It is essential to carry out testing of refrigerated trucks and vans to ensure that they maintain the proper temperature. Such vehicles are used for transportation and distribution of medicines, vaccines, processed food, frozen food etc. This article briefly explains the chances of failure of such vehicles.
Challenges & Recommendations for testing of cooled vans.
Due to the extreme ambient temperature, the cooling system of refrigerated vans has to be very efficient. We can assure this only be carrying out temperature testing of such vehicles. This test is generally known as Temperature Mapping Study. The main challenges and recommendations are listed below.
The loading should be done only after pre-cooling the vehicle.
Many users load the goods before the van is completely precooled and stabilized.
This will take up to 60 minutes in summer. The users do not want to wait this long.
The age of the cooled vehicle affects cooling capacity.
The engine and the cooling machine struggles to maintain the temperature after a couple of years
By the third year, the cooled vehicle has difficulty in maintaining proper temperature.
The vehicle might be able to bring down the temperature, but unable to maintain stability.
The Interval between door openings
Even after the opening of a door for 60 seconds, it takes 10-15 minutes to stabilize the temperature inside the cooled vehicle.
The duration for stabilization is determined in a temperature testing known as mapping study.
Proper discipline is to be practised on the frequency of door opening.
Door openings for Vans with 2 doors
This problem is severe for cooled vans with two separate doors (one on the side & one on the back).
The difficulties faced by frequent door opening is severe for vehicles with multiple doors.
The interval between two such door openings can be prescribed after a temperature mapping study.
The rear end takes a longer time to achieve the correct temperature.
The cooling unit is at the front end of the chamber of the cooled vehicle.
If the fan is not powerful, the cooling unit will automatically switch off before the rear end achieves the right temperature.
This necessitates the selection of the right capacity of the cooling unit for any refrigerated van.
The quality & thickness of the insulated wall
The insulation material of the body is critical in maintaining temperature stability.
The cooling down time, stabilization time after door opening etc. are affected by the quality & thickness of the wall.
The cooling unit selection should not be just based on the size of the van, but the frequency of door opening as well.
Most of the cooling units are provided based on the size of the vehicles.
However, for a vehicle with the frequent door opening, a higher capacity is required.
The sensor and the controller are the critical components.
Even an error in the sensor reading will cause high fluctuations
The sensors need to be calibrated.
The controller needs to be tested frequently.
The temperature behaviour is different under different load conditions.
Stabilization time, door opening frequency etc. is different under different loaded conditions.
Eg. The time for stabilization after a door opening is different in half loaded condition & fully loaded condition.
The temperature shown in the display in the driver’s cabin is never the right one across the entire van
The display only indicates the temperature near the cooling unit.
It will never be the same across the entire area of the van.
Even if the display shows 5°C, it is possible that some areas will be 9°C.
The data recorded inside the van with a data logger has to be at the weakest point
Users normally place a data logger or continuous monitoring system at a convenient location inside the van.
But this point has to be the weakest points inside the van (The hottest & coldest points)
Temperature Testing for Temperature controlled vehicles
Temperature testing of the vehicles involves a series of real-time testing mainly in the refrigerated cabin.
Temperature Mapping Study for Vehicles
Temperature testing by mapping study is the only way to understand the behaviour in each vehicle.
The behavior of two identical vehicles need not be the same under practical conditions.
Hence each vehicle needs to be tested.
Tests covered under Temperature Mapping Study:
- Pre-cooling time of the vehicle is tested.
- Ability to maintain temperature under 50% loaded condition
- Ability to maintain temperature under 100% loaded condition
- Time to stabilize after door opening of 1 minute, 3 minutes and 5 minutes.
- How long the vehicle can maintain the temperature after switching off the van.
Results / Recommendations after a Temperature Testing of Vans & Vehicles:
- The study will determine whether the van is good for the specified temperature.
- How long the vehicle should be precooled before loading the goods
- What is the ideal interval between door openings?
- What should be the setting of the temperature in the controller?
- Location for taking continuous readings for recording purpose.
- How long the vehicle will maintain temperature after switching off.
Summary of Temperature mapping study:
The following are the summary of details of a temperature testing of refrigerated vans and trucks used for medicine, vaccine, food etc.
- Test duration: 2-3 days
- No. of seasons: Summer & Winter
- Standards followed: WHO standards for temperature mapping study
To conclude temperature testing of refrigerated vans and trucks is essential in Middle East such as Dubai, Abudhabi, Sharjah etc. in UAE, Saudi Arabia, Oman, Kuwait, Jordan, Iraq etc.