The quality of steam in the food industry is a critical element, especially when it comes into direct contact with food. It is essential to take all necessary measures to ensure that, during installation, control and maintenance of steam generators, steam is always of the appropriate degree of purity.

Steam is the most energy-efficient, reliable and flexible means of heat transfer for activities related to food and beverage processing. It is widely used throughout the supply chain, from production to processing and packaging of many foods and beverages and is very often in direct contact with the product itself. It is therefore appropriate to take precautions to minimize the potential risk of contamination that may be dangerous for the final consumer.

For a correct action in the sectors related to the quality/purity of steam in the food and beverage sector it is good to keep in mind:

• The various grades of quality available for steam and the best way to get them;
• Potential sources of contamination resulting from the use of an inadequate vapor purity grade;
• The best design, maintenance and control of steam systems.

Currently there are various regulations, guidelines and laws that ensure the production of hygienically safe food. Nevertheless, the legislation is still rather poor (particularly in the European context) with regards to the guidelines for the quality and purity of steam in direct contact with the product or the production process. The one to which we most commonly refer is the Standard 173.310, of the FDA (Food and Drug Administration) Federal Regulations, Title 21, Volume 3, Revision of April 1, 2005.When using steam, it is important that any organization knows the meaning of steam purity and quality in the process.

‘Steam quality’ is a characteristic definition of steam systems and indicates the percentage of water in the steam, without taking into account other contaminating elements. A more precise definition of this factor is ‘dry fraction’ of the steam, i.e. the ratio between the flow rate of the steam and the sum of the steam flow rate with the entrainment of water.

The purity of steam, on the other hand, is the measurement of the quantity of solid, volatile substances or other particles dissolved in the vapor that can remain trapped, following the primary separation in the boiler.

The plant steam, also defined by the term industrial steam, is the starting point of all the degrees of steam used in food and beverage production. The plant steam is certainly suitable for all applications where it is not in direct contact with the production and processing of raw materials intended for food, for example when it is used in heat exchangers, boilers or hot water generators. Otherwise, if it is used in direct contact with the production process, its quality/purity must be taken into consideration when entering the production cycle.
The plant steam is normally produced using pre-treated water, both for softening, for de-alkalization, and for reverse osmosis (RO); subsequently it is preheated and chemically treated, to prevent potential corrosion, deposits and encrustations.
The plant steam should always reach its point of use at the correct flow rate and pressure, clean, dry and free from air and other non-condensable gases. Moreover, when possible, the condensed steam (resulting from the steam once it has yielded its latent heat) should always return to the boiler to be reused, thus allowing the reuse of precious energy and the recovery of water and chemicals with both economic and environmental benefits.

In the production of plant steam, however, there are some factors that can potentially alter the quality and purity of steam. This happens when the water is chemically treated to contain the formation of encrustations, corrosion and chemical attacks within the system itself. However, entrainment also contains potentially high levels of chemical substances for the treatment of boiler water which come in the form of foam. Since boiler entrainment is conditioned by many different factors, discontinuous checks often do not allow the correct identification and/or the reason for the entrainment.

It is therefore necessary to perform periodically:

• Chemical controls of additives in the boiler, which must be in line with a boiler water treatment program and “must not exceed what is necessary for its functional purpose …” (as defined in the FDA standard).
• TDS (Total Dissolved Salts) Controls that must align with the recommendations provided in the published guidelines, and make sure that the TDS levels minimize the effects of foaming or between the surface of the water and the steam trap. The automatic control systems of TDS are the best solution to keep the boiler at the pre-set optimal limits.
• Condensation check through periodic analyses of condensation and steam samples to ensure the correct functioning of the water treatment system. This sampling must be taken at the condensation outlet just before the point of use in the process. Steam sampling must be carried out via a sample cooler, fitted immediately before application to the process.

In summary, the quality/purity of the plant steam is determined by the following factors:

• The quality of feed water.
• The number of additives and the subscription to a water management and treatment program.
• The correct boiler operation, for example load, level control systems, TDS control systems, working pressure, etc.

The chemicals for boiler produced by Technoacque contain chemical agents approved by the Food and Drug Administration (FDA – USA) for food and beverage production according to the accepted concentration levels. Technoacque experts will be happy to provide you with any kind of information on chemical products and water treatment solutions, do not hesitate to contact us.