Developed a blow molded coupling system for corrugated polyethylene pipe.
The system consists of an extruded EPDM seal that fits into the valley of a corrugation with a protruding lip that beds over and compresses as the pipe is pushed into the blow molded coupling. The configuration of the seal results in a locking action - less force is needed for the seal to stay in place than to back out.
The tricky part was getting the coupling sized right with the seal. Controlling the inside diameter of a blow molded part is not an easy, repeatable task, but it must be done for this product. Also, the wall thickness of a blow molded part tends to vary - as the parison is formed and droops from the die, the upper half tends to be thinner from the weight of the parison below.
The system consists of an extruded EPDM seal that fits into the valley of a corrugation with a protruding lip that beds over and compresses as the pipe is pushed into the blow molded coupling. The configuration of the seal results in a locking action - less force is needed for the seal to stay in place than to back out.
The tricky part was getting the coupling sized right with the seal. Controlling the inside diameter of a blow molded part is not an easy, repeatable task, but it must be done for this product. Also, the wall thickness of a blow molded part tends to vary - as the parison is formed and droops from the die, the upper half tends to be thinner from the weight of the parison below.
Built a testing apparatus to evaluate the system for DWV use (Drain, Waste, and Ventilation applications). Created a large clear acrylic coupling for testing seal function. The seal candidates were used inside the clear and the effects of vacuum could be seen visually.
The system and parts from a pilot run did pass the DWV standards, but the system was not an easy sell. PVC is the expected product for this application.
The system and parts from a pilot run did pass the DWV standards, but the system was not an easy sell. PVC is the expected product for this application.