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How cold a product condenser is cold enough?

Just wondering how to minimize water flow through the PC.

  1. Do you measure outflow temp? What's a good number there?
  2. Suggestion for a cheap flowmeter?
  3. How do you see when the PC gets too warm?

Till now I just let if flow and try with my hand if the PC feels cold, but that's not very water preserving...

I consider myself a newbie - Thank you for your patience!

Comments

  • Are you running from a tap or recirculating via a tank? lve never bothered to measure temp from pc because I use a tank. But some on here do either manually or with pid control, hopefully they will let you know.

    As long as it condenses all the vapor and output is cool enough for accurate abv reading that's all you need, and l reckon that's not a lot of water needed anyway.

    Fadge

  • Also you can get mechanical flow meters or electronic, but they need to in the low range say 0 to 2 Liters per min for our usage, max 5lt min.

    Fadge

  • edited March 2015

    Tap water, pretty cold (but can't tell how cold, haven't measured yet).

    Can you use a PID with outflow temp measurement after the PC with a thermotee? I don't want to have that condenser modified (and can't do myself).

    So what exactly happens when it gets to hot when using the SD surge breaker and parrot kit? I mean how can you see?

    Any specific recommendation for a cheap suitable flowmeter, that I can order online? Too bad that the SD team does not offer any.

    I consider myself a newbie - Thank you for your patience!

  • I use a one liter beaker and the stopwatch on my iPad.

    I'm more like I am now than I was before.

  • Run your hand against it. The top should be very warm and the bottom almost as cold as your cooling water, if the bottom is hot, increase the flow. If the top is cold decrease the flow.

  • Lately I've been thinking that for safety reasons, you should collect distillate at a temperature below the flash point for the concentration you are collecting at.

    Ranging from 29c/84f for 30% down to 17c/63f for azeotrope.

  • With our water temp out of the ground at about 82f, that 63f is laughable! Natural spring water here is 72f year round.

  • Reminds me of what the Sundance Kid said, "You jus keep thinkin' Butch, cause that's what yor good at."

    I'm more like I am now than I was before.

  • @FloridaCracker said: With our water temp out of the ground at about 82f, that 63f is laughable! Natural spring water here is 72f year round.

    +1

    Out of the tap during peak summer can be 90F. Never would have thought that till I seen my self.

    StillDragon North America - Your StillDragon® Distributor for North America

  • Oh come on, little chiller, litter recirc tank, no problem.

  • @Lovejoy said: Just wondering how to minimize water flow through the PC.

    1. Do you measure outflow temp? What's a good number there?
    2. Suggestion for a cheap flowmeter?
    3. How do you see when the PC gets too warm?

    Till now I just let if flow and try with my hand if the PC feels cold, but that's not very water preserving...

    been there, done that, got the t-shirt... Thermostatic Valve Installation on Product Condenser

  • I use 140F as my default temp on the outflow. I can measure that with my hand. If you can barely keep your hand in it...it's about 140F.

    I run my PC and RC in series...I keep the outflow from the Reflux Condenser at 140F...at 140F, if there is a small fluctuation in pressure I have a minimum buffer before vapor escapes.

    Plus, there is an advantage to tempering the water for your reflux condenser. It prevents you from dropping super cooled reflux into the column. If the reflux is too cald, it is possible to flood just the top of a packed column.

    On a Keg, 3" packed column, that's about one liter a minute year round.

    DAD... not yours.. ah, hell... I don't know...

  • @CothermanDistilling said: been there, done that, got the t-shirt... Thermostatic Valve Installation on Product Condenser

    I'm sure that this has already been thrown out there but I couldn't find it:

    At $135, wouldn't adding an additional long PC be a relatively cheap way to help with warm distillate? I've kinda already resigned myself to that fact along with a Super-Dephleg to help with my warm water. Then again, if the "cooling" water is 90f all of the water in the world won't get the spirit below that number.

  • This is one of those interesting issues.

    Warm distilate is better for airing some say. However, if you make your cuts on a hydrometer then you might want to cool your distilate to the calibration temperature for convenience.

    So long as no vapour gets through the PC you can work around the other issues.

  • I live in an area where water shortages aren't really possible, so I don't worry too much. But as a test the other day during a 3 stripping run session, I just let the water rip (basically 1/4 open is ripping for a 2" stand PC). The whole thing was cold, which I know is too much, but with ~45F water temps, I could knock down 11kw on an open 4" column and have cold distillate at ~12l/h or so running from 10% TPW. Pretty impressive for the little guy. I can't keep the column at 11kw thru the run due to foam, so I generally run it about 7kw which will only foam half way up the column (total is ~45" or so). At that power, a trickle of 45F water will give me cold distillate with warm water output from the PC. Cold ground water is a beautiful thing.

  • Very helpful information, guys. I think I'll stick to testing the PC temp by hand for now, measuring temp at the parrot and trying to keep the distillate at 20°C would also be a good idea, I wish I had such a combined alcometer with built in thermometer...

    I consider myself a newbie - Thank you for your patience!

  • I use my PC water and feed it to the RC. Exit temp is around 30C and no issues collecting

  • Has anyone ever thought of taking the exit water from the RC and mixing it with the cold input to the PC using a Y connector?

    My waters really cold and I can't get my product above 15°c

    I'm going to give this a try, using a single cold input source and a Y connector to split the cold input to each codnensor, a valve on the RC output for controlling reflux, then add this output to another Y with cold to the input of the PC, might have to be careful it doesn't stop the flow though the RC, but I'm thinking so long as there is a lower pressure though the PC it won't stop the flow though the RC

  • @Anavrin you might be slightly mixed up. Your RC exit is supposed to be HOT. You don't want to feed that into your PC. Splitting the cold feed and then combining both exit waters is fine though.

    Most folks that feed PC exit into RC input, do so in an attempt to reduce the sensitivity of the RC by feeding it with warmer water. Or because they don't wish to bother with independent flow controls.

  • Yes @Myles I know, but here's my thinking, the flow through my RC during a spirit run is only a trickle anyway, and my water input to my PC is too cold to get the product output at 20°c, I can't get above 15°c at the moment. Can't do any harm to give it a go :-)

  • edited March 2015

    Sorry I miss-read the previous comments.Yes you can do this in your situation but I would also add in a few extra components.

    1. Most important a non return valve between the PC input and the RC output due to the pressure differences.

    However you are missing an easier option here. All you need to do is to add a flow control on your PC output. Split your cold input and have separate PC and RC return lines each with flow control. That way you can control your product temperature with ease. It is my standard configuration.

  • edited March 2015

    Already have separate control valves, my PC is a 3ft Liebig and with its valve closed as far as I dare my product is still too cool.

    I did consider a non return valve but figured the flow through the PC will be higher than the flow in the RC, higher flow = less pressure so the output of the RC will always travel through the PC and not the other way round, I still might get one to be on the safe side but I'll try it without first :-)

  • @Anavrin - You could also use a thermostatic valve on the distillate temperature.. the valve I use is 25C-65C, all I would have to do is place the bulb in the distillate path instead of the coolant outlet and unscrew the adjusting knob all the way and I have 25C distillate coming out...

  • @Anavrin said: Already have separate control valves, my PC is a 3ft Liebig and with its valve closed as far as I dare my product is still too cool.

    Sounds to me like you need a 2ft condenser. ;)

  • @Myles said: Sounds to me like you need a 2ft condenser. ;)

    It's on my to do list, it's actally 85cm long and I'm going to reduce it to 60cm :-)

  • edited March 2015

    How cold is enough? I'd say taking your distillate colder than the closed cup flash point is probably unnecessary. Otherwise, you decide.

    Thought it would be helpful to share some of the reasoning behind my comment above. Realistically, the fire and open cup flash points are important for the hobbyists. For the commercial guys, below the closed cup flash point pretty much guarantees no vapor release. Above the Open Cup and Fire Points you are releasing vapor.

    image

    Flash Point - A certain concentration of vapor in the air is necessary to sustain combustion, and that concentration is different for each flammable liquid. The flash point of a flammable liquid is the lowest temperature at which there will be enough flammable vapor to ignite when an ignition source is applied.

    Closed Cup Flash Point - In the Pensky–Martens closed-cup flash-point test, a brass test cup is filled with a test specimen and fitted with a cover. The sample is heated and stirred at specified rates depending on the material that is being tested. An ignition source is directed into the cup at regular intervals with simultaneous interruption of stirring until a flash that spreads throughout the inside of the cup is seen. The corresponding temperature is its flash point.

    Open Cup Flash Point - The Cleveland open-cup method is one of three main methods in chemistry for determining the flash point of a petroleum product using a Cleveland open-cup apparatus, also known as a Cleveland open-cup tester. First, the test cup of the apparatus (usually brass) is filled to a certain level with a portion of the product. Then, the temperature of this chemical is increased rapidly and then at a slow, constant rate as it approaches the theoretical flash point. The increase in temperature will cause the chemical to begin to produce flammable vapor in increasing quantities and density. The lowest temperature at which a small test flame passing over the surface of the liquid causes the vapor to ignite is considered the chemical's flash point.

    Fire Point - The fire point of a fuel is the temperature at which the vapour produced by that given fuel will continue to burn for at least 5 seconds after ignition by an open flame. At the flash point, a lower temperature, a substance will ignite briefly, but vapor might not be produced at a rate to sustain the fire.

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  • Thanks for that @grim great info there

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