Needle valve on reflux condenser??

[Steelers_Stiller]

The question is: Should I install a needle valve on my reflux condenser?

1/4: O.D. copper reflux condenser. Double helix. 10" of coils, not counting tails. The condenser will be on top of a 2" column.

My coolant hoses are going to be 3/8 ID poly tubing. I have 1/4 turn shutoff connectors that will be installed at the 1/4 copper to 3/8 poly junction. They could be used to adjust flow, but have no fine tuning capability.

Do i need the fine tuning abilities of a needle valve or will it be too restrictive?

I already have 2 needle valves and 1/4 turn shuto9f valves so the cost is irrelevant.

What setup is best?

[Steve Broady]

I’ve been using a cheap garden hose shutoff valve to control water flow to my leibig, and it’s worked well enough…

Until I added a dephleg in series with it to help bump proof a little in a stripping run. Set up like that, outlet temperature is pretty important and I found that it was just about impossible to get that 1/4 turn ball valve adjusted properly. I finally added a vise grip to the handle just to get a little more leverage.

You didn’t say what kind of still you’re going to be running, but I’m going to say that if it’s anything that needs any kind of reliable tuning of the water flow, use a needle valve or a flow meter. That 1/4 turn valve will likely be a headache. Especially since you already have the valve, I say use it.

[Bushman]

With the two reflux stills I have built I only used a ball valve that for me worked fine. The still that was given to me has a needle valve but i am yet to run it for a comparison.

[higgins]

I'd say 'it depends', but if you already have one I'd go ahead and use it.

If you are running the RC at the top of a VM, CCVM, or LM column I'd say you don't need really fine flow control, so almost any valve should work OK.
If you are running the RC as a dephleg on a CM still, I'd say yes because you do need fine flow control.

I made mine so that it can be use as either RC or dephleg. I put mine inside of a 6" section of 2" copper tube with SS ferrules on each end. When using it on a CM as a dephleg it projects down into the top plate section to minimize the height that it takes up. When using at the top as a reflux condenser on my VM column I add a 2" x 4" spool and the RC above my takeoff tee.

In CM mode I need to run about 750 ml/min thru it for 100% reflux, dropping down to around 350 ml/min during the hearts portion of the run. The needle valve was very finicky to get just right. I found a flow meter that was adjustable from 0-1000 ml/min, and it worked very well.

This works really great - much easier that fiddling/farting around with a needle valve. Even without a constant supply pressure (as with a water tank/recirc pump) it is pretty easy to react to pressure changes on my house water system.

[Saltbush Bill]

If it's a true reflux condenser sitting on top of a packed column then there is no need.
If on the other hand it's purpose is to act as a deflegmator on a plated column then yes it is a good idea to use a needle valve.

[OtisT]

It’s not necessary for a RC over a packed column, but if you have an option I would choose the needle valve.

The needle valves I have used are not restrictive in any way as they have plenty of flow potential. My adjustment range is between 0 and 1/2 turn (0 to ~3 liters/minute which is 5500 W of cooling.). A full turn open is 6 liters/minute which is more than I have ever needed for my 5500 W system.

I don’t recycle water and try to conserve every bit I can. The needle valve makes the fine adjustments I want to make easier and less frustrating to hit my target flow.

[Steelers_Stiller]

Great posts, thanks all.

The condenser is going on top of a 2" VM column so it sounds like it won't really be needed but since I have it, might as well put it in.

[Salt Must Flow]

Great posts, thanks all.

The condenser is going on top of a 2" VM column so it sounds like it won't really be needed but since I have it, might as well put it in.

Test it with hose/tubing and see if it works well. As long as you have precise control over the flow, it will work. I use needle valves on all of my condensers, but seeing is believing.

[Steelers_Stiller]

I scavenged some copper pieces off an old 200A fuse and soldered them onto the side of a piece of 2" copper pipe.
Soldered a S.S triclamp ferrule in the tube and inserted the reflux condenser
Soldered up some 90 degree elbows onto the condenser and soldered some straight pieces thru the "ears" on the pipe.
Put some compression style needle valves in both lines so the condenser can be removed with a wrench instead of a torch.
Did a pressure test on the new setup.
BOTH needle valves leak at the compression nut.
NEITHER needle valve will fully shut off the flow of water and neither seem to do much to alter the flow of water.

Not sure if I bought a couple of flukes or what. They came from Home Depot. I debated on exchanging them but decided not to bother with another junk valve from there.

Went to the local plumbing supply house that is professional sales only. I have an account thru work. They did not have an inline needle valve, only piercing/saddle valves.

Leaving the plumbing store, I passed a hydraulic repair shop. Gave them a ring. Asked if they had any 1/4" needle valves. They said yes, we have 2. They are nice looking, stainless valves. Around $17 each, not bad! Will swap them out later.

Here are a couple pictures with the non functional Home Depot needle valves. I thought it was looking pretty nice. Too bad it doesn't work.

[Tammuz]

You only need one valve to control the flow. I noticed most vm I remember have a bit more coil hanging down to be closer to the tee.

[Steelers_Stiller]

You only need one valve to control the flow. I noticed most vm I remember have a bit more coil hanging down to be closer to the tee.

The 2nd valve is there basically just to make coil removal easier. Plus, I've seen some argument over putting the valve on the output, vs input side.

I recently read here that the reflux coil should be about 1x the column diameter about the takeoff arm. The reflux coil is sitting up about .5 inches from the bottom of the this tube. I'm using a 2" Tee for the takeoff arm. Its 1.5 Inches from top of takeoff arm to top of ferrule soldered to tee. So, about 2" total.

[Salt Must Flow]

Ace Hardware should have them in stock for $12.99 each. That's where I've always bought mine and they have always functioned properly.

[Tammuz]

You only need one valve to control the flow. I noticed most vm I remember have a bit more coil hanging down to be closer to the tee.

The 2nd valve is there basically just to make coil removal easier. Plus, I've seen some argument over putting the valve on the output, vs input side.

I recently read here that the reflux coil should be about 1x the column diameter about the takeoff arm. The reflux coil is sitting up about .5 inches from the bottom of the this tube. I'm using a 2" Tee for the takeoff arm. Its 1.5 Inches from top of takeoff arm to top of ferrule soldered to tee. So, about 2" total.

I was assuming it stopped where your support bars for your waterlines are.

[Steelers_Stiller]

Installed some different valves and it's working good now!