Pumping water-based inks without foaming

Making the environmentally sound switch from solvent-based to water-based printing inks left Sealed Air Ltd faced with a foaming problem. The solution was to fit Watson-Marlow Bredel peristaltic pumps to replace the diaphragm pumps that were responsible for agitating the ink.

Sealed Air, based in Royston, Hertfordshire, operates three VK presses 24 hours a day, five days a week printing onto security bags. As part of a £250,000 programme of investment to convert its equipment from solvent based to water-based printing inks, it bought 14 Watson-Marlow Bredel 600 Series peristaltic pumps, used to continually feed ink to the presses.

Bill Wyman, print manager at Sealed Air, says: "We switched from solvent-based inks for environmental reasons, but water-based inks tend to foam when agitated and the diaphragm pumps we were using on the original inks weren't capable of consistently delivering the required standard of accuracy when tried for the job.

"We selected Watson-Marlow Bredel pumps after an extensive programme of tests on a variety of pumps including other peristaltics. Not only did the gentle, low shear, roll/squeeze pumping action of the Watson-Marlow Bredel 600 Series ensure that the water-based inks were pumped without foaming, but they had the ability to achieve and sustain a high level of volumetric accuracy as well".

When using Watson-Marlow Bredel peristaltic pumps, changing ink colour by simply flushing the tube element with cleaning fluid is sufficient. Where there is a sharp colour contrast, a simple tube changeover - carried out within minutes - is all that is necessary. With the ink enclosed in the tube and no glands or seals, any risk of leakage or cross contamination is totally eliminated.