scope:

This specification covers the most common thermoplastics used in the manufacture of film fills, splash fills, louvers, drift eliminators, nozzles and other small components for use in standard cooling tower application and the physical properties, burning properties and recommended testing procedures employed to determine the defined values, whether processed from virgin or reground material.

Materials covered by this standard are polyvinyl chloride; hereafter called PVC; chlorinated polyvinyl chloride hereafter called CPVC; heat elevated PVC hereafter called HPVC; Polypropylene hereafter called PP; and high density polyethylene hereafter called HDPE.

PVC - used in the manufacture of film fill, splash fill, inlet louvers, and drift eliminators. PVC by its nature has a low flammability risk, is low cost, easily thermoformed and extruded into complex shapes, and is rigid with minimal creep characteristics. PVC is not easily used for injection molded products. PVC has been the overwhelming material of choice for the aforementioned cooling tower components.

CPVC - used in the manufacture of film fill and drift eliminators. CPVC will add about 30^oF (16.67C) the heat distortion temperature of PVC so is it used for high temperature applications. CPVC is self-extinguishing and can be thermoformed. CPVC is much more expensive than PVC and can have embrittlement problems. CPVC and blends of CPVC are more susceptible to U.V. degradation and once exposed to U.V. will continue to degrade and lose impact resistance. Only select these products when PVC, HPVC, are absolutely unsuitable, and expect a material with much lower impact resistance and therefore a shorter useful life.

HPVC - used in the manufacture of film fills and drift eliminators, HPVC has a higher heat distortion temperature than PVC but lower than CPVC. HPVC is self-extinguishing and can be thermoformed. HPVC does not have the embrittlement problems of CPVC and will add about 15^oF (8.33C) to the heat distortion to the heat distortion temperature of PVC.

PP - used in the manufacture of injectionmolded products such as splash grids and thermoformed film fills. It is also used in other smaller components, such as nozzles. Due to its highly flammable properties caution should be used in applying this material in large quantities in application such as fill. PP material can be formulated to reduce flammability and in some cases designed to meet an E84 flame spread rating of 25 or less. Refer to section 2.1. The use of PP may require the cooling tower be designed with a sprinkler system due to its flammability. PP can not be solvent or adhesively bonded so for products requiring assembly; the design must include an alternate means to assemble. PP has a higher heat deflection than PVC and can add 15^oF (8.33C) to the distortion temperature if properly formulated to include fillers to add stiffness. PP inherently is softer and more susceptible to creep factors when loaded. Copolymers are much tougher and will impart better impact resistance to the part. PP has a density approximately 35% less than PVC and should be supplied in a thickness that allows the same overall part strength. However, the product shape or geometry also imparts physical attributes that may add strength to the product and must be taken into consideration as well as how thickness affects weather ability.

HDPE - used in the manufacture of injection-molded products extruded splash fill products. Due to its highly flammable properties caution should be used in applying this material in large quantities in applications such as fill. HDPE material can be formulated to reduce flammability and in some cases designed to meet an E84 flame spread rating of 25 or less. Refer to section 2.1. The use of HDPE may require the cooling tower to be designed with a sprinkler system due to its flammability.

Plastic film thickness is intrinsic to the weather ability and durability of the finished product, but not the only indicator of the suitability of the product. Material formulation, product configuration geometry and other properties all have an engineering value in determining the strength of the product. A standardized method for specifying and measuring film thickness is described.