Is 15 minutes to quick to thaw during static calibration

[jabram]

I devised a static cal method to reach 50C even 60C fairly easily, I wonder if it is too quick, do I need to slow it down ?

I can monitor freezing and thawing temps, I can freeze to -17C in about 1.5 hours and it thaws out in the horizontal position in about 15 minutes to reach over 50C, vertical will take longer [I think].

I was struggling to reach 50C using a zip lock bag I could only get to 43C, I was seeing strange bumps in the curves, I guess they are caused by the plastic food container lid or the zip lock bag moving around and I may have had condensation droplets, yes I did use desiccant.

I decided to use a small glass ashtray, I taped a temperature probe inside, dried it out using a hair drier, dried the desiccant , wrapped the ashtray with cling wrap and secured it with 2 cable ties to reach all the way around.



To heat it during the thaw, I place the ashtray on top of a plastic container filled with freshly boiled water, the container holding the hot water sits in another ashtray with 2 layers of soft cloth underneath.

[jabram]

The vertical thaw is much slower, I had to wrap the whole structure in cloth to keep the heat in, takes about 1.5 hours to reach 50C, so I will slow the horizontal down by having an air gap above the hot water container [not wrapped in cloth] so that all 3 have about the same time span of 1.5 hours.

Doing it this way is resulting in much cleaner curves for me, the advantage is I only wrap it once can take all care to make sure it is dry to start with, no fiddling before removing from freezer and I can do all 3 without having to worry about condensation, only condensation I have seen is outside the container.

[bn999]

15 mins will be too fast to get the data that is needed. I recommend an hour minimum.

[jabram]

Thanks Bill, I suspected an hour or more would be required.

Using the glass ashtray with foam on both sides of the board with desiccant then a layer of cling wrap secured by cable ties gives beautiful clean curves, best so far by a long shot. Also no fiddling getting it out of the freezer.

Found that when doing vertical cal it doesn't get hot enough in the open as per my photos above, I placed the hot water container [hot water bottle would also work] in a small tall cardboard box, wrapped my small ashtray with AQ6 in 2 layers of cloth, placed that on top of hot water container, put cloth on top to seal the box, placed box on a pillow, result is clean curves, both horizontal and vertical take roughly 1.5 hours.

My earlier attempts with the food container, zip lock bag etc would only reach just over 40C, and the curves had lots of noise, now I can reach 60C, only aiming to do 50C, by the way the uSD card I am using a Team microsdhc 16GB class 10 had no problems even at 60C.


Joe