Summer is just around the corner, and the National Weather Service reports 113F as yesterday’s highest temperature (in Death Valley, CA). The summer months bring a heightened need to be vigilant when it comes to transporting refrigerated truck loads. Warmer temperatures outside, and an increase in the shipping of delicate produce such as cherries can be formulas for disaster if drivers don’t increasingly monitor aspects of their refrigerated truck load. Below are the 4 key areas that carriers need to monitor when transporting refrigerated truck loads in the summer months:
1) Ambient Heat & Trailer Temperature
Temperatures in the summer months in some states can reach up to 120F. This increases the internal temperature of anything enclosed in those conditions. We all have heard fatal examples of the result of extremely high heat temperatures inside cars in the summer months. In general, truck trailers can get up to 30F warmer than that the outside temperature. So, from our temperature report above, that means up to a blistering 150F. Therefore, it is critical that refrigerated trailers are maintained and operating accurately to be able to combat this high ambient heat.
2) Pre-cool
As per the Blue Book 2017 Transportation Guideline, a Carrier’s reefer system is not responsible for lowering pulp temperatures. Moreover, high pulp temperatures at delivery do not necessarily indicate a breach of contract by the Carrier because these high readings may be the result of a shipper’s failure to properly pre-cool produce prior to loading. When commodities with high rates of respiration (e.g. iceless broccoli florets) are loaded warm at shipping point, pulp temperatures may rise despite the Carrier’s maintenance of proper air temperatures in transit. It is the shipper’s responsibility to pre-cool the produce prior to the scheduled loading time to ensure loading can be accomplished without unnecessary delay.
In addition, if temperature control is required as it is in every case of refrigerated truck loads, the driver should pre-cool the trailer prior to loading. Standard procedure is for the driver to shut down the reefer unit while the trailer is being loaded.
3) Product Temperature
Prior to and during loading and unloading, drivers should make sure to pulp at least every other pallet of the product that is being loaded into their trailer. Then, drivers should write these pulp temperatures on the bill of lading. As per UWT’s loading guidelines, if the product pulp temperature reads higher than the requested temperature on the bill of lading, drivers need to address this variance immediately with the staff at the loading shed, and contact UWT immediately so that we can notify the customer. And remember, if access to the loading/unloading dock and pulping is not permitted, “shipper/receiver load and count” must be written on the BOL. These steps will ensure that drivers are protected and the burden of proof is placed upon the shipper. Additionally, this is even more critical as many products (such as watermelon) sit out in the field right up until shipping. The product’s temperature prior to transit must be reported, and more importantly, need to advise the shipper/customer of this temperature and leave it up to them to authorize moving forward with transit. If we do not do this and the product arrives “hot” upon delivery, we have no recourse to go back to the shipper.
4) Reefer Set Point
All reefer units have a ‘Set Point’; this is the setting that the driver must manually set the refrigerated trailer to run at, as per the BOL/Customer’s requested running temperature. All refrigerated truck loads must be programmed with a set point in “continuous” position. For example, if you have a set point of 33°F Continuous, the temperature reading displayed by the set-point will stay constant on a smart reefer download.
Moreover, it is important to note that on this “continuous” setting, the refrigerated trailer unit does have a set defrost cycle (defrost cycle is the process of removing ice or frost buildup from a coil). The intervals are factory set for every 6 hours, but the unit will auto defrost based on a temperature difference across the coil. The defrost cycle can be changed to compensate for produce that has higher heat respiration, for higher ambient temperature (ambient temperature is the certain temperature within an immediate environment), and for door openings. For example, if it is a humid day and the driver is doing a lot of door openings, you may need to have a more frequent number of defrost cycles. Although the reefer has this defrost cycle on continuous setting, it does not change the product temperature since most reefers have a very high heating capacity (heating capacity is the amount of heat energy needed to raise the temperature of a given mass of a substance by one degree Celsius). Therefore, the temperature in the air of the reefer heats at a faster rate than the temperature of the product that is in the trailer. The time of a defrost cycle is not is significant enough to affect the product temperature.
Make sure you are ready to take on the summer heat with the refrigerated truck loads you haul. Keeping these 4 areas at top of mind will help!
