Water Environment Federation (WEF) Discussion Forums / WEF Discussion Forums / Laboratory Management & Technical Issues / Maintaining Temperature less than 6C in a cool box / Latest Posts

RE: Maintaining Temperature less than 6C in a cool box

Sabir — Thu, 12 Jun 2008 01:34:29 GMT

I appreciate all inputs and am happy to say that now we have sorted this problem out. The solution really triggers with the ideas from the different posts like solar refrigerator and use of refrigerator on site. I never thought for such probability before because during sampling deep into desert refrigerators were out of question. While I was looking for some suitable options, I observed while shopping in a pharmacy shop that a sales man has delivered some vaccination and he came out from just an ordinary car (not refrigerated one) I became interested. I want to know how they are refrigerating vaccines so I asked him and he showed me a car refrigerator. Then I bought one for our lab. It is of 15L capacity (51x30x33cm), able to cool below 30-40C from ambient and can accommodate 10 to 12 sample containers easily. It can be conveniently plugged into DC 12 volts cigarette lighter in a car. Now we are using it successfully for carrying ice to the sampling site and for transportation samples back to laboratory while keeping temperature at below 6C.

RE: Maintaining Temperature less than 6C in a cool box

Sabir — Thu, 12 Jun 2008 00:32:08 GMT

We did not try dry ice but I do not think so if dry ice is recommended for storage of samples meant for Microbiological testing. Dry ice temperature is -78.5C and it will lower the temperature below freezing point that will invalidate the sample and bacteria can not tolerate this shock.

RE: Maintaining Temperature less than 6C in a cool box

Egadz — Wed, 11 Jun 2008 15:56:54 GMT

Ever think about trying dry ice? Just a thought.

Egadz

RE: Maintaining Temperature less than 6C in a cool box

MoscowLabAnalyst — Tue, 27 May 2008 14:49:41 GMT

solar powered refrigerators?

RE: Maintaining Temperature less than 6C in a cool box

Sabir — Sun, 25 May 2008 01:26:13 GMT

I appreciate all valuable suggestions and many inputs but I am still wondering if less than 6°C temperature limit is practically achievable in a coolbox under such severe outside conditions. Because we try this in many ways (it works for the cases when we cooled under refrigerator before transportation) but most of the time we have to collect and transport samples from the far away sites located deep into desert where there is no refrigerator and practically difficult to collect at night. I am going to validate sample transportation for such occasions to ensure sample integrity and I will appreciate if someone will direct me to any similar study.

RE: Maintaining Temperature less than 6C in a cool box

DesertSand — Sat, 24 May 2008 23:26:43 GMT

Sabir

We face this problem in Iraq. To work around the temps, we are cooling the samples as soon as we take them, surrounding them in ice and water. Transport with lots of ice, and transport at night, to at least avoid the hottest temperatures and to keep direct sun light effects out of the mix.

Because of our transportation problems, we lose a day of holding time to travel, but the lab has a heads up the sample is coming and they are ready to test ASAP.

Good luck.

RE: Maintaining Temperature less than 6C in a cool box

Sabir — Fri, 23 May 2008 01:57:51 GMT

Good idea, but I am not sure if this combination can be used for cooling samples. I suspect that addition of salt over ice lowers the temperature to freezing point. I remember when my grandma, years ago, prepared homemade ice cream by putting the sweetened milk in a metal container and surrounded it by consecutive layers of smashed ice and table salt (without refrigerator), believe me solidified icecream was ready with in 30min.

RE: Maintaining Temperature less than 6C in a cool box

Rick Ohalek — Thu, 22 May 2008 12:09:57 GMT

I vaguely remember watching an episode of Myth Busters where they were trying to determine the quickest way to cool down a warm beer. If I recall correctly, the quickest method was a mixture of ice, water and salt. Seems like this could apply to sample cooling as well as cooling your favorite beverage.

RE: Maintaining Temperature less than 6C in a cool box

Old lag — Tue, 13 May 2008 16:36:55 GMT

The secret is to get the samples cold before you ship them. Ice is better than cool packs because you can surround the samples. Ice the samples after taking them and then change the ice before you ship them -- should be OK. Better yet if you can refrigerate them for several hours before you ship. They will stay cold.

RE: Maintaining Temperature less than 6C in a cool box

MoscowLabAnalyst — Tue, 13 May 2008 11:19:33 GMT

Finally, a chance to use all those thermodynamic courses....

The answer is... it depends.

It depends on the mass of ice, the ambient temperature, the possibility for convection (is a warm wind blowing?), radiation (is the sun shining directly on the sampler?), conduction (is the sampler well insulated?) and a host of other parameters. You could research this one to death, do all the calculations, and still not really know for sure until you try. And every day the results could be a little different...

In Idaho, we had outdoor samplers, with ice in the bottom, sampling during ambient temperatures over 90F and taking warm sewage samples. The samplers were suspended in sewer accesses (i.e. down in a tunnel in the shade with no wind and reasonably good insulation). There was still ice at the end of 24 hours.

YMMV (Your Mileage May Vary) but it's certainly worth a try.

MLA

Maintaining Temperature less than 6C in a cool box

Sabir — Tue, 13 May 2008 04:03:59 GMT

one of our laboratory located in Middle East region (where outside temperature usually reached above 45C) is facing problem to maintain the preservation temperature limits of less than 6C in a cool box during transportation of the samples. I am wondering if this temperature limit is practically achievable in a coolbox containing ice or ice packs? I will appreciate if anyone will share his/her experiences or direct me to any study where I will found such data.