Not all refrigerated trucks are created equal
Every day we see hundreds of trucks on our roads and highways. Many of these are refrigerated trucks transporting foods for human consumption. If the refrigeration were to fail, it would jeopardize not only the quality but potentially the safety of the products. Fortunately our truck transportation system is generally reliable, but occasionally problems occur.
Besides the obvious truck breakdowns, traffic tie-ups, and the occasional unfortunate accident, there are other ways food can be put in jeopardy. Trucks that have been on the road for a while may have cooling units that fail or do not function well, allowing all or part of the load to be exposed to elevated temperatures. Additionally, doors may not seal well, allowing cold air to escape and be replaced by hot air. Food packages near such areas can see temperatures beyond the required range. Likewise, given the state of roads and highways in the US, the integrity of the insulated box may be somewhat compromised by damage due to excessive or continuous vibration, thermal stress, and every constant flexing. Over time seams can open up or insulation can crack, break, and potentially crumble allowing cool air to escape, creating a warm zone near the breach.
One such cause can be leaks caused by insulation gaps or degradation from poor design, manufacturing flaws or road wear and tear over the life of a refrigerated trailer. Fortunately refrigerated trailer manufacturers have made investments to help insure that leaky reefers are not shipped and that insulation stays in place despite the continuous pounding they undergo while in use. One such trailer manufacturer is 100 year old Utility Trailer Manufacturing Company that claims to be the largest producer of refrigerated vans in the U.S.
Employing their “Foam-in-Place” trailer assembly and insulating process, Utility Trailer has developed a process to help eliminate all thermal gaps in the assembled unit. Refrigerated trailer and shipping containers have historically been made by insulating panels and assembling them. Newer insulation products displaced older ones in new designs; glass wool and vermiculite were replaced by foam core panels with tough skins for the truck body. These panels are bolted or welded together to make the trailer. This process has the potential to leave gaps in the insulation at the corners where panels meet.
Utility Trailer and other manufacturers have fine tuned the process by developing a completely assembled trailer enclosure (minus the doors) with gaps between the inner and outer panels of the walls, floor and roof. Comparisons of assembled insulated panel trailers and foam-in-place trailer shows potential for gaps in insulation can be minimized or eliminated by spraying foam insulation to the hollow cavity of trailer walls after assembly. Panel and trailer manufacture and assembly of the continuous foam insulation envelope requires new designs and materials to insure foam will enter every cavity and the structural integrity and durability of the trailer walls, floor, and roof are maintained.
There are several lessons that can be applied to all reefer trailers when considering this information. First, existing trailers may or may not have gaps in their insulation that create areas where refrigerated products could be exposed to excessive heat or cold. Thermal imaging can be a cost effective way for truck and fleet owners to inspect their rigs. Since these devices can cost several thousands of dollars, small fleet owners may want to use a service for such inspections. The good news is that most insulation gaps can be filled relatively easily with the same type of foam insulation used during construction. Many of us are familiar with such products from local hardware stores when we need to seal air leaks around windows.
The second lesson is after insulation gaps are addressed insuring perishable, temperature sensitive cargo is not subjected to out of specification temperatures for extended periods due to chiller breakdown or poorly sealed doors is still needed. Automatic monitoring of reefer temperatures during transit can help insure that the refrigeration unit is working and door ajar conditions are not present. Dairy, seafood, and pharmaceutical supply companies have used devices such as SmartSense’s flexible gateways with wireless sensor data logging and alarm system to continuously monitor box temperatures and send alerts to the driver as well as fleet office when out of specification conditions occur. This allows corrective action to be taken in real-time and provides a full log of cold chain assurance that products arrive in good condition.
Refrigerated transportation has been and will continue to be the backbone of our food and pharmaceutical industry. Insuring both that the refrigerated transport is sound and that when events do occur they are noted and addressed quickly has become more important as regulations about Cold Chain Custody are implemented. Companies with an eye toward the future can be early adopters and position themselves for market share gains as laggards decide whether or not to take the inevitable action needed.