The coating clay contains 55-75% solids, including kaolin, marble, carbonates and titanium oxide, and dries
instantly. It was therefore critical that the pump chosen should prevent moisture loss, and have a gentle action to avoid shearing and damage to the pumped mixture.
Mono NOV’s distrtibutor recommended vertically mounted pumps from the Mono industrial range. These have been
installed so that the seal area does not come into contact with the coating clay mixture; flushing is therefore unnecessary and there is no chance of the coating being diluted. The pumps stainless steel body, chrome-oxide coated, stainless steel rotor and nitrile rubber stator were chosen to avoid possible contamination of the clay coating mixture.
Any risk of contamination is further reduced by Mono’s unique Flexishaft, which links the drive shaft to the helical rotor. This device has no wearing parts, making joint lubrication unnecessary so avoiding product contamination. The simplicity of the design reduces the number of parts in the pumps, making them easy to dismantle and reassemble. Increased reliability lengthens the intervals between routine maintenance.
The three pumps at Frövi operate at speeds of between 160 and 250rpm at 1.5 bar pressure, delivering the
coating at rates of up to 110m3/h. The mill produces around 250,000 tons of coated board each year, primarily for the leading packaging manufacturer of juice and milk cartons.
The pumps have been running continuously since autumn 1994 without any problems. During this period loss
of production due to coating mixture dilution, has dropped to 0.4%.