SubscribeMaking 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 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."
UK marketing manager at Watson-Marlow Bredel, Mike Sullivan, says: "Sealed Air prints onto security bags which hold cash in transit, confidential documents and examination papers. It's a highly competitive market so they have to be able to ensure clear, positive identification and a consistently high standard of printing is essential. We measure the success of our range of pumps by customer satisfaction which stems from the long-term reliability, ease of use and durability of our products."
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.
Bill Wyman cites other practical benefits: "When we are busy, life can be hectic and printers are not always as gentle with equipment as manufacturers might like. The Watson-Marlow Bredel pumps can withstand a surprising amount of rough treatment. They are very easy to maintain and we can wash them down as often as necessary. Downtime is kept to a minimum which is particularly important in our industry."
The 14 pumps installed at Sealed Air are single channel 621F/R peristaltic pumps running at 77 rev/min with an estimated output of 1.5 litres/min of ink.