With the cost of diesel fuel it can be tempting to use the refrigeration unit’s fuel saver mode, but this is not always the best decision.
In the fuel saver mode the fan may not be running at a high enough speed to move enough air to keep the ambient heat from coming through the trailer walls, says Rich Macleod of TransFresh Corp., Salinas, CA.
“You can’t afford to have that air movement capacity compromised in any way, because the load will warm up. We do see that over and over again.”
These problems usually occur because such decisions are based on the cost of fuel, he says.
“The (temperature) charts come in and you can see it on the recording thermometers. You get this up and down spiking on the recording thermometers,” Macleod states.
Then the reefer unit is unable to keep up with the demand for cold air and the temperature recorder shows this gradual warming up inside the trailer.
Hauling Wet and Dry Commodities Together
Although it doesn’t appear to be a major problem, Macleod says one of the things a driver should watch for during loading is when the waxed corregated cardboard is extending all the way from the top of the pallet to the trailer floor. This can block air flow to the pallets.
“From a practical stand point this is a reason the driver needs to watch the trailer being loaded,” Macleod observes. “You want to make sure that paper doesn’t extend below the base of the wooden pallet,” says Macleod, “but this rarely happens.”
In another scenario, he says shippers use a light grade plastic cap that goes over the top of the pallet, which effectively keeps the water from transferring from a wet commodity to a dry commodity. If the water reaches the cardboard of a dry commodity, then the container gets wet and collapses and damages the product. This can also lead to decay of a commodity that should remain dry.
“You are really trying to create a barrier to do that. Probably the most common is using a type of cardboard container covered with wax,” Macleod concludes.
(This is the final in a five-part series featuring an interview with Rich Macleod, vice president, pallet division North America for TransFresh Corp., Salinas, CA. He has been with the company since 1976, and has a masters degree in post harvest science from the University of California, Davis.)