When a leading U.S. pet food supplier encountered difficulties with its wet dog food processing line, the company realized that the sanitary rotary lobe pump it had been using in the line was not well suited to the conveying tasks. The company reached out to NETZSCH Pumps North America for a better solution. The experts at NETZSCH recommended a progressing cavity pump rather than a rotary lobe pump, given the specific demands of the application. After over 18 months of use, the NETZSCH progressing cavity pump installed in the line has proven to eliminate the process concerns of the rotary lobe pump that had been causing downtime and lost profits.

One leading U.S. pet food company manufactures a line of wet dog food products in a facility in Arkansas. The manufacturing process at the factory starts with frozen pieces of ground meat. The larger pieces are broken up and transferred to a cooking station via a screw conveyor. At the cooking station, the meat is prepared to the required specifications and the gravy sauce is added. The meat with gravy emulsion then goes into a dynamic mixer, and from there to the filling and packaging station.

The company had been employing sanitary rotary lobe pumps to transfer the meat emulsion with gravy both from the cooking station to the mixer and from the mixer to the filling and packaging station. These lobe pumps were not able to handle the high pressure clean-in-place (CIP) process that the company required, and this made the cleaning and sanitation process difficult. These difficulties led to unplanned downtime, high maintenance costs, and loss in production.

In part, the issue arose because rotary lobe pumps are inherently limited in their ability to handle pressure, and therefore were not ideally suited to this application, where the high-pressure CIP process is necessary. In ideal circumstances the maximum may be 230 psi (16 bar), but for most practical purposes in many applications pressure may be problematic beyond 145 psi (10 bar). Lobe pumps are also very sensitive to the range of viscosity and thickness of slurries and emulsions.

The company contacted NETZSCH, which has over 60 years of experience in similar pumping applications, for an improved pumping solution.

NETZSCH is the world market leader for progressing cavity pumps, and an expert in positive displacement, rotary lobe, and multiple screw pump technology.

Experts from NETZSCH noted that unlike rotary lobe pumps, progressing cavity pumps can handle greater pressures, a wide range of viscosities, and the variability of slurries and emulsions. In addition, progressing cavity pumps feature pump performance that is not affected by the variations and changes that occur during this company’s production and cleaning processes. Progressing cavity pumps also offer a positive sealing effect between the rotor and stator creating distinct cavities, which permits the handling of higher pressure per stage than rotary lobe pumps.

After studying the application, NETZSCH experts presented NEMO^® progressing cavity pumps as the best solution for transferring the meat and gravy emulsion from the cooking station to the mixer, and from the mixer to the filling and packaging station. In addition to solving the problem presented by the high cleaning pressure, the progressing cavity pump also improved the consistency of the emulsion due to its gentle shear characteristics.

NETZSCH delivered NEMO® pumps in all 316 stainless steel polished construction with tri-clamp CIP and discharge connections to this customer. The pumps employ a stainless steel washdown motor for ease of cleaning, and were mounted on stainless steel baseplates with wheels and a handlebar for ease of movement.  The open hopper and feed screw of the NEMO pumps provide a smooth entry for the emulsion in the suction housing of the pump and into the conveying elements.

The stator material selected was an elastomer compound, which complies with the FDA Standard 177.2600 Code of Regulations Title 21. This material offers a good balance of thermal properties as well as rheological properties to handle high pressures and enhance the service life of the stators. NEMO pumps are carefully designed to ensure precise interference between the rotor and stator, thereby delivering the maximum possible pressure per stage. NETZSCH manufactures all components to a high degree of accuracy and tight tolerances to provide consistent performance for extended service life and minimum maintenance.

The two-stage NEMO progressing cavity pumps installed at this customer’s facility have been operating successfully for more than 18 months. They have proven to be easily capable of handling the higher pressures of the company’s CIP process. In addition, the pump has proven to deliver the added benefit of even handling any pressure surges that may occur during normal operation. The temperature of the emulsion ranges between 37 and 86°F (3 and 30°C), while during the CIP process, the temperature ranges from 140 to 175 °F (60 to 80°C); despite this wide temperature range, the pump components have proven to have a long service life.

The customer has expressed satisfaction to NETZSCH with the performance of the pumps and for the simplified CIP process. Since the pumps nearly eliminate the unplanned downtime, maintenance costs, and loss in production that plagued the previous rotary lobe pump, they provide the customer with a lower total cost of ownership and higher line profitability.