Use case: Control Cabinet in food industry

Desiccants in Closed System

Electronic components are highly sensitive to contact with condensation water. Rust formation and short circuits are the result. Switch cabinets that are operated at high humidity levels, large temperature differences or under frequent cleaning cycles – as is the case in the food industry, for example – must therefore be given special protection.

Control cabinets in the food industry

The increasing automation of production lines requires more electronic components. In food production, these are usually housed in stainless steel control cabinets. Condensation occurs here due to strong temperature fluctuations between plant shutdown and operation. The frequent cleaning intervals in the industry also contribute to moisture easily getting into a control cabinet, e.g. due to defective seals.

Formation of condensation in the control cabinet

Condensation in the control cabinet occurs when the air space inside cools down and the moisture contained in the air condenses. In our example, we are dealing with a fish processing plant which – as is usual for the food industry – is exposed to a normal room temperature of 20°C during standstill, but is strongly cooled during operation in order to ensure the cold chain of the products to be processed. High humidity prevails. Both the plant and the control cabinet are thus exposed to strong temperature fluctuations. If the control cabinet is opened, for example, at 20°C and a relative humidity of 90 % rH, approx. 16g per m³ will enter the interior. Even cooling down to 16°C would then cause the humidity to condense on the contacts and metal walls. This means that a temperature fluctuation of just 4°C is sufficient to cause lasting damage to a control cabinet under these conditions.

Use of desiccant bags

Desiccant bags are ideal for keeping the air in control cabinets dry. Silica gel bags as well as bentonite and superadsorber bags are suitable for this purpose.

Silica gel is used when the humidity in the control cabinet needs to be quickly reduced and kept at a very low level. With a capacity of 40% of the dry weight, silica gel ensures strong drying and, in the silica gel orange-green variant, also indicates to you in color when the bag is saturated and should be replaced.

Bentonite bags, on the other hand, are suitable if the humidity is to be lowered over a long period of time. The bags with water-permeable fleece or in the dust-tight variant with MILD absorb significantly more water than silica gel, but have a weaker bond to humidity. A color indicator is not available.

Superadsorber bags are the first choice when liquid water has already collected in the control cabinet. The bags absorb extremely high amounts of liquid water and can be laid out on the floor of a control cabinet, for example. With only 2g granulate weight already 150ml water is absorbed. In combination with silica gel or bentonite bags, the use is particularly effective.