflux column temp (read from the top), keeping it to 78 deg C. Collect your first 50mls of foreshots, discard or set aside. Then start collecting your heads, hearts and eventually, the inevitable tails.

That’s it. That’s the mods. As you can see now, the separate water inlets make it more difficult to run. I think the Still Spirits people have it right with their one inlet, one outlet system. It’s far simpler. But I still think I prefer the temp probe up top of the reflux column. Remember though, watching temp is all well and good, but the best indicator is spirit output flow is drip, drip, spurt.
Happy distilling!