Cryogenics around Merseyside?

[johnheritage]

I'm going out on a limb on this one!

I do chemistry experiments quite a lot at home and one of the major problems is getting things cold.

When I'm using a vacuum pump for example, it'll tend to make anything remotely volatile boil at a very low temperature. I use special laboratory glass condensers, but there is a limit to how cold I can get them and how long they stay cold for. As a result, volatile material will pass straight through them under vacuum and into the vacuum pump, where it either corrodes the pump or sits in the pump oil, ruining the pressure the pump can reach.

I could really do with some dry ice or liquid nitrogen. Liquid nitrogen in particular is so cold it'll liquefy or solidify anything trying to get through the dewar.

I have an account with BOC and have called the others, but the issue is that they only supply bulk bags of the ice or tanker truck delivery of the LN2. Since I use it on an infrequent basis, the stuff would boil / sublime out the window too quickly in between uses; even if I use dewars to store it.

Is there anywhere around Merseyside that I could possibly visit to get a flask full of either when I come to do something?

All the best!
John

 

[cumbriasteve]

You could have used my workshop last January, would have loved some LN to warm the damn spot up.

OK..I am a million miles from knowing anything about your post but before I retired we did mess about with an ion chamber and used to make ice plugs using Co2 through an insulated collar of some type, that obviously got well cold and frost appeared on the outside even.... I suppose you may have already eliminated that method as not cold enough...was just a thought.

 

[shenion]

Look at suppliers of food service equipment. Some may have dry ice.

Here, dry ice can be gotten at most supermarkets.

 

[Omniata]

Hire a CO2 bottle from BOC with a "dip tube"...

They do smallish ones for low cost, they do an "R" sized cylinder which should be pretty similar to a "Y" sized Argon bottle...

Then simply get a bit of high pressure hose, they can supply , and vent the cylinder into a wooden box with brass mesh covering some holes in the side...

Hey presto, dry ice blocks, that's how we used to make them at University in the lab...


NB:// Do it outside though


Also if you've got some thick gloves you can do it with a pub bottle upside down into a Hessian bag



I'm a bit of a chemistry fanatic myself, although I generally deal with stuff around room temp, or hot, you've got me intrigued

 

[johnheritage]

Thanks for the replies guys. I have been thinking about the dip tank option.

@cumbriasteve

An ion chamber at work? What were you doing?

@Shenion

This is one of those differences between the UK and US, and a pain in the ass at that as well. I've literally never seen a single place selling it from a shop. The plumbers seemed like a good bet, but they're now using cartridges of something or chiller units.

@Omniata

Shame I took the manifold for the paintball guns apart and started sticking bits of it on fridge compressors. Now I'll have to buy some new bits.

I may start buying lecture bottles. Even the small argon cylinder I have from BOC takes me about a year to get through, so the rental is the main cost of having it, as opposed to the gas as it is for welders.

What I'm making varies vastly based on the topic of interest at the time. A while ago I was trying to make electroluminescent paint. That's the stuff they make VCR displays from that glows when an electric field is nearby, then stops as soon as the field is removed.

Some nerds wanted to build big eye catching displays with it at home.

One of the oldest and most basic methods is Zinc Sulphide doped with Manganese.

To try and make it repeatable by a wide community, I avoided using anything that'd need a lab supplier account or buying anything particularly special. So I took apart some alkaline batteries. The casing is 'pure' zinc. So I scrubbed those clean, washed them in sulphuric to remove any contamination from the paste and to etch off the surfaces to expose clean zinc, rinsed then, then dissolved in them sulphuric acid. I filtered that through coffee papers to remove the remaining bits of metal, then boiled the water off to obtain an impressive yield of pristine white sulphate. I then heated that with sulphur from the pet shop to reduce it back to the sulphide.

For the manganese, I rinsed the paste with copious amounts of water to remove the alkaline electrolyte (KOH or something similar) and filtered it through more coffee papers. The paste is then manganese dioxide with activated carbon. I poured hydrochloric over that (brick cleaner without surfactants in it), releasing a large amount of chlorine in the process, to end up with manganese chloride (water soluble). I could then filter the mess again to split it from the activated carbon, which worked fine.

The manganese is heavily contaminated with iron. It should be bubble gum pink, but was filthy dark brown from iron chlorides. Getting it pure without resorting to fancy lab gear (which the average electronics nerd would not have) was tricky. But I found a neat method online. I removed about a third of the filtrate, added an excess of KOH (NaOH would also work) and the solution turns into a big gooy mess as the insoluble hydroxides of iron and manganese fall out. That got washed, multiple times, with water to remove the excess base, then dumped back in with the original filtrate and I blew some air through it overnight. The hydroxides selectively precipitate out the iron contaminant, but not the manganese. Filtered it again, bingo! Pink, reasonably clean manganese chloride. Recrystallised to clean it up a bit more.

I built a tiny ball mill out of Lego and a medicine bottle to homogenise the minute quantity of dopant into the sulphide.

The problem was driving the manganese into the sulphide. It's supposed to take hours and at a temperature that will melt borosillicate glass. Not many chemists have quartz, let alone anyone else. The methods also tended to use very odd atmospheres, like hydrogen sulphide and carbon disulphide.

I still haven't got that bit worked out yet. I'm about to get a tube furnace. So I will test the materials I've made to check if they are pure enough using the advanced method first, then see about simplifying it to something people can do at home with bits of nichrome wire.

I made a few litres of benzene quite recently. After distilling the benzene it's self, it leaves a sizeable chunk of benzene derivatives in the remains. I think I've got a few hundred grams worth of it. It fluoresces and it's nuclear orange. I already know this method produce biphenyl, so that'll be in there. The fluorescence may be benzophenone, and the orange... I think that may be a ferrocene like side product. I'll be vacuum distilling it under argon at some point soon (once I get a new seal for my vacuum pump) to see what I can fractionate out of the gunk.

Another recent experiment was making potassium without having to melt anything or use electrodes. It'd done in a high boiling solvent, like parafin, and uses KOH, magnesium and a small amount of alcohol. Which is a really novel trick, because making alkaline earth metals usually entails molten baths and currents; extremely dangerous.

If the tube furnace is up to it, I'll have a go at making some carbon disulphide when it turns up.

I may also have some work to do with biofuels, but that's currently in the planning stage.

The cryogenics are necessary for boiling off solvents typically, to make sure they condense well. Or for liquefying gases. E.g. hydrogen chloride is really handy for making anhydrous chlorides but dealing with gases is a ****** when they're coming out of a generator rather than a nice flashy cylinder from BOC (Check out how much a Monel regulator and manifold is from Sigma, it's eye popping).

I did a quick experiment just recently about this actually.

Mixing 1/3rd salt with powdered ice will get around -20C. And it's a latent heat change, so the temperature stays still as the ice melts.

Then I found an old army training manual that mentioned using snow and dilute sulphuric acid, and that it would reach a chilly -67C. I tried that three or four times, even precooling everything in the freezer overnight, but couldn't for the life of me get it to work. I suspect the error is in what their version of 'dilute' is. A number would have been very helpful.

I've also seen laboratory chillers on eBay. A lab 'deep freezer' is on there right now, for about £300. It's maximum temperature drop is to -35C. Well... if you press the superfreeze button on your domestic freezer, it'll do the same thing, but it's hundreds of pounds cheaper.

The lab chillers also cool directly using a pump, like a fridge or freezer. That means that whilst they can reach -30, they have zero pumping capacity at that temperature; the temperature will climb from that as soon as the thing connected to it gives out or transmits any heat to it.

One of my current schemes is to get a chest freezer and fill it with ice bags or bottles of water, mixed with antifreeze so they freeze at -25 to -30C. Then add some pure antifreeze and a pump. That way, the temperature is not rising at all until all the packs of ice melt. And it's a few thousand pounds cheaper than the laboratory version that warms up.

I have a very big set of photos I could email you if you like.

I see you're in Chester, LP chemicals is around there. I think Prestons used to be as well.

 

[clem dog]

You could try some one who supplies semen for A.I. To farmers as they have flasks full of nitrogen, they could perhaps pour some off to you as and when you require.

It should sure be cold enough for your needs. It used to really burn my fingers lifting the straws out until I purchased a pair of tweezers to lift them.

If this was any use you could maybe get a flask that they would fill for you and then you could use this as you need and call them for a top up when it gets low.

At this time of the year, dipping in and out of the flask at least once a day I only need it topped up every two months.


Just my thoughts,

Clem

 

[johnheritage]

Of coarse, sperm.

The dry ice can come from a cylinder and nozzle, but the LN2 can't. So it's still worth me checking around.

In fact, my sister used to work at a veterinary school nearby. They had a man specifically for 'stimulating' the pigs. No one would use the cups he'd touched.

I've seen a guy managing to produce LN2 at home. He was German and using an immense and complex array of fridge compressors, each cooling the next in a cascade, to drop the temperature lower and lower. There are units like that for doctors clinics that fill a 1l flask per day for use on warts, by compressing the air and cooling it. But they'll be real expensive!

A fridge compressor can produce around or over 500psi. If CO2 is cooled to tens of degrees below zero, it'll liquefy under that much pressure. Then cool, significantly, if blown out of nozzle - as is done with the dry ice bags that go on the cylinders. I've wondered in the past if I could tap into the supply of CO2 coming out of the boiler's exhaust for that purpose, but the garage is such a mess and it's such a risky idea I've not attempted that... yet. It would be neat, to have an on tap dry ice maker running in the garage; no cylinders, available 24/7.

 

[cumbriasteve]

Thanks for the replies guys. I have been thinking about the dip tank option.

@cumbriasteve

An ion chamber at work? What were you doing?

I taught nuclear safety and the ion chamber was for demo purposes.

 

[johnheritage]

Ah right! That'd make you the third guy I've met involved in nuclear.

I bought my balance from a guy who worked at the Liquide Air plant and he was now doing some contract work on 'nuclear liquor' tank racks.

And one of my relatives is the H&S guy at one of the plants.

I'm desperately in need of cash, so if you know of any nuclear waste that needs shovelling, I'm your sponge!

 

[cumbriasteve]

Ah right! That'd make you the third guy I've met involved in nuclear.

I bought my balance from a guy who worked at the Liquide Air plant and he was now doing some contract work on 'nuclear liquor' tank racks.

And one of my relatives is the H&S guy at one of the plants.

I'm desperately in need of cash, so if you know of any nuclear waste that needs shovelling, I'm your sponge!

Well the storage of a small black drum of good bouncing waste costs £50,000 a drum for 10 years...have you got a garage going spare?

 

[Disco_Mark]

Have you investigated Air conditioning suppliers/rechargers? Our local independent guy has been known to supply lumps of dry ice for various uses.

just a thought that had not been suggested...
cheers
Mark

 

[graffian]

Ask someone who works in a hospital if they can get you some. I got a flask of it from a nurse. She didn't have anything to do with it at work, but she asked around and arranged for me to collect a flask of it.
An engine builder I know had it from BOC, he used to fill a polystyrene coffee cup with LN and use it to assemble press fit parts, unless I was there in which case it was used for cleaning the floor and other important things.

I asked around for dry ice, several people said they could get it but getting LN was easier.

 

[Drains]

Dry ice used to be easy to get from theatre lighting companies. Maybe now not so, since people use smoke machines these days. Could be worth a phone though.

 

[Lewis Medlock]

There's too many big words in this thread for me but I saw this on the telly the other night cleaning chewing gum off the pavement, I think it runs on dry ice so it can't be that hard to get hold of.

http://www.karcher.co.uk/uk/Products/Professional/Industrial_cleaning_systems/Dry_ice_blasters.htm



All the best, Jim

 

[Lewis Medlock]

Here you go, ask these lot for a cup full of the stuff, they're 14.2 miles away from Wallasey according to the AA

http://www.jordans.co.uk/CompanyIndex/w/we/wec/07268383/wecleen_uk_dry_ice_blasting_service_ltd.html

Jim

 

[johnheritage]

Thanks for the extra replies guys.

Jim! I've seen that on youtube, dry ice blasting. Didn't occur to me that there'd be one close by.

I know BOC do it, but they don't have it at the Liverpool branch so it'd mean ordering that little truck round. And that's going to cost a fortune.

All the time I'm out in the car I'm watching for tanks of it on site.

I'm not sure about the hospital option, as they're usually really picky about letting the public take anything related to the hospital so if they do give me some it'd probably only be once.

Theatre companies, that's a possibility but I suspect it's mainly smoke machines now as you say. Also, I doubt they keep the dry ice on hand, they probably buy it when there's a performance on that needs it.

I've asked at http://www.weldinggases.co.uk/index.php?_a=viewCat&catId=3 if he can get dry ice, LN2 or does CO2 cylinders with dip tubes.

It would also be useful getting some argon from him as the rent on the BOC cylinder is really high compared to the rate I use the gas.

{edit}

Just called BOC.

Waist sized cylinder (22kg) is £30 for the gas and £74 rental, with the VAT.

How does that sound? The rental seems kind of high. I'm going to end up having to sell a testicle to pay the BOC bills soon enough. Anyone need an extra testicle? It's used but in fair to good condition.