Tag Archives: polypropylene

Common Plastic Terminology for Trench Drains

It’s time to discuss some plastic terminology!

Disclaimer: I am not an organic chemist or a plastics engineer. I’m gathering this information from other sources and I may not be explaining it as accurately as I need to.

Polyolefin — is a polymer produced from a simple olefin, or alkene as a monomer. For example, polyethylene is a polyolefin produced by “polymerizing” the olefin “ethylene”. Another common polyolefin is polypropylene. I consider polyolefin a general term for a family of plastics. (http://en.wikipedia.org/wiki/polyolefin)

Polyethylene — is a semi-crystalline plastic with excellent chemical resistance, good fatigue, and wear resistance. They can have a wide range of properties which are determined by the length and degree of branching of their polymer chain. In general, polyethylenes have good resistance to organic solvents, high impact strength, are light weight, resistant to staining, and have a low moisture absorption rate. They are easy to distinguish from other plastics because they float in water. (http://en.wikipedia.org/wiki/polyethylene)

HDPE (High Density Polyethylene) — HDPE is the most common polyethylene used in industry. It offers excellent impact resistance and high tensile strength. Technically speaking, it has a low degree of branching and thus a stronger intermolecular forces. HDPE is non-toxic and meets FDA and USDA certifications for food processing. It is commonly used for the manufacturing of milk jugs, margarine tubs, detergent containers and trash cans. It is also an excellent material for use in trench drain and storm sewer pipe.

Polypropylene is an economical material that offers a combination of outstanding physical, chemical, mechanical, thermal and electrical properties not found in any other thermoplastic. It has a lower impact strength that does HDPE, but it also has better tensile strength and superior heat resistance.

Structural Foam — is a structure imparted to an olefin during processing that gives the plastic addition strength and resilience. More on this later.

PVC (Polyvinyl Chloride) — Is a widely used thermoplastic polymer. Over 50% of the PVC products manufactured are used in construction as a building material. PVC offers excellent corrosion and weather resistance and has a high strength-to-weight ratio. PVC is inexpensive, easy to clean, and a popular replacement for wood and concrete building materials. It is used in house sidings, drainage pipe, window profiles and plumbing fixtures (such as some trench drain). Despite appearing to be an ideal building material, concerns have been raised about the costs of PVC to the natural environment and human health. (http://en.wikipedia.org/wiki/polyvinyl_chloride)

Fiberglass Reinforced Polyester — Polyester is a category of condensation polymers which contain the ester functional group in their main chain. This group also includes polycarbonates. Polyesters are popular for being used as a woven fabric. When fiberglass is added to polyester, the resultant material is more durable and resistant to impact.

UV Inhibitors — These are chemical additives that are added to plastic which help to retard the damaging effects of ultraviolet light to the plastic.

Injection Molding — This is a forming method by which intricate trench drain products (or other plastic shapes) can be shaped. In this process, a heated and liquid thermoplastic is injected into a mold that contains a cavity that has the shape which is desired. Once injected with plastic, the mold and part is cooled. The resulting plastic shape is removed from the mold and trimmed of flashing (excess plastic). This method is needed to form pre-sloped trench channels. Though mold costs are expensive, one mold is required for each size of pre-sloped channel.

Extrusion — Another method of making trench channel is extrusion. In this process, a heated batch of thermoplastic is continuously injected through a water-cooled die. The shape of the die will determine the cross-section of the extruded part. This method can be used to make simple, non-complex parts such as pipe, tubes and u-shaped channels. The most inexpensive channel drain products are made using this forming method.

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Pro’s and Con’s of Plastic Trench Drain

When I started my career with trench drain, I didn’t know the critical questions that determine whether plastic trench drain is appropriate in a drainage project.

At the time, I handled a polymer concrete product line. Polymer concrete is a mixture of an inert material (such as silica sand) and a two part polyester resin binder. The sand-resin mixture is poured into a mold, where the bond sets and the shape dries. Further curing can then be done in large driers. The resultant product is heavy, hard, durable, and brittle.

My sales manager instructed me that polymer concrete trench drain products were “good” or “superior” and plastic products were “bad”. Of course, he had a vested interest in promoting his polymer concrete trench drain. It made me ponder the reasons that lead to the contractor’s decision to use one material versus another material.

Since then, I have seen enough applications and selling situations of trench drain to have legitimate opinion on what is “good” trench drain and what is “bad”. And, from what I’ve seen, it’s all good…depending on whether or not you have the proper application.

When looking for a trench drain product, determine what is needed and what can be sacrificed. Where is the project? Is the aesthetics or functionality more important? Are you or someone else installing the product? What equipment is available to use in the installation? What are the load requirements for the drain? What is the budget? All these are necessary questions to the drain selection. And, all may have an impact on whether you use a plastic based product. Selection considerations are discussed below.

Advantages of Plastic Trench Drain:

trench drain grates, trench grates, channel drain grates, channel drains, plastic trench drain, patio trench, patio drain, drain channelGreater Selection Options — Plastic trench drains come in many widths, lengths and styles. Products are available in 1” to 21” widths and can come in up to 10 foot lengths.  Narrower channels use lightweight grates with decorative options.  On the larger side, plastic trench drains can use heavy duty iron grates for situations with heavy vehicle traffic.

Plastic Trench Drain is Light Weight — Being lightweight gives plastic trench drains two benefits:

  • Easier handling during installation — One person can handle a 10 foot section of drain. Other products, such as polymer concrete and fiberglass, are heavy and come in shorter lengths.
  • Better shipping — Small orders of plastic trench drain can be shipped by UPS or Fedex. Similar orders of polymer concrete product would require a freight hauler and a fork truck to unload.

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Ease of Installation — The high degree of processing sophistication allows for superior trough designs that promote an easy installation. The designers thought through the contractor’s process and came up with plastic drainage systems that are both adjustable and quickly installed.

Lower Product Costs — Plastic trench drain is more affordable than polymer concrete drains at widths up to 8”. Plastic systems also offer a wider range of decorative grating options, corner angles and color choices.

Forgiving to Impact (at times) — If you drop a section of plastic trench drain on the floor, it won’t break like polymer concrete will.

Disadvantages of Plastic Trench Drain:

Freeze/Thaw problems — Plastic has a higher coefficient of thermal expansion than does polymer concrete. This can lead to problems in environments that see extreme cold and heat. The trench drain can separate from the concrete that holds it in place.

Extreme Cold Impact Problems — Some plastic will shatter if it sees an impact while frozen. Some plastic trench drain will do the same.

Low Industrial Strength — Some plastic products promote their ability to handle heavy load applications. And though the grate they provide may meet the load requirement, the channel itself may display low integrity.

Durability — In general, plastic trench drain doesn’t have the life as polymer concrete.

This list of advantages and disadvantages is not exhaustive. It’s just what I can think of today. Maybe you have some other ideas. If so, let me know. Email me with comments or questions! Feel free to speak to one of the professional sales staff at Trench Drain Systems by calling 610-638-1221.

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