Does it have to be a NEEDLE valve?

Arthur · Post by **Arthur** » Sat Aug 26, 2006 5:14 am

I've decided on the Bokabob design and am now sourcing the parts. Saw this 1/4" ball valve on ebay, is it suitable?

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... %3AIT&rd=1" onclick="window.open(this.href);return false;" rel="nofollow

Thanks

PseudoX · Post by **PseudoX** » Sun Aug 27, 2006 5:24 am

The idea of the needle valve is to allow precision control over the offtake rate (as in like 1 drop per second, to take it down to 1 drop 10 secs).

The ball valve wont give you anywhere as much control. You can try it, but i reacon you will be kicking yourself later, as you wont have much control.

Well, thats just what makes sense to me.

rkr · Post by **rkr** » Sun Aug 27, 2006 9:34 pm

It'll work but the adjustment is coarse. One way to get it more precise is to attach a long arm/handle to the ball valve, just move it half an inch at the time at the far end.

Cheers, Riku

Arthur · Post by **Arthur** » Mon Aug 28, 2006 8:06 am

Thanks for the replies. Not quite sure why 1 per second is wanted when 10+ drops are available, something to do with the other 'drops' going back for more refluxing?

I'll be using a mains output regulator on a hotplate, can get a lightbulb to glow less than a candle with it so no probs (I hope) getting 1 drop per 10 secs if that's what I want.

rkr · Post by **rkr** » Mon Aug 28, 2006 9:07 am

Arthur wrote:Thanks for the replies. Not quite sure why 1 per second is wanted when 10+ drops are available, something to do with the other 'drops' going back for more refluxing?

I'll be using a mains output regulator on a hotplate, can get a lightbulb to glow less than a candle with it so no probs (I hope) getting 1 drop per 10 secs if that's what I want.

Power control works for RR controll only with constant cooling CM system. Unless you know exactly what you are doing with power regulators I suggest you study the subject further. It's quite likely that you'll either fry the regulator or create disturbances to electric mains network bringing some more or less official people to your door. Those lightbulbs are usually 40-100W while your heating element is likely from 1000 to 2000 wats.

- Riku

Arthur · Post by **Arthur** » Mon Aug 28, 2006 11:06 am

What's RR control?

The regulator is from Maplin, it's not a light dimmer. The blurb says it'll handle 2.6 Kw with a suitable heatsink (which I gave it). It's supposed to turn on/off at zero voltage on the mains but yep it is a bit dirty, it stuffs up my self built usb soundcard when running the little pot still. Haven't put my scope on the mains yet, will do that before using it wiith a bigger load than 480w.

If it's real bad I'll look for a true zero voltage crossover regulator, now I'm used to using a regulator, too cool to do without, love the control it gives me.

AllanD · Post by **AllanD** » Fri Sep 01, 2006 9:35 am

"RR" would be forum shorthand for "Reflux Rate"

AllanD

rkr · Post by **rkr** » Fri Sep 01, 2006 12:33 pm

AllanD wrote:"RR" would be forum shorthand for "Reflux Rate"

AllanD

Reflux Ratio. Almost the same thing. Amount of reflux returned to column per amount of reflux removed as product.

Cheers, Riku

Arthur · Post by **Arthur** » Fri Sep 01, 2006 7:34 pm

Ahhh... so the higher the reflux ratio the purer the product...

After thinking about the regulator, I've decided I don't want the potential problems and altering the water flow through the condensor gives enough control for most here so good enough for me.

I have now sourced a 1/4" needle valve but the seller doesn't know what it's made of. (So he says.) Cheap enough for me to take a chance and if it sticks to a magnet I'll bin it.

hornedrhodent · Post by **hornedrhodent** » Sat Sep 02, 2006 2:53 am

Arthur wrote:Cheap enough for me to take a chance and if it sticks to a magnet I'll bin it.

Dont bin it - It'll give you a very precice control on your cooling water.

fahdoul · Post by **fahdoul** » Sat Sep 02, 2006 3:02 pm

You are overcomplicating things - this is not rocket science. You can buy a suitable brass needle valve at almost any hardware store for about $3.

I like the tube compression fitting style that use the little swage rings, since they make it very fast and easy to try modifications like adding a Leibig or changing the output tube. I use the same one on my 1-1/2" and 2" columns, since switching it back and forth only takes a minute.

Arthur · Post by **Arthur** » Wed Sep 06, 2006 2:10 pm

fahdoul, most of us here in the UK us tinkerers can only dream of hardware stores like you have.

The valve arrived and it's stainless, so far so good. For controlling the water flow I was going to use the ball valve on the washing machine hose but thanks to hornedrhodent I'll get another needle valve for that.

Spike · Post by **Spike** » Fri Sep 08, 2006 4:39 am

Has anyone any experience of nickle plated brass needle valves? I have a couple but not sure if I have to clean them up before using them.

Spike · Post by **Spike** » Fri Sep 08, 2006 4:50 am

Follow-up : These same valves (Hydraulic Needle Valve 1/4" BSP Ports made by UCC (#250024100270)) are currently on eBay at GBP 4.00 each (RS Components normally sell for around GBP 19.00 each). Bargain if they are usable with Eth.

stoker · Post by **stoker** » Fri Sep 08, 2006 6:09 am

I think it's this
are you sure they are nickle plated?
I thought those were chromium?

Spike · Post by **Spike** » Fri Sep 08, 2006 7:05 am

According to the RS Catalogue they are. In fact the catalogue picture makes them seem shiny whereas the eBay pic shows them dull, pretty much as you would expect for nickle.

Either way, I expect the quickest and most thorough way to clean them up, if it is necessary at all, would be to plate the nickle off the valves onto something else.

Spike · Post by **Spike** » Fri Sep 08, 2006 2:57 pm

When I re-read my last comment I realised the most obvious alternative is just to buy SS or brass valves in the first place. I can over complicate things at times.

Arthur · Post by **Arthur** » Sat Sep 09, 2006 7:44 am

That's exactly what I've got.

Edit:

I took a dremel to it and applied the sanding drum. I dug in over 1/16" and it's bright shiny metal.

Have now noticed a glint of brass colour. Don't know how I missed it at first.

So.... Is nickle safe? Will the ethanol destroy it and if so, is the brass underneath likely to have been coated with lead?