A freezer inside of a freezer inside of a freezer inside of a cooler insider a cooler

[2sac]

That's all fine and dandy but the ice cream would definetly be to hard to scoop.

[Tommy knocker]

Don't know about -100 but I can say that -40 is painful within minuts to any exposed skin.

[jonbailey19808]

I think this is being miss understood.

I used to work on a great deal of Cascade -70F freezers. They are nearly always reach ins or chest type. I have never seen a -70F walk in. It just is not a good idea to work on. I think it would be extremely dangerous too.

It sounds like his freezer with in a cooler etc is running normal freezer temps just does not want a temp change as you open the doors to walk in.

I worked in one place that i shall not name that did animal testing. If you went in one building you could not go into another on the same day..i asked why? they said if you contract a virus they didn't want to transfer it to the other blocks.
I asked them then why could i go in one the next day? They said you would know for sure you had one by the next day or you would be dead by then! Nice. I hope he was joking.

[koolkahuna]

I think this is being miss understood.

I used to work on a great deal of Cascade -70F freezers. They are nearly always reach ins or chest type. I have never seen a -70F walk in. It just is not a good idea to work on. I think it would be extremely dangerous too.

It sounds like his freezer with in a cooler etc is running normal freezer temps just does not want a temp change as you open the doors to walk in.

I worked in one place that i shall not name that did animal testing. If you went in one building you could not go into another on the same day..i asked why? they said if you contract a virus they didn't want to transfer it to the other blocks.
I asked them then why could i go in one the next day? They said you would know for sure you had one by the next day or you would be dead by then! Nice. I hope he was joking.

This particular cascade freezer in the pharmacy was definitely a reach in. NASA makes use of walk ins for their equipment testing, but I'm not sure that they even need that cold of a temp.

As per the virus situation, he had to have been joking or OH&S should be involved! You never know with some of those places. We used to get service calls at the agricultural/bovine studies department at a university where the cows had plastic doors installed on the sides of their stomachs by "veterinary surgeons". There were departments for other research there with SERIOUS security measures. Always made me wonder whether they were trying to keep people out or keep something in...

[Jbart]

This particular cascade freezer in the pharmacy was definitely a reach in. NASA makes use of walk ins for their equipment testing, but I'm not sure that they even need that cold of a temp.

As per the virus situation, he had to have been joking or OH&S should be involved! You never know with some of those places. We used to get service calls at the agricultural/bovine studies department at a university where the cows had plastic doors installed on the sides of their stomachs by "veterinary surgeons". There were departments for other research there with SERIOUS security measures. Always made me wonder whether they were trying to keep people out or keep something in...

We have quite a few different types of freezers at a cutting edge hospital I work at. Out lab has the -80C freezers, the CVOR unit keeps some of their stuff at -313F. The MRI low stage (recycled liquid helium) keeps the superconductors of the MRI at absolute zero (I love the whole superconductor theory). Our MEG also uses liquid helium but it does not recycle it, only vents it (manufacturer says it will void the warranty to put a helium recycle unit on it, weird I know). I am the resident HVACR expert at our facility (that just means I have a lot to learn about a lot of things) so I get to work on a lot of stuff.

[cmclifton]

About 10 years ago I worked on a system here in San Diego that had been running at -40 for years with no defrosts. There's a small ante-room that's kept at 20°C that you go into first, on the wall in that room is the control panel for the whole setup. Through the next door you enter into a 4°C room that has glass doors on either side. Behind those glass doors it's -40 +/-0.5°C at all times. No defrosts. Ever.

There's a small rack on the roof that handles the cooling for the whole system. Two recips and two screws, fully redundant (one screw, one recip per system) running R507. Next to the rack is a Munters air drier that handles supply air going into the room. Outside air is first dehumidified by a cooling coil fed from the rack, then it goes through a big desiccant wheel and down to the room. Dew point (frost point?) of this dry air last I saw was -86°C (indicator on the wall. No idea how accurate this was). Originally there was no air drier and they piped nitrogen into the room to keep it dry, so there's also a bunch of O2 sensors in there, but they were unreliable, so the air drier was installed...

One of the coolest systems I ever worked on. Back when I was dangerous. (nowhere near enough experience to be playing with such systems...)

[MikeySq]

What I do think that you might have a problem with could be oil return.

I'm thinking that a lill too also to think about Where is the Heat load from? is it only heat loss through panels?
what is the td between the last freezer and the second last freezer?
is the final freezer completly inside the second last freezer or is it only connected on the door wall?
I'm thinking this would require a VFD compressor possibly if 100% run time is required to make constant SST?

Intresting application!
sounds cheap! haha

Mike

[koolkahuna]

We have quite a few different types of freezers at a cutting edge hospital I work at. Out lab has the -80C freezers, the CVOR unit keeps some of their stuff at -313F. The MRI low stage (recycled liquid helium) keeps the superconductors of the MRI at absolute zero (I love the whole superconductor theory). Our MEG also uses liquid helium but it does not recycle it, only vents it (manufacturer says it will void the warranty to put a helium recycle unit on it, weird I know). I am the resident HVACR expert at our facility (that just means I have a lot to learn about a lot of things) so I get to work on a lot of stuff.

Yeah, our MRI was set up to vent its' entire $30,000 helium charge in the event of an emergency. If any ferrous metal was brought into the room it could be a life threatening disaster. The magnet operator would hit a large "Panic" button and by releasing the helium and the addition of heat, the magnet would be quenched.
I've heard of cops pistols, steel stretchers and a steel oxygen cylinder going horizontally airborne until they hit the machine...or whoever is in the way.
The pistol could not be used again and the oxy cylinder caused a fatality.

Before getting an MRI, a questionnaire is mandatory to redflag patients of certain professions. One of these are railway workers as from years of hammering in railspikes, small chips and fragments of iron would break off and shoot into their legs.
If not pulled out these fragments would heal over and only be discovered on x-rays or entering an MRI magnetic field which was very painful as the iron would actually cut a hole through the skin on its' way to the magnet.
Not to hijack the thread but maybe save someone some grief by knowing what to lookout for.

[jdwendling]

Even worse if you have metal fragments in your eyes. Easily happens to tradesmen even wearing glasses. Many MRI's require a trip to the eye doctor for testing first. Be Safe.