In need of a dewar lid picture

B . Buxton

B . Buxton

Joined
Jul 8, 2001
Messages
3,623
My ol buddy Ron Duncan located a dewar for me but it needs a lid. I've looked on ebay for pictures and seen some that look like long plugs but I can't tell if there's a seal or what where the lid meets the tank opening. The ones on ebay have grooves down the sides, are these for venting or are they just openings to accomodate hanging wires inside. Are the lids pretty air tight? If anyone could take a couple close up pictures of there dewar lid and send them to me I would really appreciate it. My e-mail address is camper@yhti.net

Thank you,

Bill
 
I picked up a fairly good sized Linde dewar off of ebay last year. Is was a specimen/sperm storage dewar but came without hanging holders.

The lid looks like a sauce pan without a handle and in the center is a round length of foam attached at one end, in the center of the "saucepan". The throat of my dewar is about 7" deep by 2.5" in diameter and the foam plug is about 6" long and fits, not snugly, but with a fairly close tolerance in the opening. The foam plug has the grooves in it to accomodate the hangers but they could probably be filled in with something to minimize evaporation. No pics right now but will try and get some tomorrow.

(edit) There is no seal and not very air tight. The pan just rests on top of the throat of the dewar.

Allen
 
Thanks Allen, I was going to use one made of styrofoam but it sounds like yours has a spongy foam plug, if it's spongy foam I wouldn't think it would need hanger slots for the foam should be flexible enough to allow room for the hanger wires. But I have no idea how much venting this stuff needs. If you can get a picture I would really appreciate it, just send it to my e-mail address.

Thanks again

Bill
 
Bill, Wouldn't the place where your going to get it charged be able to tell you what you need for a lid? I just woke up so I may have missed something.
 
Ray, you would think so wouldn't you, But I called them yesterday and they talked like they didn't care or have a clue, kind of like duh " My favorite colors clear mentality" . It often amazes me how some people have managed to get a job, and when they do ,managed to hold onto it as long as they have. Damn hillbilly's :confused: :jerkit:

Thanks for the suggestion though,

Bill
 
Bill, It ain't just hillbilly's. If its an asshole it must be. They come in all shapes and sizes. I'm sure you ran into a few in your other life as a carpenter. One of the main reasons I don't miss that other life.
 
Thanks Darren I would appreciate that.

Ray, yes there were a few in my other life too, but I still miss the good guys. I just don't understand why anyone would have some idiot run their business, Go figure.

Bill
 
My father's old one left over from dairying was a loose fit. The reason for the slots in the fome is that at minus 300 deg.F. the fome is nolonger soft, but hard as a brick. It does need a bit of ventialtion, I might would fill the hanger slots, as long as the cap was a loose fit. Tanks are listed by time, 30 day, 60 day, 90 day and I beilieve there are longer times availible.
 
Bill,

I sent you a zip file with these pictures in it but just in case here they are hosted at PhotoBucket.

The little yellow nub is a grease filled cup which I believe acts as a pressure release valve.

This particular Dewar is about 17" in diameter and stands about 24" high.

Hope these help.

Allen

DewarLid3.jpg

DewarLid2.jpg

DewarLid1.jpg

Dewar2.jpg

Dewar1.jpg
 
Bill,

I forgot to mention, the foam plug is not soft or spongy. It is firm like a styrofoam but very very lightweight. Lots of air gapping. High density foam may not have the requisite insulating qualities.

Allen
 
You can probably contact a local lab supply store or check out Fisher Scientific or PGC Scientifics for replacement lids.
 
I'd imagine the 'foam' is some sort of spun glass material similar to the refractories used in our forges. Honestly, I'd be careful with a DIY lid, as you are dealing with some extreme conditions. And the venting as others have mentioned is absolutely necessary. Another thing to note is companies maybe unwilling to fill any dewar they deem unsafe, or appears to have a makeshift lid.

-MJ
 
Update on the foam, I've been doing some searching and that is referred to as the 'necktube core', and I've found several manufacturers offer rebuilt ones, just do a google search for it. That and the brand/specs of your model should help you find a direct replacement, that and a cap would still be at least half the cost of a used dewar on eBay and much safer then trying to build your own.

-MJ
 
I made one for ours at work out of Styrofoam.
I found a tall aluminum can the right size (some kind of hairspray), cut it with my Dremel abrasive cutoff wheels, cut a few notches in the edge for teeth, then used it as a hole saw.
Slow cutting, but it did work okay after I glued it to a suitable lid...
 
Mine has a styrofoam plug similar to the one in the picture. The slots are there to accomodate the round rods that hold the specimen cans. The cans hang inside.

That little plug on the side is where the manufacturer drew a vacuum between the interior core and the outer can. Protect that plug or you'll lose your vaccuum.

In use, mine has an aluminum cap/cover that fits loosely over the strofoam top plug.

How do I know this??? :jerkit:

I just bought mine off Ebay and read the lable.:D
 
Don,

That's interesting. I did not know that the little plug thingy is used to draw a vacuum. Mine has a little plastic cap over it but the opening is filled with some sort of grease. I've not taken the grease out to see what is underneath.

Do you know how much vacuum is pulled? Are there are services that will test and verify the proper vacuum and redo it if needed?

Allen
 
You must log in or register to reply here.
Back
Top