eeping milk products at optimal temperature is a critical concern for dairy processing. Safety and quality are both highly reliant on maintaining product holding temperatures in the narrow range of 36 to 38 °F. The industry is highly regulated, so the need for reliable compliance is a perennial concern. At the same time, in common with a wide swath of other industries, dairy processors must increasingly consider the goal of sustainability.
Secondary cooling systems using glycol, chilled water or brine loops, keep dairy foods at temperature after extraction and pasteurization, and during other periods of intermediate and final product storage, such as holding in storage tanks, or cheese maturation. Nevertheless, wise material selection is needed to prevent these systems from creating headaches of their own for process managers.
Traditionally, secondary cooling systems have been built using post-insulated metal piping. However, the inevitable process of corrosion can compromise the integrity and lifespan of metal installations. Leaks from corroded pipes not only call for expensive repairs, but often replacement, with equally expensive downtime. Corrosion occurs not only on the outer surface, but also on the inner surface of the pipelines, and its build-up can lead to flow reduction that may bring loss of efficiency. The process of insulating metal pipes, which takes place once the pipeline is completely installed, can itself give rise to future problems. The insulation type and thickness are chosen in order to avoid condensation, and help maintain stable temperatures along the line. However, any gaps between the outside surface of the pipe and the insulation will bring condensation that may lead to under insulation corrosion (UIC), which is one of the top reasons for repairs. Without adequate vapor sealing, water intake can degrade the insulation and potentially lead to the appearance of undesirable mold and bacteria, thus contaminating the facility.
Technological advances in the last decades have brought plastic piping systems to the forefront of the material selection process. Pre-insulated piping systems made of high density polyethylene (HDPE), with high-quality closed cell polyurethane insulation, protected by a robust and UV-resistant HDPE outer jacket, have become a welcome alternative to problematic metal piping in secondary cooling. Besides being corrosion free, the smoothness of the inner wall of the plastic piping components prohibits build-up of deposits from the fluid, preventing the reduction of flow in the pipe throughout the lifespan of the system. This smoothness of the inner wall will likewise reduce pressure loss, increasing the efficiency of the cooling loop. Given this capability, it is unlikely there will be a need to replace components within the system’s entire expected operational lifespan of 25+ years, meaning no downtime; a serious boost for cost-effective productivity.
The high-quality and high-density insulation is manufactured directly on the pipes and fittings and bonded to an external hard jacket at the manufacturers, an approach with multiple advantages. This method removes the possibility of gaps or damage in the insulation, while providing reliable water and vapor sealing – ideal for rooftop applications and indoor washing procedures. The insulated pipes are joined together in a highly reliable manner through the process of electrofusion. Electricity is passed through a resistance that is already embedded in every fitting, heating up the inner surface of the fitting against the outer surface of the pipe and fusing it permanently. This machine-assisted, long-established technology allows for a fast jointing procedure with a reduced human factor.
Pre-insulated plastic also offers improved energy efficiency, a key point as sustainability becomes an important objective. The hard external jacket on the pipes and fittings maintains the integrity of the high-quality closed cell insulation, thus precluding thermal bridges. Together with the low thermal conductivity of HDPE versus metal, this will minimize energy loss. The overall result is greater stability of temperature along the line, which may reduce the difference between the outlet temperature of the chiller, and the desired temperature at the consumer point. Plant operators may even be able to set the chiller at a higher temperature, which will reduce the electricity cost. Plastic is also more sustainable than metal in that it requires less energy to produce. Given its lower weight, it requires less energy to transport as well. As major manufacturers increasingly evaluate all emissions produced along every step of the value chain, the lower carbon footprint of pre-insulated plastic piping systems will be an increasingly valuable benefit.
When it comes to installation and building design, pre-insulated plastic piping systems again offer advantages over post-insulated metal. With the piping already insulated and encased in its outer jacket, the installation can be performed in half of the time and by a single team, rather than requiring coordination among installers from different trades. The choice to use plastic lowers the system’s weight by as much as 65%, creating the option of pre-fabricating pipe assemblies either on- or off-site, saving time and reducing the potential for errors. During the installation phase, this weight difference will ease the handling on site, reducing the hours for mechanical equipment, such as cranes, and lowering the risk for accidents. The combination of lower weight, UV resistance and vapor sealing, also allows designers the flexibility to place lines on the roof, rather than at a high height indoors. The low weight of plastic means that it may still be possible to place other substantial items on the roof as well, instead of needing to give them high-value space on the floor level.
Secondary cooling systems will remain vital to dairy operations, and material selection can set the stage for success. Pre-insulated HDPE piping systems are a reliable and sustainable choice allowing plant managers to sidestep maintenance and contamination problems, while streamlining installation and optimizing the use of energy. With greater peace of mind from a low-hassle, long-lasting cooling solution, dairy producers can do what they do best: focus on the quality of the delicious and nutritious goods they work so hard to deliver.
Angela Sampaio is Business Development Manager Cooling—USA at GF Piping Systems. She has extensive experience with the design, installation, and operation of secondary cooling systems in a wide variety of industrial settings. For more information, see https://www.gfps.com/en-us/products-solutions/systems/cool-fit-4.html or contact angela.sampaio@georgfischer.com; phone (949) 343-3713.