Humidity ranges outside of recommended standards can affect buildings, machinery, and equipment, apart from people. However, it is on the finished goods of manufacturing processes where it is possible to precisely measure the impact of uncontrolled humidity, as well as the manufacturing process itself.

“Humidity control has become increasingly critical in several manufacturing processes. Many products can only be manufactured in controlled humidity environments, including a wide variety of industries. In the pharmaceutical industry for example, the dehumidification process is critical in the handling of hygroscopic elements in several steps of the production. The food industry also uses extensive dehumidified air to control the contamination in cold storages and in powder food production processes, such as spray dryers which increase the productivity. Furthermore, dry air is essential in the manufacturing of glass, electronic components, optic fiber, capsule drying, seed storage, and more recently in lithium batteries for cars where the relative humidity cannot exceed 1%,” explains Danilo Santos, from Munters Brazil.

There are many situations where uncontrolled humidity conditions above the recommended levels can contaminate the production process. “In situations where factories do not have a good maintenance, or do not manage well the AVAC automation process, in industries such as the food manufacturing for example, high humidity can cause unbalances, alter textures, or change the characteristics of the recipes for products, generating losses when the products go through quality assurance,” says Amanda Salamone, from IMI HydronicEngineering.

Santos adds that environments with a humidity above the acceptable levels are frequently a growth-inducing factor for bacteria, fungi, virus, and other contaminants. “This condition can compromise the products' quality, impact the health and safety of consumers and cause significant losses in productivity.”

The answers to problems arising from humidity ranges out of established standards for each type of activity will vary depending on the production process. “Each application has specific strategies to control humidity. In cold goods storage for example, where temperatures are low, the solution includes avoiding condensation on surfaces (walls, ceilings, floors,) to control the spread of contaminants,” mentions the executive from Munters.

When thinking about non controlled humidity it is frequent to imagine an excess of humidity. However, ranges below the recommended levels are also harmful. In textile processes for example, they can be harmful due to the dryness of fibers, causing ruptures and loss of products. Processes with bad measuring, or with good measuring but badly managed textile expansion, without taking into consideration the execution of AVAC systems retrofitting, are environments enabling loss of control, explains Salamone.

“The ideal situation is to perform a correct measurement in the right environment, using two or more sensors in bigger rooms. The reference in these types of applications must be validated. There are cases where the measures with arithmetic averages comply with the process, however, in critical cases, using the ‘worst case' reference measurement in the sensor tends to result in better reading processes and updates through the PID controllers,” recommends the IMI director.

Cold storage need humidity control, especially when they are used to store produce such as fruits and vegetables, among others. This is required to avoid the products' dehydration. Vegetables are mostly water, with variations between 70% and 95% of their total weight, making humidity control a critical part to maintain the quality and original weight of the products for the longest possible time.

The control must be performed with appropriate controllers for the conditions of each environment which, to have a higher safety margin, must also be managed through software and apps. Full Gauge Controls has the MT-530E Super which is used in low and medium relative air humidity (from 10% to 85% with no condensation), and the AHC-80 plus, which is based on psychometrics (the difference between a dry bulb and a humid bulb) to measure the relative air humidity between 40% and 100%. Both communicate with Sitrad PRO. For bread fermentation chambers such as night bakeries, we offer the TO-751 model.

Cristiano Leste, from Applied Engineering in Full Gauge Controls