A Polyurethane Primer
Polyurethane Manufacturing Methods
All polyurethanes are made by blending prepolymers and curatives in varying proportions and using one of two different manufacturing processes:
- Reaction Injection Molding (RIM)
- Open Cast Molding -- a) One-Shot, b) Hot Melt
Our cable covers from Peterson Systems are made using only the open cast method; one-shot for standard urethane and hot melt for the Hiperthane. Open cast is used exclusively because it employs a slower processing time than RIM and allows any bubbles in the solution to rise and dissipate. (If bubbles stay within the polyurethane, it can cause defects in the material.)
Types of Polyurethane and Their Features
The Peterson Systems products we sell come in two different materials: standard polyurethane and Hiperthane®.
Standard polyurethane is made using a quick, one-step, quasi-prepolymer process that blends chemicals to start a chain reaction that creates a hardened material. Tensile strength of this polyurethane is approximately 2,500 - 3,000 psi. Our standard Yellow Jacket® and Bumble Bee® cable protectors are both made with this type of polyurethane, which displays superior elongation (the percentage a sample will stretch before breaking):
- Quasi-prepolymer has elongation properties of 400% - 600%.
- Competitors using RIM processing can expect as little as 225 - 250% elongation.
Hiperthane® is engineered to a higher standard that other polyurethanes and can withstand heavier loads, higher abrasion, and greater impact over longer periods of time. Hiperthane® is much more puncture resistant than other urethanes and tougher than steel, with a tensile strength of 6,000+ psi. It's used in our Yellow Jacket with Hiperthane® cable covers.
More facts about Hiperthane®:
- All Hiperthane® materials go through an additional process of degassing. Any bubbles caused by pouring are torched off as they appear.
- Stays in mold for minimum of 45 minutes and takes at least one hour to set.
- Is heat set for 16 - 24 hours allowing for more complex, longer chemical chain reactions and fewer air bubbles.
- Denser than standard urethane, with a specific gravity of 1.25, versus 1.05 - 1.10 for quasi-prepolymer and RIM processes.
Choosing a Polyurethane Product
For frequent, hard use, Hiperthane® is the best, more durable choice. Yellow Jacket with Hiperthane® cable covers can withstand the heaviest loads and the greatest traffic.
For occasional use, try the standard Yellow Jacket® or the Bumble Bee®. The Bumble Bee® is designed for lighter loads (load per axle of 10,500 lbs), perfect for indoor environments. The Yellow Jacket® is better suited to heavier-use conditions where set-up and tear-down are more frequent.
The Yellow Jacket® has the same channel capacity as the Bumble Bee® but with a more gradual slope and softer material so it adheres to the ground better as traffic passes over. The arch construction at the leading edge absorbs initial impacts of oncoming traffic and helps prevent sliding.
The lids on all our cable protectors are designed to conform to uneven surfaces, and they use flexible fiberglass hinge pins for longer wear and resistance to impacts. The rounded dividers inside the cable cover help protect cables against pinching.
Polyurethane Cable Cover Usage Tips:
- Position the cable cover so traffic drives over the hinge side first whenever possible.
- Start by placing cables in the channel closest to the leading edge.
- Use grip tape to keep lids down.
- Use a drill to make anchor holes rather than spiking the product to reduce risk of tearing.
- Do not overstuff the cable cover... the lid can pinch the cable insulation.
- Replace worn parts immediately as torn lids can present a tripping hazard.
- Use end caps and other accessories to provide a clean, safe installation.
- Adhere to ADA guidelines for the use of wheelchair ramps.
- Avoid using solvents or acids to clean cable protectors; instead use ordinary soap and water or steam clean the product.
- Hiperthane should not be left unused or standing in a wet environment for long periods of time.