Jump to content

Shipping/heatpack Temp Data


Recommended Posts

Just in case anyone is interested and finds this information useful, I'm sharing some data I captured on heat packs.

The use of heatpacks and how well they worked was a big question I had when I first started breeding/shipping fish.  How many? How big of a box? What kind of heat pack (40hr, 72hr)?

To find the answers to these questions I've been capturing temp data at different times of the year, in different sized boxes, etc.

I figured I'd share the most recent of these here just in case anyone ever had the same questions. 

Hope someone finds this useful

  • Box Size: 12"x9"x6" (648 cubic inches volume)
  • Number of heat packs used: 2
  • Heat pack type: Uniheat 72hr
  • I moved this box inside and outside a number of times during this capture. When it was not inside, it was left outside, on my porch, in the sun. 
  • The weather was a typical NJ spring day. Highs in the 70s, lows in the 40s.
  • One data logger was kept outside the box; the other was inside.
  • The logger inside the box was near the bottom and the heat packs taped to the lid.
  • The box contained 2 bags with about 12 or so ounces of water in each. The empty space inside the box was packed with crumbled newsprint. 
  • The box was insulated on all sides with 1" styro.

Outside box graph and data:




Inside box graph and data:


  • Thanks 1
  • Love 1
Link to comment
Share on other sites

  • Administrators

Nice, when I was doing testing, we found oxygen can be limiting for the reaction of heat. We also sent packages around the USA to try and estimate how often packages sad in heated buildings vs outside, vs in the back of a truck etc. Was time consuming and really proved that it's hard to predict what will happen after it leaves our facility. I was on a flight last night, in Atlanta it was 80 degrees with a heat pack, but then when I landed in PA it was 45 degrees. Making it difficult to predict the right amount of heat packs and the path it will take due to flight availability.

Now we use the feedback from customers that we track due to reships to adjust our algorithm to try and best predict. Big service disruptions from natural disasters can still throw in a monkey wrench, but each year our algorithm has gotten more efficient. I think temp logging in regards to fish and plants hasn't been tested as much as we think as it's such a hard thing to perfect.

Link to comment
Share on other sites


On 4/19/2023 at 1:54 PM, Cory said:

Now we use the feedback from customers that we track due to reships to adjust our algorithm to try and best predict.

I do the same, minus an algorithm to tweak. When something goes wrong I try to get what feedback I can from the customer and them spend some time looking at the carrier's path to see what route a package took and what the conditions were like at each stop-over. 

My main concern for this recent test was how high would 2 heatpacks go in a box sitting at room temp. I don't think these hit peak temperature while inside my house, but I'm going to say that in my use cases (that is, how I pack and stuff boxes), two heatpacks will go about 20F above the outside temp, which is what I suspected based on what information I've seen regarding Uniheat packs. This is the second time I've done this specific test.

I've also sent some packages around the country with data loggers in them and learned about the same as you. It is variable and hard to predict. For instance I sent a box to Louisiana the other week and, from the carrier's tracking data, the shipment looked like it was in a truck driving around NJ and NY state for two days, from facility to facility, before being put on a plane and arriving late to the customer. It was cold that week, so the you can guess how well the fish fared . . . 

In my experience, the above is an outlier, but it does happen from time to time, and like you said, that does get hard to plan for. Had I packed the Louisiana shipment with 2 heatpacks, when the package reached the destination I'd probably have overheated the contents rather than froze them.  

On a side note, the one thing my anecdotal data has taught me is that anything that stays too long at the UPS hub in Dallas in the middle summer ain't gonna make it. I don't know if they have poor climate control there, or just let things sit on trucks outside for a long time. When I see a package routed through there, my heart sinks and I hope for the best. 

Anyway, thanks for taking the time to also share your experience with this!

Edited by tolstoy21
  • Love 1
Link to comment
Share on other sites

  • Administrators

Also we found out that different heat pack lengths. So 60 hour vs 72 hour vs 96 hours have different heat levels and profiles. So We are mostly switching to 96 inch heat packs as we like their heat profile better. Where a shorter say 48 inch heat pack goes from cold to really hot and cold again quickly. Something to possibly test.

To simulate some trips, we use the freezer, fridge, fish room, warehouse, outside etc. There are other variables like, a package on a rack in the back of the truck is very different from right over the rear axle hub that gets super hot.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Create New...