Method of washing an upflow filter and filter bed employed in said filter
CA 2090339 C · Owner: Kim, Annabelle · Inventors: Kim, Annabelle; Roberts, R. Lee
Overview
Its claims, description and drawings are in the Canadian Patents Database.
Open the CIPO recordAbstract From the Canadian patent
A method of washing an upflow filter (12) between service runs employs a filter bed (26) having a non-buoyant particulate filter layer (56) through which influent to be filtered is directed in an upward direction and through, which liquid employed in the washing operation is directed in an upflow direction. A two-stage washing operation includes the steps of first directing a combination of air and liquid in an upflow direction through the filter layer (56) with the velocity of the liquid being less than the minimum fluidization velocity of the filter layer (56) for disrupting, only some floc retained in the filter layer during a previous service run, and thereafter directing only liquid in …
Read the whole patent
Listed from its CIPO record in Patent Yard's archive of Canadian patents past their term. Its claims, description and drawings are in the CIPO record and on Google Patents, and the Claude kit works from them.
Why it's free to use
- Filed August 23, 1991 and granted July 2, 2002. A Canadian patent filed from October 1, 1989 lasts 20 years from filing, so its term ended August 23, 2011.
- A certificate of supplementary protection adds at most two years for a drug, so even that would have ended by August 23, 2013.
- We check Canadian rights only. A patent in its family in another country could still be in force: check its family on Google Patents.
Timeline
Timeline From CIPO dates
Sources & verification
Official CIPO records
Everything on this page comes from the CIPO record linked above. Contains information licensed under the Open Government Licence – Canada.