Eccentric Disc Pumps Eliminate Food Waste

A large, private-label food processing and packaging facility in Hayward, Calif., experienced inefficiencies in its operations that cost thousands each day in wasted product. The company specializes in custom food manufacturing of more than 100 different sauces, seasonings, dressings, marinades, soups and dry mixes for retail, wholesale, food service and industrial needs. A crucial stage in its production process occurs in the packaging area, where many of its products are pumped into pouches or packets and then sealed and cut into individual pieces. The filled pouches are sent to a line at which they are weighed. Those that meet the pre-determined weight are packed for shipment to the end user, while those that are either too far overweight or underweight are rejected and eventually disposed. The operational reliability of the pumps determines if the pouches receive the proper volume of product, be it sauce or soup. Recently, the facility’s operators began to notice that many pouches being produced were over or underweight, leading to an increased amount of waste. This affected the company’s bottom line because good products were unable to be sent to the end user. “We were using lobe pumps for filling our 6- and 9-ounce pouches and were experiencing a loss of around 15 to 20 percent, depending on the product, because of the cavitation of the pump,” explained the facility’s production manager. “With the lobe pumps, we just had too much variation in their operation, and they weren’t able to consistently inject the proper amount into the pouches.”

Dealing with Waste

Realizing that the packaging operation could not tolerate this much waste, the production manager’s search for a solution led him to a supplier of pumps and related equipment in the western U.S., with operations in California, Arizona and northern Mexico. The rejection of overweight and underweight packages on its barbecue sauce line was a problem, with 300 to 400 pounds of rejected packets on an eight-hour shift. That amount of waste in eight hours costs a lot of money. That is enough waste product to fill a 55-gallon drum. After examining the company’s packaging operation, the pump supplier determined that the fault for the improperly filled packets lay with the lobe pump. When the rotary lobe pump would wear, the operators had to adjust the variable frequency drive (VFD) to maintain the proper weight that was being dispensed. However, even after adjusting the VFD, the pumps would continue to wear, and they still could not maintain the proper weights. The performance of the lobe pumps had disintegrated so badly at one point that the rejected packets from the filling line were as much as 24 grams over or underweight. This meant that they were more than 4/5 ounce above or below the required 6- or 9-ounce volume.

Filling a Need

As a solution to the facility’s packaging problems, the pump supplier recommended using an eccentric disc pump. With an eccentric disc pump, no adjustments are required because the pumps are self-compensating, so the VFD does not have to be changed. These pumps can also process 1-centipoise to 10,000-centipoise products without altering the pump speed and still have the same flow rate. After replacing its failing lobe pump, this food processor significantly reduced its product loss and improved profitability. These eccentric disc pumps also feature a sealless design that protects against product losses and leaks. The eccentric movement of the pump makes it highly energy efficient and capable of moving solids up to ¼ inch (6.35 millimeters) in size without pump damage. The design also ensures constant flow rates and safe shear-sensitive product handling. These pumps have a shear rate of sec1 = 0.9 rpm, a clearance of just 1/16 inch (0.157 centimeter), the capability of handling viscosities up to 10,000 centipoise, working pressures to 130 psi (9 bar), flow capacities from less than 1 gallon per minute to 158 gallons per minute (3 liters per minute to 598 liters per minute) and the ability to handle operating temperatures up to 212 F (100 C) with a standard model and 302 F (150 C) with a high-temperature model. For maintenance, the eccentric disc pump offers a clean-in-place design with no bypass valve or mechanical seal required. This means that the pump does not lose volumetric performance because of porting—a common operational flaw of lobe pumps—and it does not need to be bypassed to clean-in-place. When cleaning in place, pressure is simply introduced to the back of the eccentric disc through the pumping chamber. When the flush pressure overcomes the spring, the disc moves away from the cylinder, allowing the cleaning solution to pass through the pumping chamber. This clean-in-place capability allows the pumps to deliver maximum operational flexibility. The food processing facility installed its first eccentric disc pump in July 2011 and improved results were experienced immediately. The pump provides consistent flow that is not affected by wear. “As soon as we installed the eccentric disc pump, we were down to under 2 or 3 percent product loss for over or underweight pouches during an eight-hour shift,” said the production manager. “We don’t need to throw away packets anymore.” While a 24-gram weight fluctuation was experienced with the lobe pump, the production manager noted that the eccentric disc pump reduced that by 60 percent. “An 8- or 9-gram fluctuation is not a big deal and is a tolerance that we can live with,” said the production manager. “A fluctuation of 22 to 24 grams? That causes us to throw away a lot of sauces that are otherwise perfectly good.”

Conclusion

The production manager has been so pleased with the performance of the pump since its installation that he plans to experiment with it when handling products of higher viscosities. “Besides saving money and time and reducing the amount of wasted product, I can say I highly recommend the pump. It is better than any other pump we’ve used,” said the production manager.