Need help for a stupid mistake

Noellaflamme

Noellaflamme

Well-Known Member
So, I finally got a dewar and some liquid nitrogen for my AEBL, and long story short, 2/6 knifes are niw stuck inside... So far my attempts with a magnet and drain snake has gotten me nowhere...

I know what I did wrong and wont do this again, but has anyone else dealt with this problem? Should I just try turning it upside down when its empty and shake them out? Drain it into a temp cooler?

Thanks for any tips.
 
Carefully pour into a cooler then as you said upside down to get them out. You will loose some liquid due to gassing off but as you said will learn.
 
I agree with the above.
But can you explain how it happened. I plan to go that route soon and your expected would certainly be appreciated.
 
opaul said:
I agree with the above.
But can you explain how it happened. I plan to go that route soon and your expected would certainly be appreciated.
Click to expand...
So I made a hanger to dip them in, but because of the comination of hole placement and shape a few got stuck, and in the process of trying to free them up, 2 came loose unexpedidly and fell in.

My take away is more hangers, less knives per hanger
 
When i do cryo, I twist a loop in some wire, usually just pull some from my mig welder. I put the loop over the point of the blades, I usually bundle several together, then wrap the wire around the blades several times and run the wire through a hole in the handle of the blades. I put the blades in the dewar point first and bend the end of the wire over the mouth of the tank. This keeps the blades together tightly to help prevent warp and makes it almost impossible to lose in the tank.
 
I use the pin or thong hole in the butt or tang of the knife to run some 1/16 wire though it and make a hook so it will wrap around the wire. I can hang 8 bundles in my semen tank and then individually pull a group up the neck at a time when ready.
 
Hey , Get a spool of thin copper wire wrap it around you knives ... Reusable , leave it long , 3 feet long pieces then you can always fish it out
do one knife at a time to get even chillin . heat and extreme cold effect magnetism .
 
Most are using 10-30L dewars. 10L is cheaper to get and fill if your blades will fit into it height wise, but won't hold long. I have an 18L with a 2" opening (actually slightly under 2" to get a blade in and out) and a 30L with a 2.5" opening. I got both of mine for free at work (University setting) when they were throwing them out, just needed to order the foam plugs! Local colleges/university may use them in labs, health centers, etc, so it pays to check with them! If they haven't used them in a few years, they may get rid of them. My university has the big rolling tanks and often don't need to hold items in Cryo for extended time periods, so they didn't need the dewars and were cleaning out their storage areas. The health center has them still for warts/skin tag freezing removal.

Just check the inside dimensions; dewars have a long neck section, so if you put a long blade in, only part of it will be in the liquid and the remainder in the neck. The vapors will still cool, it will just be slower, or dip, soak a few minutes and then flip the blade around?

You may be able to find some on FB Marketplace?

Larger than 2" opening means the LN2 will not last as long. I am paying around $13/L for LN2 here, so I want to have it as long as possible and try to HT in batches when I do have it to get my moneys worth out of it! Trying to find a farm supply or something around here to get it filled instead of the welding place. A 3" or 5" opening would be sweet, but the LN2 would off gas pretty fast out of it!

My 18L is an extended time tank (more insulation), so it loses less LN2/day due to off gasing; I went 5 months on my last fill up! The MVE 30L off gasses more with the wider opening, but has almost twice the capacity. Buddy has the same one (MVE 30L) and gets 5 months from his fill up, but he puts twice as much LN2 into it!

I picked up a spackle mud tray if I need to pour LN2 out for blades that won't fit into my Dewar as well as the big massive cold gloves. Need to be careful since it will boil violently when doing so!! I haven't tried pouring yet; I was going to put water in my 30L and try pouring front that (also to clean out the dust and stuff from inside of it!) to get the hang of it before trying it with LN2.

You can also use Dry Ice and Graves alcohol or Denatured Alcohol to get below -100 or so for a cold treatment, which will help reduce the RA. I did that with some Magnacut blades that were 24" OAL and 2" wide that wouldn't fit into my dewars, HRC was right where it was supposed to be for the Aus. time/temp that I used.
 
How deep is your dewar? Would a pair of long reach pliers work?

I had a similar thing happen with my dewar. There's a small raised metal bracket in the bottom of mine for holding sample tubes. I had about 4 or 5 small fixed blade clamp together and lowered in with some bailing wire, but the handle of my c-clamp somehow wedged under the bracket on the bottom of the tank. I had to stick a steel rod down the opening of my dewar to knock it loose and I was then able to get my blades out.

At any rate, I picked up a hand full of these tiger clamps:

As they have a much lower profile than my C-clamps and can go in and out of the neck of my dewar much more easily.
I still make sure to wrap my wire a couple of times through the clamp or my knife tangs so the wire doesn't slip off.
 
Taz537, what part of the world are you in for $13/liter? That's expensive. When I first started buying LN a few yrs ago I was paying 50¢/liter. Now it's up to 80¢ (USD) last I purchased a couple months ago.

5 months holding? That's NICE - my 10 liter dewar only lasts perhaps 6 wks or so.
 
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