It is understandable that many companies like their crates, pallets, trays, etc., to be dry after washing and before being refilled. Either owing to the limited shelf life of delicate vegetables and fruits, for example, or because of the risk of accelerated bacteria growth if there is residual moisture in the crates.
In the requests we receive, the requirements vary from 90–95% dry (or, for example, 5 grammes of residual moisture) to 100% dry. The latter requirement comes principally from the automotive industry, where parts susceptible to rust are involved. 

In order to find an appropriate solution for such intensive drying of products, it is essential that we receive a number of examples of such parts.
This allows us to carry out extensive testing and thereby come up with the best possible solution, including a guarantee of the desired drying result.

The first possibility for drying such products is to use an airblow system. In this system, fans blow ambient air over the product at high pressure and high speed. The air is the same temperature as the environment in which the machine is placed, plus the heat generated through the power of the fans. This is usually around 20°C.
The capacity of the fans, and therefore the speed of the air, depends on the type of product washed. Many crates, for example, have a lot of recesses on the outside. There is a considerable risk of a lot of water remaining in these. In such a situation, we recommend a blow-dry system with 2x 5.5 kW fans. The water is then blown from the crates at a pressure of 20 kPa.

Products with a very smooth structure – for example pallets – require a somewhat different approach. In this case, the blades are as large as the surface area, and have a very narrow aperture. In addition, 2x 8.5 kW fans are used, increasing the air pressure. The blades are positioned at an angle to the product, so the water is ‘scraped’ off this, as it were. The airblow system gets the products ‘almost’ completely dry.

If an absolutely 100% drying result is required, the airblow system alone is not sufficient.

A drying tunnel will do the job, however. With this system, electrical heating is used to blow hot air, at approx. 100°C, onto the product. Unlike the blow-dry section, here the drying result is not determined by the air pressure, but by the amount of time spent by the product in the machine. If the speed of washing and drying has to be increased, the drying tunnel must be made longer to keep the drying time the same.
The drying tunnel works best if the products are free of droplets. For this reason, the tunnel is often placed behind the exhaust system. Removing droplets can also be achieved using a ‘shaker’, however.

The centrifuge is a completely different drying method. This principle only works for crates. The system is interesting in relation to very high capacities (approx. 2,000 crates per hour). The crates are gripped 6 at a time by the machine’s arms and revolved at a speed of 450 revolutions per minute. Two rows of 6 crates can be placed in the machine. Thanks to its low power consumption, the crate centrifuge is very efficient. This makes it not only cheaper, but also better for the environment. The braking energy released when the machine stops abruptly after rotating can even be used to heat the washing water in the washing machine. In this way, optimum energy saving can be achieved.

This machine is also attractive from a working conditions point of view, owing to the low level of noise emissions. And this without any form of insulation. Although the centrifuge is not cheap to buy, a simple calculation quickly reveals that its payback period is only 3 to 5 years, unlike conventional driers. Naturally, this depends on the number of operating hours per day. If you are interested in our calculations, please feel free to contact us. We will be happy to calculate the benefits for you.

It is also worthwhile asking about the possibilities for environmental subsidies in the country where your business is based. Many countries give subsidies for the purchase of energy saving industrial machines.  
All Numafa CL drying systems can also be installed in a third-party line.