Cheap Needle Valve Modification

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Master Distiller
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Cheap Needle Valve Modification

Post by rad14701 » Wed May 13, 2009 12:54 pm

We all know how cheaply most inexpensive brass needle valves are made... Well, while searching around for a better valve that didn't cost a fortune, at least by my monetary standards, I decided to see if I could "fix" my cheap needle vale instead...

Doubting that I'd be able to make any improvements on the existing needle valve assembly I decided to tear it apart, just in case... What I found was that the "needle" didn't come to a point and that it was actually bored hollow at the business end... This got me to thinking... I figured, piss on it, the least I can do is to totally wreck the thing anyway, so I tore it apart to see what I could do... I removed the handle (pin) from the needle and then slid the rubber (Grrr!!!) O-Ring off the needle...

Now all I was left with was the brass needle with the hole in the end... I grabbed my 40W soldering pencil, flux, and lead free solder, and proceeded to fill the hollow "point", as well as forming a glob where the actual point should have been... I got it pretty accurate on the first shot... Yeah, sometimes we get lucky... Only got a very slight amount on the threads, but not enough to worry about yet just enough to help improve how snug things fit together... Again, sometimes you just get lucky...

Next, I took the newly modified needle and screwed it back into the body of the valve assembly... I had slid the handle (pin) back in only slightly so I had some leverage... I screwed the needle back down into the body, backing it off after every quarter turn or so, until it bottomed out... Then I removed the needle to see what I had... I was surprised...!!! The solder had managed to conform to the exact shape of the bottom of the valve with very little effort at all... Yep, again, sometimes you just get lucky... Too good to be true was what came to mind... Or was it...

So, being as I was doing this because I wanted to run some older neutral spirits that I'd run off while experimenting and also wanted to toss in my accumulation of heads and tails, all that remained was some testing... I cleaned the valve up and put it back onto my small scale rig to give it a workout... I charged up my 8 liter boiler with about 1.75 liters of not quite neutral spirits, heads, and tails, topped the boiler to about 6 liters with water, and fired things up... Suddenly I realized that this might not work, but there was no turning back now...

As the temperature rose in the column I wondered if I would have better control over my take off rate or worse... Once the column temperature rose to 172F, and sat at 100% refluxed for about 15 minutes, I was ready to see how well the modified needle valve worked... Surprise of surprises, the valve worked great...!!! The adjustments that used to happen in about a quarter of a turn on it originally now took several turns... Seriously, what used to go from no output to pissing a stream used to happen in about a quarter to a half a turn... Now I had about a quarter to a half turn or more per drip for adjustment control... Eureka...!!!

So, overall, it was an unexpected success... I was able to control the entire run, holding the column temperature at just about any temperature I desired... As the run progressed and the ethanol in the wash was reduced, I was able to make adjustments... I ended up with 1.25 liters at 90%, overall, by making proper adjustments to the modified needle valve... I could have held the output at 95% but time and experimentation made for a 90% average - not too shabby... As the temp started to climb I was able to adjust back into my target range and then shut down as soon as I was chasing a runaway train... I pulled every bit of almost pure ethanol out of what I started with and never even touched the tails region before shutting down... I could very well have done the happy dance, but I refrained...

So, while I was drooling over $12, $22, $50, $80 needle valves that I had found on the internet, I managed to achieve adequately comparable results for $0... And I didn't even have to break out a file, much to my surprise... I'm happy as hell and feel downright lucky that I was able to make the modification in a matter of minutes and without a lot of modifications... I can now push that 22-24 turn precision needle valve further down on my wish list...

Sorry... Only occurred to me now that I should have taken a few pictures... Hopefully, my explanation will suffice if anyone decides to try this... Oh, and I forgot to mention that I did re-pickle the needle between modification and actual use... Can't be too safe even though we've been told that these valve "may not" have lead in them...

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Re: Cheap Needle Valve Modification

Post by Buckeye » Thu Jun 04, 2009 1:30 am

I'll have to dissasemble my needle valve and see if I can do this mod. With my luck I'll need a file.
Electric keg, 3500w (2 element 110v), 20A variac controller, 2" Bok with 45"copper packed column.

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Re: Cheap Needle Valve Modification

Post by Ayay » Thu Jun 04, 2009 2:48 am

Like you Rad I pull stuff apart and modify where necessary. I have a number of 'needle valves' from the recycling center that turn out to be no more than on/off loss at $1 each.

If only the sales rep could pull the valve apart on the counter or provide a detailed bluprint before selling. Not likely when a few glib words makes a sale, but when it happens there is a premium to pay.
cornflakes...stripped and refluxed

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