Fitted to the washwater infeed, the Bollfilter 6.19 system removes particulates to ensure efficient performance of washwater booster pumps, as well as keeping down stream nozzles free from blockages. As a practical alternative to an automatic filter with separate backflush pump, the company says that the 6.19 option is neater, uses less energy and is lower cost to install.

The 6.19 Filter uses a backflushing principle that operates without the need for high internal pressure or mechanical scrapers to force debris through the screen. A small amount of the high pressure booster pump flow is fed into the top of the filter during the cleaning cycle to create the necessary velocity on the elements when the backflush valve is opened for highly effective filtration.

Bollfilter adds that the flow splits evenly between the Wedge wire elements and travels through the top and bottom of each one. This evenly deposits the debris along the entire length of each element making use of all of the filtration area. The filter has typically between 12 and 40 elements and the cleaning cycle only takes 20 to 30 seconds. Each element is cleaned individually which means the filter remains in service at all times.

In the backflushing process, the filter operates with two valves open: one to allow the pressured liquid into the filter and the other to allow the dirty liquid to waste. The high velocity in the filter element creates a cross-flow backflushing which draws filtered liquid back through the elements to remove the debris efficiently over the entire length of the element. The filter uses approximately 15 litres of liquid from the outlet of the booster pumps every times it backflushes as most of the required flow is reversed across the elements prior to the pumps. This would typically be every one or two hours depending on the solids loading.

For quick and convenient installation, Bollfilter adds that the complete system including filters, pumps and control panel can be supplied on a single skid-mounted module.