How it Works: Why the diaphragm pump is an ideal option for foam extrusion.

by Shelly Coleman, Marketing and Sales Coordinator

In this segment of "how it works" we will be looking at the traits that make the diaphragm pump the best choice when it comes to foam extrusion. First, let's take a quick look at the operational differences between the diaphragm pump and the piston pump.

Gas Pumps in Commodore gas system stand

A diaphragm pump produces pressure via a reciprocating diaphragm disk. As this disk retracts, liquid is drawn into the opposite chamber through a check valve. When the disk protrudes back into the chamber, volume is displaced pushing the liquid out through a second check valve.

A piston pump consists of a piston which moves forward and backwards in a close fitting cylinder, attached to a crank that is rotated via an electric motor, and is fitted into the cylinder using seals. As the piston moves in the cylinder, suction is created, drawing liquid through a one way valve. As the piston moves in the opposite direction, the liquid is pushed out through a second valve.

The operation of both types of pump may sound similar, but the differences can be quite profound. Let's explore why the diaphragm pump is superior for foam extrusion:

Precise and fast metering

Diaphragm pumps are generally capable of higher precision metering when compared to the piston pump. This trait allows for more control during the extrusion process, resulting in improved repeatability, which ultimately produces a higher quality foam product with less waste.

Resistant to contamination

Due to the design, diaphragm pumps are less prone to contamination because they work without dynamic seals. The tighter seal inherent in the diaphragm pump virtually eliminates exposure to external emissions and contaminants to the liquids. Whereas the nature of piston pumps can allow mixing of the liquid with contaminants during operation.

Greater uptime and lower costs

Fewer moving parts and low wear on the components make diaphragm pumps more reliable than piston pumps. These factors also mean that diaphragm pumps can be rebuilt easier and faster, saving valuable time and money for any application. Due to the many additional parts and the nature of operation, piston pumps result in higher and more expensive maintenance costs, making them less desirable.

Safety when transferring flammable /hazardous materials

The diaphragm pump design virtually eliminates all chances of leakage, which offers superb safety. Even with an internal failure of the diaphragm, the pump housing remains liquid tight. Explosion proof electronics and gas detection systems may also be implemented as part of a complete safety system.

When comparing pumps for foam extrusion the above factors: accuracy, reliability, cost and safety need to be considered. After comparing the piston and diaphragm pumps, it is clear the ideal choice is the diaphragm pump, as it meets the demanding requirements of the foam extrusion process.

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