USA Cal Club: Round 2

[Andreas]

Hello,

the question is: what harms more cold or hot?
I would go pragmatic in this case:
- put the LTZ into the freezer + in the oven
  and check the deviation against previous values

Then you would need only a temperature logger to see if these limits are maintained during transport.

If the cold phase is the problem the question is wether a phase change material
or a battery for heating adds less weight to the transport.

with best regards

Andreas

[CatalinaWOW]

None of the questions can be answered meaningfully without a temperature profile.  The integrated heat flow above the desired high temperature determines the energy which must be absorbed in the combination of thermal mass and phase change.  The integrated heat flow below the minimum desired temperature is similar, but there is an option to use a battery to story energy instead of phase change material.    The following clip from an article suggests the nature of the problem.

The effect of temperature exposure during shipment on a commercially available demineralized bone matrix putty
Authors
Authors and affiliations
Mark SchallenbergerHelena LovickJalane LockeTodd MeyerGregory JudaEmail author
1.
2.
Open AccessArticle
First Online: 25 August 2016
714
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Abstract
During August and September of 2013, temperature data loggers were shipped to and from an AATB accredited and FDA registered allograft tissue processing facility in Belgrade, MT (Bacterin International, Inc.) to five warm climate cities (Dallas, TX, El Paso, TX, New Orleans, LA, Phoenix, AZ, and Tampa, FL). Shipping data acquired from 72 independent shipments were analyzed to generate an assessment of temperature exposure, shipment times, and shipping event durations experienced during routine distribution. Overall the packages experienced an average temperature of 26.2 ± 2.3 °C which mirrored the average external ambient temperature of 25.8 ± 3.0 °C. However, temperature spikes above 40 °C were frequently observed. The data from the model shipments were extrapolated to provide a worst-case high temperature spike of 52.9 °C for 12 h and 14 min. Multiple lots of a commercially available demineralized bone matrix (DBM) putty (OsteoSelect® DBM Putty) were subjected to continuous heating at 50 °C, to multiple worst-case temperature spikes, and to multiple freeze–thaw cycles to assess the effects of these temperature extremes on the handling and osteoinductivity of the allograft tissue. Five weeks of continuous exposure to 50 °C and 12 simulated worst-case one-way shipments did not adversely affect the handling characteristics or the in vivo osteoinductivity of the product.

The attached graph from the same article gives at least a first guess at what to expect.

[CatalinaWOW]

Another source of bounding information for this problem is Mil-Hdbk-310 (Widely available on line).  It is a compendium of worst case environmental data world wide, and definitions of diurnal temperature cycles for a variety of locations and probability of occurrences.  May or may not relate to conditions observed during the shipping cycle, but at least provides some basis for evaluating proposed solutions.  At any rate it is one stop shopping for a lot of geeky weather data, with references to chase down even more detail.

[TiN]

the question is: what harms more cold or hot?
I would go pragmatic in this case:
- put the LTZ into the freezer + in the oven
  and check the deviation against previous values

I don't like uncontrolled freezing, so I set my TECbox (have two LTZ-based refs right now) to +10.000C and programmed slow excursion to +20C and back to +10C.
Will see how it goes . Right now reference value is +9.9999848V at +10.000 (+/-5mC) after overnight soak.

[Vgkid]

Well a little white box arrived today , it is currently hooked up to my 10v precision supply. My precision 50v supply is currently occupied(it has been for over a year... supplying 12v to an ocxo) I can easily swap to that though.
Looks like it survived shipping alright.

[Vgkid]

I ran  some test after leaving  the 2 HP meters , and the lambda power supply powered up for a day. The Vpsu is set to 10v(9.999(8/9)X) There is no gpib , so I relied on the meters internal stat functions(the 34401A is disappointing in that regard) the ac has been off , so 12C DeltaT. using the dual Pomona banana connector( they are a tight fit on the 3456) , with TiN's safety banana plug interface(cat5 wire + Q-Tips) .
Onto the measurements:
34401A:
Min- 7.045648 , Max - 7.045690 , most readings were 7.0456(6/7)
3456A:
Min - 7.04562 , Max - 7.04566 , Mean - 7.04564 ,
Variance - 0.062449E^-9 , std dev - 7.9025uV , count 63.264K readings.
Next I will power down the 34401A , turn on the AC(hopefully more stable temperatures will follow , and hook the ltz up to the pls50 set to 12v.

[kj7e]

Appears your 3456A is slightly more stable vs the 34401A in your environment.

[Vgkid]

Ran it at 12v , with the doors open to the hallway
Min- 7.04561 , max-7.04563 , mean- 7.04562 , var-0.0251 , 5uV std dev.
So a bit more stable.
Other than switching psu's it hasn't changed any. Even going from 10v>>12v yielded no voltage shifts.

[Vgkid]

Looking into using the ratio mode with my 3456A , I fired up my mv106, I set the knobs to read the same as the ltz output , and the ratio was rather far off(1.003xxx). To get it reading as close to one took getting my mv106a far from its equal set point :?

[cellularmitosis]

You could also set the MV106 equal and then measure the difference between them.  Connect the negative outputs together and connect both positives to the meter.

[FriedLogic]

the question is: what harms more cold or hot?
I would go pragmatic in this case:
- put the LTZ into the freezer + in the oven
  and check the deviation against previous values

Hi,

It might also be about how often it sees a particular temperature, rather than just whether it's high or low. Testing for that (unless there is already data on it available somewhere) would likely be a long term thing.

Deliberately subjecting them to a wider range of temperatures is not ideal, but it may still be a good option if you don't want to have to always send them in a box the size of a fridge.

There's still the problem of what to do to minimize issues like hysteresis when you fire them up again, but assuming that it's just the LTZ that you need to work on, adjusting its temperature should not make the whole box much bigger than it would need to be otherwise.

[hwj-d]

I've ordered this Mini Templogger:
https://shop.insidegadgets.com/product/mini-temp-logger/

But it's from Australia, so it might take some time.

In the moment I'm in contact with ap from ab-precision to calibrate some of my ltz1000 (within the possible). After that, I could send it to the USA-Cal-Club for going around and free disposal there as a second item, if cellular or an other member want to manage that too.

But for now, it's only an idea, for a second item. An other one of these could circle around in Europe.

Please tell me, what you think about it.

[cellularmitosis]

Ran it at 12v , with the doors open to the hallway
Min- 7.04561 , max-7.04563 , mean- 7.04562 , var-0.0251 , 5uV std dev.
So a bit more stable.
Other than switching psu's it hasn't changed any. Even going from 10v>>12v yielded no voltage shifts.

Hey Vgkid, any update?

[Vgkid]

Ran it at 12v , with the doors open to the hallway
Min- 7.04561 , max-7.04563 , mean- 7.04562 , var-0.0251 , 5uV std dev.
So a bit more stable.
Other than switching psu's it hasn't changed any. Even going from 10v>>12v yielded no voltage shifts.

Hey Vgkid, any update?

Not yet , haven't had any free time at home.  
I will be running it against the mv106 using the 3456a as a null meter (actually a few mv of offset, unless anyone has a different idea) in a few days. Then I will ship it out.
I have yet to power it down for more than 10 minutes.

[Vgkid]

Just powered up the mv106, so I can run the null test shortly.
Did another stability test similiar to the last, except the results are better .
Min:7.04563, max:7.04564 , avg:7.04563 , 59968 readings , 0.007233e^-9 var , 2.69uV std deviation.

[Vgkid]

Ran it against the mv-106 as a null, with a constant offset. Lets just say that this was extremely sensitive to anything... Makes me really want to repurpose my L&N linear amp.
min(-100.0142)max(-99.99937)avg(-100.0064)var(0.016487)stddev(4.06uV, still not bad)
will run another test before shipping out either Tuesday, or Weds.
As an aside anyone want to buy some vhp4(1r , unknown tolerance) resistors

[Vgkid]

I will ship out tomorrow, last weeks tropical storm delayed it a week.
Last call on the resistors.

[Vgkid]

I dropped it off at the post office a few minutes ago.

[Vgkid]

@ CellularMitosis , has the ltz1000 box arrived yet , if not , it shouldn't be too much longer.
In other news , my box-o-resistors came today.

[bitseeker]

Interesting. I didn't know resistors came in that packaging. At first, I thought they were transistors. Do people mount them to heat sinks or something?

[Vgkid]

Interesting. I didn't know resistors came in that packaging. At first, I thought they were transistors. Do people mount them to heat sinks or something?

Correct , they are precision 10W (max heatsunk) or 3w in air resistors. They are 1 Ohm/.1% vhp-4 resistors

[bitseeker]

Ah, yes. Makes sense. I'm just used to seeing the wire wound power resistors with fins.

[cellularmitosis]

@ CellularMitosis , has the ltz1000 box arrived yet , if not , it shouldn't be too much longer.
In other news , my box-o-resistors came today.

Not yet, hopefully tomorrow! 

[cellularmitosis]

Heyo!

The ref arrived last night and I had it running today.  Surprisingly, it looks like it has drifted up by a few microvolts since last month:

https://www.eevblog.com/forum/metrology/usa-cal-club-round-2/msg1516537/#msg1516537

I know I said I would follow a random participant order, but I'm going to violate that rule and send it off to kj7e next, to take advantage of his recent calibration 

I need to get a few more of these into rotation!  We've got a lot of participants this time

[bitseeker]

I know I said I would follow a random participant order, but I'm going to violate that rule and send it off to kj7e next, to take advantage of his recent calibration 

Well, that sounds like a good exception to the rule.