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All PVC is not equal. Therefore, it should meet specific material property standards that are set by Cooling Technology Institute and can be found in (CTI) STD-136. The importance of CTI STD-136 is to set a minimum threshold for material quality for the cooling tower industry based upon material testing and real-world analysis of materials used in cooling tower applications. PVC material can range widely in terms of composition and chemistry. The addition of plasticizers, heat modifiers, UV inhibitors, and many other additives – which are used to address certain performance aspects of the PVC material – all have an effect on the mechanical properties of the PVC. Very inexpensive PVC can be formulated to be thermoformed and hold its shape for a cooling tower product, but the expectant serviceable life of that product never offsets the initial savings for going “cheap.” For a cooling tower application, heat deflection temperatures, UV resistance, impact resistance, and flammability of the PVC material are all important metrics. The ability of a product to operate properly under cooling tower temperatures can be directly related to the material’s heat deflection temperature, and the material’s ability to resist becoming brittle can be analyzed based upon its impact resistance and flexural modulus.
The discussion on specifying a quality material can take up chapters of a book. Understanding the manufacturing processes involved as well as how the material properties affect a product’s performance can become overwhelming. It’s important that minimal requirements are specified in order to safeguard against possible underperforming products. One simple specification line that can be incorporated by any Owner or Engineer is:
“The cooling tower [fill media / drift eliminators] shall be manufactured from roll stock that produces a finished product with a nominal [8/10/15/20] mils after forming sheet thickness as measure by CTI STD-136. Material must meet all CTI STD-136 material properties after production and the manufacturer must submit test results to the owner prior to shipment of actual material utilized for the project with traceability back to raw material.”
By knowing these important nuances to cooling tower materials, requiring a quality product can bring added value and peace of mind that your cooling tower fill and drift eliminators will perform as expected and that the specified products will have a long service life.
