[vipluka]

Myself & Carmen Sandiago are sitting here and pondering Freezer temperatures. Myself & weirdgran have an upright freezer & sometimes it partially freezes 40% alc/vol gin in a sort of lump swimming in a thick liquid. I always thought that this was due to someone messing with the bottle. However, at CS's encouragement I've put a K thermocouple in the freezer & it is currently reading -20 deg C. It's the sort of freezer that you can't change the temp on. Is this accurate? should that sort of mix (Alc + water Freeze a this temp?) or is this meter & thermocouple reading on the dodgy side of accurate?

[qd0vhq4f]

Now at - 24.60 but slowing down.

[Qdkczrdi]

Tip the lot into a funnel and discard the ice lump. Your 40% alc/vol will now be much higher.

Home brewers call this freeze distillation or freeze concentration.

[GrolmangHat27]

Now at - 24.60 but slowing down.

Well that buggers the salt experiment then.

Well, sorta. But a 23.3 percent salt solution should be completely solid at that temperature. If you shake it a bit.

[Audi_z]

Got any boiled linseed oil in the shed? That should just freeze at about that temperature. -23.9C

Raw linseed oil should be well frozen by then. -19C

[michael247]

> at CS's encouragement I've put a K thermocouple in the freezer

I did that once. Checking it with a hand-held pyrometer. The thermocouple measurement was good to the accuracy I needed (within a few degrees) but the pyrometer measurement was way out.

> should that sort of mix (Alc + water Freeze a this temp?)



According to the above figure, an ethanol-water mixture freezes at -20 degrees C if the ethanol molality is about 9. At -25 degrees C if the ethanol molality is about 12.

Anyone know how to convert 40% alc/vol to molality?
Molality is mass of solute (ethanol) / mass of solvent (water).

[JeorgeNoxeref]

The nearest standard for themometer calibration is carbon tetrachloride. -22.9C. In the old days you would have been able to grab some from the laundry cupboard.

[c6vkuNRg]

It's now reading at minus32 Deg C. I've got a feeling that the thermo couple & meter are reading a bit more than 2 % out of range.

[Meerenuch]

Perhaps you need a cold junction reference?

Just dragging that up from memory rather than experience

[GrottereewNus]

Indeed I think you're correct, Morrie.

I may have not provided the right base information first. Infact I haven't provided a base figure for the thermocouple at room temp.

Myself & CS just decided to stick one into the freezer without testing ambient temp first... Not a good call.

Stay tuned for a more accurate set of temps.

[shihoodiacarf]

Condensation on something giving you odd readings?

Adapted a freezer for thermo cycling PC boards while operating. The test range was -10 - +60deg as recalled. Prototypes so no conformal coating. Had to be careful of condensation.

[WapSaibiar]

Indeed I think you're correct, Morrie.

I may have not provided the right base information first. Infact I haven't provided a base figure for the thermocouple at room temp.

Myself & CS just decided to stick one into the freezer without testing ambient temp first... Not a good call.

Stay tuned for a more accurate set of temps.

Isn't the cold junction meant to be part of the circuit?

[ASSESTYTEAH]

Outdoor part of the digital thermometer says negative seventeen degrees Celsius in my freezer.

[Pateeffelty]

My thermometer says a normal freezer temperature should be between -16 - -18C. One way to test it is to buy some ice cream. If after a few hours that is just hard enough then everything is OK.

[Kryfamid]

Chest freezers are designed to get colder than standard fridge freezers. Minus forty for some. Nhaving said that is your temp sensor sitting on anything. The temp should be the air temp. The coldest part of the freezer (the cooling element) will be substantially colder than the freezer air temp.

[Marlboro-oroblraM]

Chest freezers for the -40 or lower mark are a specialty item though.

[adoreorerie]

Is that minus 40 degrees Fahrenheit or Celsius??? It is important to specify these thingsso we don't get it wrong.

[Dilangos]

Is that minus 40 degrees Fahrenheit or Celsius??? It is important to specify these thingsso we don't get it wrong.

[penpizdes]

Okay. Just to clarify. Leveled out at - 34.8 deg C. this measurement was taken with 'K' Thermo couple hovering in the bottom drawer with no contact as far as I could be sure... I set it up that way, but have no way of knowing 100% unless I cut a hole through the door & have a look.

The experiment was far from complete as I should have done the middle & top & ambient with some sort of verification as to accuracy. Oh well sue us... CS had worked me through a half bottle of Hendricks Gin at the time & to be frank, I was amased I got it together to find the sodding thermocouple & the right multi-meter in the shed at that time of night anyway.

I'll try & do it better next time.

;-)

[johnsonjunior]

Okay. Just to clarify. Leveled out at - 34.8 deg C. this measurement was taken with 'K' Thermo couple hovering in the bottom drawer with no contact as far as I could be sure... I set it up that way, but have no way of knowing 100% unless I cut a hole through the door & have a look.
-------------
What you need is a cat, a schrodinger cat to be precise, but I am happy if you use any sort of cat. To be thorough you should repeat the test mutiple times with a new cat each time.