Gas Systems for Foaming Plastics - What You Should Know

by Kurt Bartosch, Engineering Manager

In order to operate a profitable foam plant, it is critical that your extrusion lines operate 24 hours a day, seven days a week, while maintaining consistent output and quality. With the complexity inherent in a foam extruder, this can be a challenging objective. While there are numerous sub-systems in an extrusion line that have the potential to fail and interrupt the process, the component that seems to be the source of the most anxiety for our customers is the gas injection system. Historically, gas systems have tended to be very complex systems, both difficult to operate and hard to maintain. These factors often result in inconsistent blowing agent flow, or worse yet, unplanned downtime.

The ability to produce high quality foam relies heavily on the repeatability of the process. The gas system can't deliver consistent amounts of the blowing agent unless the supply to the pump is clean and free of any foreign matter. For this reason, our system begins with a low pressure fluid filtration system, which removes impurities before they can reach the pump heads, thereby protecting the components and ensuring longer uptime.

Completed gas system on stand

Our experience in foam production has shown us the importance of employing gas pumps with multiple isolated pump heads. Compared to a single-head unit, a dual or triple head pump offers a significant advantage in uptime. By utilizing multiple heads, you can maintain and/or repair one head without interrupting the extrusion process. Simply isolating one head will allow service while the remaining pump head(s) deliver gas to the extruder without interruption.

This uninterrupted supply of gas to the extruder is important, but the ability to precisely measure the pump's output to the extruder barrel is just as critical to the process. In order to quantify the output, we employ a precision Coriolis flow meter, allowing us to measure the exact mass of the blowing agent as it is sent to the extruder. This precision leads a more dependable process that results in consistent high quality foam sheet.

Multiple gas systems in use

Another area of concern with a high pressure gas system is safety. The inner workings of the gas system can seem like a mystery, and understanding the potential hazards can be a challenge. We have designed in numerous features to ensure safe operation of the gas system. To safeguard against a dangerous overpressure situation, we include pressure relief valves on both the low and high pressure side of the system. The pumps we specify for our systems use dual Teflon coated diaphragms equipped with a rupture detection system. This feature warns of a ruptured pump diaphragm before the system fails. Finally, all of the electronics in the system are explosion proof. These safety features ensure that your gas system, when properly installed, will provide a high level of security for your personnel and your plant.

As you have read, when it comes to gas injection systems, there are many features that are critical for the consistent production of high quality foam sheet. Commodore's gas injection systems are designed and built to the highest standards, using only the best components available. Your efficiency and profitability will benefit, while giving you the peace of mind that this complex system will no longer be a concern for you and your team.