Those are nice, and there are some made by "Circle Seal" which are great also..... my problem is finding an online supplier that carries those valves, does anyone know of one?Quote:
Originally Posted by G H Z
Those are nice, and there are some made by "Circle Seal" which are great also..... my problem is finding an online supplier that carries those valves, does anyone know of one?Quote:
Originally Posted by G H Z
Hey guys... Gautam and I were talking about this thread just now and I had a few ideas:
I don't see why everyone wants to deal with the problem of running the pressure release down through the vacuum jacket and having to worry with having it evac'd again.
If you have a cork with two holes in it, one in and one out:
Basically you have a small air pump with a sprung ball release valve (aka manual boost controller) on the line to relieve any excess pressure above set amount(5psi maybe?)
http://www.importevolution.com/images/joep.jpg
Then in the other hole(out hole) you have the liquid line that goes to the bottom of the dewar and feeds the line going to the outlet.
Then all you need is a brass ball valve and whatever tubing you would like with either flared copper tubing or maybe some NPT threaded small diameter hard pipe.
http://www.northernbrewer.com/pics/f...l-valve-ss.jpg
Like this... VERY ARTISTIC... schematic:
[IMG]http://i34.photobucket.com/albums/d1...ewarpump-1.jpg[/IMG]
I've had that same idea, the only thing I wonder about is whether or not it would be an issue to be pumping straight air into the dewar.
Why the pump at all? The dewar will pressurize itself and you won't be warming the inside with 'Hot' room air loosing more LN2.
What issue would that be?
Well, with the relief valve you will just be bleeding off n2 constantly without a pump... with the pump you will bleed off air only.Quote:
Originally Posted by G H Z
Their's no need for a pump, because it doesn't matter if you're bleeding off N2, just as long as their's enough pressure to make the LN2 flow up the tube.
I think I'm going to try this when I get my dewar, it's cheap enough to build, so why not.
Well, without a pump you aren't guaranteed constant flowrate. LN2 might not evap fast enough to support the flowrate of LN2. Actually, I would think that there is no way that it would. If so then you would lose ln2 at a HORRENDOUS rate even with a foam cork because it allows evaporated N2 to escape.
I say no way to stay constant flowrate and keep pressures at a decent level at the same time without a pump or a heater in the dewar.
Read K|ngp|ns post on page 1
Even though he states that the built up pressure will be plenty to flow LN2. If it were enough to flow it at a CONSTANT rate for use in a setup like the Italian guy that had the 1M record for a bit it would have to have a pump.Quote:
Originally Posted by k|ngp|n
He states that it bleeds every now and then. So, it has to be building pressure slowly enough that its not a constant bleed. In order to hold constant pressure while flowing it would have to vent constantly.
Anyways, we are talking about something like a 12v bike pump or automotive tire pump. Like 15-20 bucks.
Or, if you have a tanked air compressor, you can regulate the outlet to very low pressure and low flow (basically infinitely variable from HUGE amounts of flow to a trickle if setup right).
Maybe you should inform KP that the system he's been using for quite some time doesn't really work :rolleyes:Quote:
Originally Posted by Eightballrj
I dont' think anyone intended to go through the vacuum jacket with anything, KP's design uses a rubber stopper with 2 holes, one for the flow and another for pressure release.
Quote:
Originally Posted by boshuter
Check first post again...
http://tweakers.net/ext/f/37e4bd9909...c153b/full.jpg
About Kingpin's setup... Gautam says that he doesn't dispense directly into a pot. He uses it to dispense into whatever he pours with.
SO... his setup is used for a different purpose and does its job at that purpose quite well. However, the way I am proposing has a different use.
Basically the pump is a luxury... if you had a pump you will ALWAYS have THE ABILITY TO HAVE constant flow rate even if you had the out line t'd to gpu pots also.
You could use a higher pressure and have constant flow rate for a certain time period. But, once temps stabilize in the dewar the evap rate drops drastically. So, after it stabilizes the flow rate will drop due to not being able to keep up with a constant release of liquid.
I understand that I don't have LN2 benching experience, but I am the lab technician and computer technician for the Mech Eng department and we have a cryogenics testing laboratory. So, I have played with LN2 a bit.
Yeah I'll be the first to admit that this stuff is all way over my head but I think eightball has some good ideas.
TBH as far as LN2 benching goes, I feel that systems which inject it directly into the container are going to become very big in the future. Some Italians and FUGGER have already used similar systems. The next step would be to vary the pressure on the fly in order to hold a constant temperature, which would still require plenty of skill and user interaction. It'd waste a lot less LN2 though.
The Italians system is far different than any other pot out their, they use cartridge heaters built into the pot to maintain constant temps. They just fill up the pot and very the load on the heaters to keep son
Their's no need for a pump, you're making the assumption that you need a constant 5 psi pressure to keep it pumping. So assuming it's less and you set the bleed valve to 5 psi, the bleed valve won't affect the ability to pump ln2, just keep the dewar from bursting.
I'm not sure wheter KP pumps the LN2 into another container before pouring into the pot, but that would make sense to me. I'm guessing Fugger used the same system when he benches with LN2. It's still a hell of a lot easier than picking up a dewar and pouring from that into a thermos, etc.
Btw, if you look at the systems MVE makes to dispense LN2, they're based on internal pressure.
Stapler... that's the difference, I am saying that if you are benching and you don't want to pour then a pump would be nice.
Where the problem is, is that just because you set the bleeder to 5psi that doesn't mean that there will always be 5psi in the tank.
Think of it this way:
If you open up the valve and the volumetric flow rate of the LN2 into the pot is higher than the volumetric evaporation rate, then you WILL have a pressure drop over time. I mean if you are benching 1M Pi then thats never a problem. But, if you are benching for minutes at a time (3d06 or 32M) and you will need a to be able to have a constant flow rate so that you are not constantly having to change the valve's opening (therefore changing ln2 flowrate) to keep the proc out of cold bug and yet still sustain the overclock.
That's where a pump would be nice.
ANYWAYS, I don't see why everyone is harping on the pump. It is FIFTEEN or TWENTY DOLLARS!!! OMG we are talking about multi thousand dollar rigs and multi hundred dollar LN2 setups... This is a fart in a tornado!
If you don't want a pump you don't HAVE to have it. But, it will allow for a constant pressure regardless of the flowrate(given that the pump will have to have a flowrate equal or greater than the outlet flow) required by the pot or pots in the system.
BTW, the MVE dispensing systems aren't necessarily made for a required constant flow. That is a system that you will be able to transfer LN2 from a dewar to another holding container. That will work perfectly fine. But, we are talking about a finite amount of transfer available.
The pump system could also be used in a setup using LN2 in flow to cool a block similar to a waterblock if someone wanted to try that.
Waterblock has been tried by another Italian Team, it was actually pretty successful.
Unless you've got a pot like Alex_Ta's, I don't think their's much point to constant flow rate, and even with that pot you don't need it, you just dial back the cartridge loaders.
Exactly, Eightball, your idea is a good one, but I believe you are overestimating the "flow" required for what we want to do. Keeping a pot at temp is a matter of trickling a little ln2 in now and then, not a constant flow. What you are proposing would be fine is something that requires the "constant flow" you are trying to achieve, but the bottom line is, we don't need constant flow.Quote:
Originally Posted by Stapler
A simple setup with a bleed valve and flow valve is all that is required, so I really can't see the point to complicating it with pumps or heaters.
BTW.. I didn't see that diagram with the vent going through the vacuum jacket in post one, I'm not sure why anyone would want to do that, a rubber stopper with 2 holes in it is all thats needed.
Quote:
Originally Posted by boshuter
Very true, I guess that's where my lack of LN2 benching experience shows. Well, if I get a dewar then I will probably try it with a little pump when I get my setup started, haha. I guess I am just stubborn like that.
Anyways, if anyone else builds a setup please make a write up with pics and link to it in this thread so we can all see it and see how you like it.
Extera check this site :
http://www.hennyvanommeren.nl/produc...groepnr=65.150
They have some kinds of dewars and other stuff so maybe they have a spare valve.
thanks for the info ramaistro (better late then never)
after a call to henny van ommeren, they told me to contact a company called pirtek. I will call them again on monday, the'll prolly have the overpressure release valve...
A little bump here...
The company I called can deliver me a over-pressure relieve valve.
But I wondered, howcome that the part of the device thats outside the dewar isn't frozen on al the pictures? I mean, I don't think it should be frozen, that would be a little dangerous. But why doesn't it freeze?
And do I need a relief valve that keeps working at very low sub-zero temps?
Quote:
Originally Posted by Extera
It does sometimes if your using the dewar like mad shutting the valve on and off frequently, the pressure blow off valve will be consantly blowing off gas and it will freeze from time to time. Same goes for the pump. When doing 06 say with 3 units nitrogen is almost constantly flowing out of the head so that will completely ice up as well. By the time you get through all 30 litres, the whole head is usually encapsualted in ice :D