DRC’s Trading Assistance Staff has contacted Thermo King to understand better how a reefer unit operates and to learn what they recommend as best practices for transporting fresh fruits and vegetables. Here’s a list containing valuable insights you can use when preparing your next load:
PRE-LOADING
✔ Pre-cool and store cargo at a desired temperature to remove heat.
- Confirm the product is at the desired temperature before loading.
- Refrigeration units are designed to maintain temperature, not to change it.
✔ Run Reefer Unit 20 Minutes in “High Speed Cool”.
- To remove residual trailer/body heat.
- Perform Automatic “Pre-Trip” to confirm proper unit operation.
- Unit: MUST” pass test.
- If Auto Pre-Trip fails, follow your company’s prescribed procedures, or contact your local dealer for assistance.
✔ Set unit controller to the desired temperature.
- Verify the settings after changing it to confirm that it is correct.
✔ Select Mode of Operation.
- “Continuous Run” or “Cycle Sentry”. For fresh fruits and vegetables, always run the unit on the “Continuous Run” mode.
✔ Pre-cool trainer and truck body.
- To desired temperature to remove residual heat.
LOADING
✔ Turn the unit “OFF” while loading.
- To minimize heat and humidity entering trailer / truck body.
- Verify product is at proper temperature.
✔ Load Product quickly and efficiently.
- Provide adequate air circulation around and through the entire load.
✔ Close doors and start unit.
- Re-confirm Continuous Run operating mode and set point temperature.
✔ Strip curtains.
- Always recommended in distribution.
- Keep conditioned air in and outside air out.
✔ Door openings.
- Minimize the number door openings and their duration.
- Ambient air migrates in, and trailer / body air migrates out.
TRANSPORTING
✔ Proper airflow is CRITICAL.
- Poor air distribution causes product deterioration, even with adequate unit capacity.
- Obstructions cause poor air flow and product hot spots.
- Proper air circulation: Unobstructed paths on all 6 sides of load.
✔ Good airflow has 4 Key Factors:
- Use three-way block pallets to help provide adequate air flow.
- Do not obstruct floor under cargo. It prevents air from returning to the unit.
- Slip sheets and hand stacking are not optimal for temperature management.
- Inside of trailer / body must be clean to prevent contamination:
- T-Floor must be free of obstruction.
- Debris can block air circulation.
- Debris can be pulled into unit, resulting in insufficient cooling.
- Use loading patterns that provide adequate air pace.
- Exercise Caution!
- Provide adequate air space between top of the cargo and ceiling.
- Products should be loaded evenly to avoid air flow restrictions.
- Do not block unit evaporator air inlet (return air). It restricts air flow.
- Do not load product tight against unit, walls, or doors.
- Do not load product to ceiling. It causes air to short cycle.
VERIFICATION AND FURTHER RECOMMENDATIONS
✔ Verify Pre-cooling.
- Pre-cooling product and trailer / body to desired temperature prior loading.
- Position trailer / body tight against dock seals when delivering. Supervise opening and closing of doors.
✔ Do not operate unit with doors open.
- Until will blow conditioned air out and draw outside air in.
✔ Keep doors closed whenever possible.
- Keep door openings few and fast. Cold stays in, heat out.
- Turn unit “off” before opening doors.
- Box temperature recovery time is significantly increased by the entry of outside air.
- The greater the difference between set-point temperature and actual box temperature, the longer it will take to recover back to set-point.
✔ Use strip curtains.
- Strip curtains reduce internal and external air exchange. This helps to limit interior temperature changes.
✔ Non-refrigerated docks:
- Turn refrigeration unit “off”. Minimize product exposure to ‘improper temperature areas.’
- Maintain an effective seal between trailer / body and dock.
✔ Refrigerated docks and refrigerated cross docks:
- Back trailer / body tightly against docks seals before opening doors.
- Minimize door openings.
✔ Cross docks distribution:
- Move product quickly. Minimize the time it will be exposed to ‘improper temperature areas.’
✔ Ground delivery for:
- Supermarkets
- Convenience stores
- Restaurants
- Direct Store Delivery
✔ Turn refrigeration unit ‘off.’
✔ Minimize door openings.
✔ Use strip curtains.
The information in this article was provided by Randy Green of Thermo King Eastern Canada, Ontario Division.
Contact: Randy Green at rgreen@thermoking.ca
Thermo King, founded in 1938, is the world leader in manufacturing transport temperature control systems for a variety of mobile applications including trailers, truck bodies, buses, shipboard containers, and railway cars. Thermo King products are backed by a nationwide dealer network which provides expert factory-trained service and a complete line of genuine and competitive parts.
