heat packs and oxygen

[Ice Cold Milk]

Ultimately if your concerned for the spider, simply ship in its own 'diving bell' - a sealed deli cup or vial with it's own private O2 supply...
Tony

This is a very practical solution, since t's can survive for MUCH longer than most people think in an airtight container. (certainly longer than what it takes for any parcel service to deliver from state to state).

-=ICM=-

 

[UrbanJungles]

I have gotten boxes (well sealed) with COLD 40 hour packs. Left out these packs warm up again to an extent, so ....Was there too little oxygen in the box?
Tony

Most likely just crappy or re-used heat packs.

 

[Tony]

Most likely just crappy or re-used heat packs.

Unlikely...In one case for sure I sent them some packs that I bought from Superior......

 

[kbekker]

Although extremely artificial, it might be worth mentioning. After a couple of comments posted above I wondered can this effect even be witnessed? I placed a 70g, 24hr heat pack in a sealed 2liter container (plastic bag), with 7 crickets. The hand warmer had already been used in a shipment so it was probably not at peak performance. The crickets ran out of oxygen within 2hrs (they appeared dead but resumed motion after the bag was opened.).

Yes I know shipment containers are not sealed…. However I don’t think a tightly fitting Styrofoam box allows for much air exchange and I have had small packages that arrived with almost all of the sides covered in plastic tape.

Yes, it does suck in oxygen. Selectively, no less. If the box really was sealed, the atmospheric pressure would drop. Quickly.


Fact is, this could, in reality, be a problem...

The bag did appear to loose pressure also

This is a very practical solution, since t's can survive for MUCH longer than most people think in an airtight container. (certainly longer than what it takes for any parcel service to deliver from state to state).

-=ICM=-

On small well sealed shipments this may be a good idea

 

[DrAce]

Overall how much difference in Volume will there be once the heat pack is 'consumed'? That answer will help determine if any 'sucking' is going to take place.... If it consumes oxygen and replaces it with some other gas, well we will have convection inside the box but very little 'draw' from the outside.
I have gotten boxes (well sealed) with COLD 40 hour packs. Left out these packs warm up again to an extent, so ....Was there too little oxygen in the box?
...

No, what happened is that you moved the warmer. There's a gradient of reacted and unreacted stuff in the warmer. If you move it about a bit, unreacted iron starts getting oxygen, then it'll come back to life for a bit.

Although extremely artificial, it might be worth mentioning. After a couple of comments posted above I wondered can this effect even be witnessed? I placed a 70g, 24hr heat pack in a sealed 2liter container (plastic bag), with 7 crickets. The hand warmer had already been used in a shipment so it was probably not at peak performance. The crickets ran out of oxygen within 2hrs (they appeared dead but resumed motion after the bag was opened.).
...
The bag did appear to loose pressure also
...

Told you!

Seriously, though, I doubt this is a problem unless you are placing the tarantula in a completely sealed vessel with the warmer. Fact is, the reaction takes a while - that's why it's useful. So there is no sudden vacuum produced. As long as there is some diffusion of air into the container, the tarantula will be fine.

 

[JDeRosa]

I ship with big 72 hour heat packs and my T's arrive fine.

 

[gvfarns]

Although extremely artificial, it might be worth mentioning. After a couple of comments posted above I wondered can this effect even be witnessed? I placed a 70g, 24hr heat pack in a sealed 2liter container (plastic bag), with 7 crickets. The hand warmer had already been used in a shipment so it was probably not at peak performance. The crickets ran out of oxygen within 2hrs (they appeared dead but resumed motion after the bag was opened.).

Wow that's pretty significant information. If in two hours the heat pack consumed enough oxygen that the crickets passed out, I'd definitely say there's a concern about oxygen in a shipped box.

It's true that tarantulas--and crickets--can survive for a long time without air, but let's set that first order concern aside for a second and consider the other issue. If the heat pack consumes enough oxygen that it made the difference that was suggested above within 2 hours, then it seems likely that it could consume most of the oxygen in the box and then the reaction will slow down and the heat pack will cease to do its job well.

Sure we all know that most inverts shipped in the winter do just fine, but how do we know that the heat packs are actually doing their job, rather than it just not being a big problem because most post offices, delivery vehicles, etc are warm enough that the T's don't freeze in that time?

I guess for now we just have to go with what's working well enough.

 

[kbekker]

but as I even pointed out...most boxes are not sealed.

 

[gvfarns]

but as I even pointed out...most boxes are not sealed.

People keep pointing this out, but they don't have to be perfectly sealed for what I said to be true. Cardboard doesn't exactly allow a lot of oxygen diffusion through the main surface, and then you close it up completely and put packing tape around the edges. If you put a mammal in such a box it would asphyxiate rather quickly, even without a heat pack. I don't see why everyone states without consideration that shipped boxes allow a lot of air in. Enough for a T? Yes for sure. Enough for a heat pack? That's not clear to me. I certainly don't think it should be taken as given.

 

[barabootom]

Although extremely artificial, it might be worth mentioning. After a couple of comments posted above I wondered can this effect even be witnessed? I placed a 70g, 24hr heat pack in a sealed 2liter container (plastic bag), with 7 crickets. The hand warmer had already been used in a shipment so it was probably not at peak performance. The crickets ran out of oxygen within 2hrs (they appeared dead but resumed motion after the bag was opened.).

Was the hand warmer the type made for shipping animals and fish, or was it a hand warmer for keeping warm while hunting and ice fishing? The latter gets much hotter and I'm sure uses more oxygen.

Regardless, as mentioned by someone previously, I think the wisest choice is use a heat pack with the T's sealed in a diving bell type enclosure. That way the T will have plenty of air as long as the enclosure isn't too small.

When you removed the crickets was the warmer still warm, or had it stopped heating? Did it warm up again after being removed from the bag? Was the plastic bag you used a new bag or had it been used for something else previously? I think someone should investigate this a little further.

 

[Nerri1029]

OK ..

IF the air in that 2L bag cooled at all a decrease in volume will also be observed. Charles' Law.

But if O2 if truly being consumed as rates like Dr Ace explained using Stoichiometry ( I love saying that word ) - just fancy name for recipe calculations for Chemistry.

then the volume of gases in the bag would decrease as well.

I have O2 sensors and I can actually run this experiment.

I'll keep you posted.

 

[gvfarns]

Was the hand warmer the type made for shipping animals and fish, or was it a hand warmer for keeping warm while hunting and ice fishing? The latter gets much hotter and I'm sure uses more oxygen.

Regardless, as mentioned by someone previously, I think the wisest choice is use a heat pack with the T's sealed in a diving bell type enclosure. That way the T will have plenty of air as long as the enclosure isn't too small.

When you removed the crickets was the warmer still warm, or had it stopped heating? Did it warm up again after being removed from the bag? Was the plastic bag you used a new bag or had it been used for something else previously? I think someone should investigate this a little further.

Yeah, I'd also like to see someone directly test this by putting a warmer in a box with some crix, sealing it up real well, and then checking on them the next day to see if they have passed out.

 

[kbekker]

Was the hand warmer the type made for shipping animals and fish, or was it a hand warmer for keeping warm while hunting and ice fishing? The latter gets much hotter and I'm sure uses more oxygen.

Regardless, as mentioned by someone previously, I think the wisest choice is use a heat pack with the T's sealed in a diving bell type enclosure. That way the T will have plenty of air as long as the enclosure isn't too small.

When you removed the crickets was the warmer still warm, or had it stopped heating? Did it warm up again after being removed from the bag? Was the plastic bag you used a new bag or had it been used for something else previously? I think someone should investigate this a little further.

The hand warmer was left over from a cricket shipment, but it was not specifically designed for shipping animals. The bag was new. I did not pay attention to the warmer afterwards, mostly because I have done the deprive a hand warmer of oxygen and then expose it to oxygen again trick, they stop working and then start again.

 

[skips]

Nerri, i'm really excited to see what your experiment comes up with. I did pretty much the same thing as DrAce but in a different way. I assumed 20g iron, a ten gallon container, and a packing temp of 70 degrees Fahrenheit. Used the ideal gas law and found how many moles of gas would be in the package, took the percent of oxygen in average air and how much oxygen would be used with 20g iron. It ended up I got ~.329 moles of O2 before and would be left with .061 moles. meaning after the reaction you'd only have 18.5% oxygen left. The ideal gas law is fairly inacurate, but that's a big difference if my logic is sound, DrAce?

 

[skips]

You might do better using sodium acetate warmers as the heat comes from the sodium acetate coming out of solution and has nothing to do with reactants such as oxygen. I think they get pretty hot though and may not last as long. I havnt used them.

 

[Olan]

I have now shipped twice with heat packs, both in styrofoam containers taped shut (which I assume means the're airtight). Both took two days to arrive and both were fine. I may from now on tightly seal the deli container to make a diving bell just to be safe.

-Olan

 

[Nerri1029]

You might do better using sodium acetate warmers as the heat comes from the sodium acetate coming out of solution and has nothing to do with reactants such as oxygen. I think they get pretty hot though and may not last as long. I havnt used them.

I have used these.. they get very hot at first and do not last more than 1-2 hrs.

 

[MizM]

That's a really good observation! Usually we just don't worry about oxygen for the T's. Maybe that's the cause of some of these mysterious deaths we see in winter shipping.

I agree! How many times have we seen Ts that were shipped out healthy arrive in a pristine, unmolested box only to find them dead for no apparent reason? It definitely could be a contributing factor, especially since no one has thought of it before.

We know Ts consume little oxygen, but we don't know exactly how much.

This is exactly the kind of question that leads to experimentation and education. Something we need more of in the hobby!!

 

[DrAce]

Nerri, i'm really excited to see what your experiment comes up with. I did pretty much the same thing as DrAce but in a different way. I assumed 20g iron, a ten gallon container, and a packing temp of 70 degrees Fahrenheit. Used the ideal gas law and found how many moles of gas would be in the package, took the percent of oxygen in average air and how much oxygen would be used with 20g iron. It ended up I got ~.329 moles of O2 before and would be left with .061 moles. meaning after the reaction you'd only have 18.5% oxygen left. The ideal gas law is fairly inacurate, but that's a big difference if my logic is sound, DrAce?

Well.. the ideal gas law is actually pretty good if you are dealing with only one gas. It's terrible if reactions can happen and the like.

Even then, it's a pretty good estimate of what you would expect to happen.

Note, of course, that you are ONLY removing oxygen from the sample... not anything else. So the oxygen left is 18.5% of what you started with. The amount of total gas is MUCH higher than that... since air is mostly nitrogen.

 

[skips]

Well.. the ideal gas law is actually pretty good if you are dealing with only one gas. It's terrible if reactions can happen and the like.

Even then, it's a pretty good estimate of what you would expect to happen.

Note, of course, that you are ONLY removing oxygen from the sample... not anything else. So the oxygen left is 18.5% of what you started with. The amount of total gas is MUCH higher than that... since air is mostly nitrogen.

Right. I did figure that in the fact that oxygen is only 21% of the gas in the box. If that all works though people must really be telling the truth when they say that T's don't breath much. I think any kind of vertebrate would die. But I have to think that there's a significant margin of error in the calculation. it's not like you have pristine condiition in which to carry out the experiment.