# A better gel for shipping...TESTED!



## Dancing frogs (Feb 20, 2004)

Anyone who has read my rants promoting the use of gel-packs in frog shipments knows how much I recommend them.
I wonder if this would be much better?

http://www.tcpreliable.com/products/pcm/phase22.html

I didn't get good enough math grades to consider trying physics, so if someone has the knowledge, would they care to explain the phase change process as it would pertain to our usage?

This company has a few different gels, all with different phase change points, obviously for different uses.
I have no idea the cost of these, but wonder how much better (if they are) than the generic gels that are more common.

Anyone care to take a stab?


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## defaced (May 23, 2005)

Here's my guess:

When a substance changes phases, there is an isothermal reaction that takes place for an extended period of time. This is associated with the energy the substance is taking in, or releasing. If you engineer a substance to have a very long, isothermal phase change, it would be incredibly thermally stable. 

There is one hitch, nature likes energy to be at its lowest state. To satisfy this in our application, you would heat this thing up, it would take in energy during this time and if enough heat were supplied, the phase change would take place. Now when you remove the heat, it will be begin to cool at some rate. When it reaches the temperature of the phase change, it will stay there for an extended period of time (this neglects undercooling whis is usually pretty subtle). Once the phase change is over, it will continue to cool. 

Below is a graph for the heating of ice to steam. As you can see, there are two isothermal regions, one when ice goes to water, and another when water goes to steam. If you reversed this graph (put the right side of the left and the left side on the right), you would have the time/temperature graph of water cooling from steam to ice. 










So basically, these things are most stable at their phase temperature. 

And even if my guess is wrong, if I did a good job, you should understand the concept of latent heat.


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## pl259 (Feb 27, 2006)

Phase change materials that change at room temperature would certainly be the holy grail of packaging materials. Not sure of the cost though. I used a paraffin based PCMs in an electronics sensor several years ago. The thermal energy from the electronics was absorbed by the wax as it melted, keeping the electronics cool. Afterwards it would revert to it's solid state, ready for the next turn on. 

That Phase22 product looks interesting because it's reusable and disposible which means we might be able to find a bio testing company that throws them out.

Here's another one...

http://www.saftpak.com/catalog/CatalogPages12-13.pdf

I'll try to get some samples for testing.

Edit...It looks like the Saf-T-Paks are $6-$7 a piece.


EricG.NH


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## Dancing frogs (Feb 20, 2004)

I got a quote of $3.60 per panel or $129.00 for a case of 36, for a 5x5x1" rigid panel of the phase 22.
Or roughly 4 times the price of the ones I use now, and due to the fact that they are non-flexable, wouldn't be as easy to pack with. Unless I went with new shipping boxes that would allow that size to fit.
At this point, I don't think it would be worth it, with shipping costs already getting out of hand.
Though I think I will try to get two packs to test...who knows, maybee these things are the cat's meow?


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## defaced (May 23, 2005)

I think it'd be nice to see if there is a difference with our application. If so, I think it'd be a good opt-in thing for a buyer to consider paying extra for when weather is not favorable.


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## Dancing frogs (Feb 20, 2004)

I'm thinking a returnable deposit for heavyduty packaging, or if selling to a repeat customer or someone you know you can trust, don't add the cost, and simply ask them to return the packaging via the cheapest method possible.
I've done that before...packaging doesn't grow on trees!


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## defaced (May 23, 2005)

I'm doing that with my tanks. 25 dollar deposit on the plywood box and I pay for return shipping. We'll see how it goes.


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## pl259 (Feb 27, 2006)

Mike and Brian,

A rep is bringing me 4 Saftpaks on Thurs for test. Let me try to get some of these Phase22 to test as well.

I think the potential of these products is huge. Yes, they're a few dollars more then heat/cold packs, but they're resusable. That's not the biggest plus. They will maintain a near constant temp inside our typical insulated shipping boxes, over a very wide range of temps, for a long period of time, likely greater than 36hrs. This not only reduces risk, but extends the shipping seasons. Additionally they may save cost by allowing us to ship using other then overnight services. Further, they don't consume O2. It would also be the same product year round.

This type of shipping solution is what I was going after in the other thread.
One that doesn't care or cares less what exterior temps the package sees. I threw out of contention vacuum panel insulators because of cost. 

EricG.NH


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## Dancing frogs (Feb 20, 2004)

Yeah, if we could do away with the chemical heat packs altogether, I'd be very happy!


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## Catfur (Oct 5, 2004)

A phase change material at 71 F (which is what these are) is nearly perfect for PDF shipping. As long as you start out the package on the right side of the phase change (over 71F in winter, under in the summer), this ought to add significant temperature stability to the packaging. I had been wondering for a while if there was a phase change material in the 60s to mid 70s range. Now, where do you buy these?


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## Dancing frogs (Feb 20, 2004)

Well, I got the quote like I mentioned, "$3.60 per panel or $129.00 for a case of 36, for a 5x5x1" rigid panel of the phase 22."
And since the material is 4 times the price what I use now, I asked if I could buy 6 for testing and was told I have to buy by the case.
If someone wants to split some, I may be up for it, I'd really like to try them out.
Pm or email me if interested, or if you want a case for you'reself, there are links to contacts, try them all till you get one to respond (I did).


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## Dancing frogs (Feb 20, 2004)

Ok, I bought a case of em...

Here is a comparison of the gel packs I was using (8oz soft gel packs from superior), and the phase 22 hard panels.
Both packages were packed the same, in a homemade cooler made from R-10 stryofoam, glued together with polyurethane adhesive, with interior dimensions of 6x6x6". One pack on the bottom. stryro peanuts to keep the data logger in the middle, and another pack on top, with the top of the styrofoam box sealed with tape.
The gels and panels were "charged" similarly, by soaking in hot tap water.
Test conditions were in the freezer, with a temp range of +10F to -3F (sorry, no chart available)
Here is the box using the gels I had been using...








Here is the box using the phase 22...








Sorry for the other traces in there (the red one is temperature in F).

So far I like the results, but designing a package around the 5x5x1" hard pack is a pain, so I think I will drain a few into bags and seal them, to make custom "gel packs".


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## gary1218 (Dec 31, 2005)

What do the phase 22s cost?


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## pl259 (Feb 27, 2006)

Nice job Brian! Thanks for taking the time to run those. I still have my PCMs but haven't had the time to test. Work's still been crazy. 

It looks like they both started at close to 90F. Is that right?
It's also interesting the PCM dropped to 10F and the gel dropped slowly after 32F or so. Is there any special reason for this?

I guess I would believe that the area under both of those curves would have to be the same. Interesting how the PCM crashes. 

It might be an interesting test using both, one of each. There is only so much energy in the gel packs. One gives it up asymptotically, the other abruptly. Not sure which is the best way to go.

EricG.NH


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## joshsfrogs (May 6, 2004)

> It's also interesting the PCM dropped to 10F and the gel dropped slowly after 32F or so. Is there any special reason for this?


The phase change temp of the gel pack?

So at less than 10 degrees the package stayed above 50 degrees for over 12 hours!? I think when you factor in late night dropoff, pickup at the station, and the fact that your freezer is far more harsh than the temps seen in shipping...wow, these things are pretty sweet.

I wonder if we would want the phase change temp a little lower like 55 degrees. At 71 degrees, the phase change could happen soon after packaging and at the hub (68-70 degrees) and then be vulnerable during the rest of transit. Have it have a phase change below 60 would also allow it to gain more energy in transit during times of warming (i.e. loose energy on the tarmac, gain it in the 60 degree cargo compartment, etc.)


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## Dancing frogs (Feb 20, 2004)

Yeah, 
I ought to try leaving the ones with the generic gels in the freezer longer, I'm guessing that their phase temp is somewhere just below the freezing point of water, therefore holding temps in that range steady longer, as thats probably what they are meant for anyway.
I also did a test with water bottles that showed the same response of stabilizing at the freezing point.

They were both charged in hot tap water, so the gel/phase change material were in the 90's at the time of packing.

I kind of had a similar, but different idea of mixing the materials, I was wondering if perhaps a pcm with a lower phase temp would hold the box in the safe range longer, to push the plummet further down the line, but I would imagine the usable time would remain similar, just stabilizing at a cooler temp.
I also think once I get the custom gel packs made (gotta go to work and use a sealer), the results will be better, due to more mass in one place, rather than just the small amounts in the small container, which doesn't effeciently use the space available in my coolers.


The price of the pcms was posted a couple posts back.


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## Dancing frogs (Feb 20, 2004)

Eric,
Can you post the dimensions of the pcm's you have?


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## pl259 (Feb 27, 2006)

Brian,
The PCMS I have are from a company called SaftPak. 

http://www.saf-t-supply.com/shopper_catalog.asp?ID=7&ShopperRegionID=

(Not the best website)

I have three each of the STP315(20-24C) and the STP317(15-30C)

They basically are a soft gel pack about 6"x9".

Your generic gels basically have a lot of mass per unit volume, read density, and therefore have a lot of heat storage capacilty. 

The PCMS are interesting in that they should also absorb and store energy without changing their temp abruptly. Using them with a heat pack is another interesting approach.

EricG.NH


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## sbreland (May 4, 2006)

Brian,
I was wondering if you did or could do a test just outside overnight in regular temps versus a freezer overnight to see how the phase 22 holds up to more realisic temps. I know we like to play at extremes, but I would be very curious how these things would perform with normal temps (in the 20-30s) overnight versus what a freezer put them through. I may not understand the concept completely, but would a warmer temperature (versus that of the freezer) not let it stay stable longer?


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## Dancing frogs (Feb 20, 2004)

Same box, packed the same way (with 2 phase 22 packs) in the fridge, 37-45F:


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## sbreland (May 4, 2006)

Now that's what I'm talking about. So basically it stayed 55 degrees until where it says Monday but stayed 45 or warmer for the entire trial. I know it says Sun-Mon, but how many hours are we talking from beginning of trial to the end on that one?


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## Dancing frogs (Feb 20, 2004)

That test was from 24, Feb, 18:37, to 26 Feb, 19:17.
So just a little over two days.


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## sbreland (May 4, 2006)

Nice, that was longer than I thought. So it looks like it held over 60 for about the first 24 hours and 70 for at least 16-18. This sounds like a dream and looks like this could be the answers to all of our shipping problems.


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## Dancing frogs (Feb 20, 2004)

Getting closer...
 
My most recent test, a 9x9x9 homemade styro cooler made of building insulation.
Used 4 homemade gels using the phase 22, each contains the contents of 2 of the hard panel pcms. 
The box can hold 3-4oz. gladware containers, weighs in at 5 lbs, and should ship priority fedex for $50
Here is the ambient test conditions:









Conditions inside box:









The spike to 86F at the beginning can be eliminated simply by waiting a little longer after preparing the pcm (hot water bath), so that they may come down to the desired temperature (this is where a temp gun really helps), as you can see, the material loses heat fairly fast above the phase change temperature.
I plan on further testing (in more realistic temps) to try to lose some of the weight, and expense of the material used.


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## Dancing frogs (Feb 20, 2004)

joshsfrogs said:


> > It's also interesting the PCM dropped to 10F and the gel dropped slowly after 32F or so. Is there any special reason for this?
> 
> 
> The phase change temp of the gel pack?
> ...


I think I missed this post, sorry Josh, and yes you are correct on the phase change point of the superior gels...I did a longer test using those gels, and with two gels in a small 1" thick styro cooler, in a 4F freezer, the temp fell fairly quick to 32F, but stabilized after that, and did not fall below 32F for 24 hours!
Yeah, a lower phase change point may make winter shipments more weight effecient (compared to using more phase22), however, the PCM's work both ways...once they get cold beyond their phase point, though temps will fall fast after that, they will also come back up fairly fast, until they reach phase temp, and level off again.
TCP also makes a Phase 5, which is somewhere around 40F...but again, if the temp fell low enough to get to 40, it would take alot of heat/time to get back above that temp...but would keep the contents of the box from freezing.
I am very pleased with the results of the more realistic garage tests I have done (with the phase 22) recently...have to post those one of these days...


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## Dancing frogs (Feb 20, 2004)

Here is an example of the phase change of the superior gels:









Test was performed in a single digit (4-7F) freezer. with the gels in a standard shipping cooler.

Here is a graph showing how the phase 5 responds in the freezer. Data logger was surrounded by a mere 200g of the phase 5 in bags, then put in a similar cooler as above. Note how it took over 13 hours to get to freezing:









Not that 40 degrees is ideal for shipping frogs, but I think it shows how it would be beneficial to have a PCM with a lower phase change point for winter, as it would last longer with less material (like Josh was getting at).


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## Dancing frogs (Feb 20, 2004)

Just had a thought...
I wonder how butter would work?


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