US4995990A — Air and water distribution conduit

Claim 1

Independent Claim 150 words

In a granular media filter including an underdrain system comprising perforated lateral conduits arranged for the distribution of air and water for scouring and backwashing of the filter, each conduit being in the form of a single linear conduit containing two or morw separate axially parallel ducts separated by one or more internal wall(s), the improvement consisting in that each duct has an external wall in common with its conduit, which external wall is provided with axially spaced apertures for emission of water or air, said axially spaced apertures located in an upper position in at least one of the ducts projecting downwards into the duct as an inwardly extended duct, and in that in each conduit at least one duct is arranged for the distribution of air and at least one duct is arranged for the distribution of water, there being no air and water intercommunication between the ducts.

Claim 2

Dependent Claim 150 words

In a granular media filter including an underdrain system comprising perforated lateral conduits arranged for the distribution of air and water for scouring and backwashing of the filter, each conduit being in the form of a single linear conduit containing two or morw separate axially parallel ducts separated by one or more internal wall(s), the improvement consisting in that each duct has an external wall in common with its conduit, which external wall is provided with axially spaced apertures for emission of water or air, said axially spaced apertures located in an upper position in at least one of the ducts projecting downwards into the duct as an inwardly extended duct, and in that in each conduit at least one duct is arranged for the distribution of air and at least one duct is arranged for the distribution of water, there being no air and water intercommunication between the ducts.

Claim 3

Dependent Claim 23 words

The filter according to claim 1 in which the two or more separate ducts are located side-by-side with the internal wall(s) substantially vertical.

Claim 4

Dependent Claim 46 words

The filter of claim 2, in which the upper surface of each conduit is provided with upwardly extending supply collars, the apertures opening into said collars such that each collar can communicate with said two or more ducts whereby it can receive both air and water.

Claim 5

Dependent Claim 26 words

The filter system of claim 3, in which the underdrain system is encased in concrete to provide a filter floor from which the supply collars protrude.

Claim 6

Dependent Claim 21 words

The filter of claim 3 in which at least one of the apertures and the collars are provided with strainer means.

Claim 7

Dependent Claim 34 words

The filter of claim 1 in which the external wall of the duct for air distribution is provided with at least one additional aperture at a lower level than the said axially spaced apertures.

Claim 8

Dependent Claim 16 words

The filter of claim 1 in which each conduit is formed from a one piece extrusion.

Claim 9

Dependent Claim 12 words

The filter of claim 1 having conduits of generally circular cross section.

Claim 10

Independent Claim 165 words

A method of supplying a combined air scour and water backwash to a granular media filter by incorporating therein and using an underdrain system comprising perforated lateral conduits arranged for the distribution of air and water for scouring and backwashing of the filter, each conduit being in the form of a single linear conduit containing two or more separate axially parallel ducts separated by one or more internal wall(s), the improvement consisting in that each duct has an external wall in common with its conduit, which external wall is provided with axially spaced apertures for emission of water or air, said axially spaced apertures located in an upper position in at least one of the ducts projecting downwards into the duct as an inwardly extended duct, and in that in each conduit at least one duct is arranged for the distribution of air and at least one duct is arranged for the distribution of water, there being no air and water intercommunication between the ducts.

Claim 11

Independent Claim 165 words

A method of supplying a combined air scour and water backwash to a granular media filter by incorporating therein and using an underdrain system comprising perforated lateral conduits arranged for the distribution of air and water for scouring and backwashing of the filter, each conduit being in the form of a single linear conduit containing two or more separate axially parallel ducts separated by one or more internal wall(s), the improvement consisting in that each duct has an external wall in common with its conduit, which external wall is provided with axially spaced apertures for emission of water or air, said axially spaced apertures located in an upper position in at least one of the ducts projecting downwards into the duct as an inwardly extended duct, and in that in each conduit at least one duct is arranged for the distribution of air and at least one duct is arranged for the distribution of water, there being no air and water intercommunication between the ducts.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1994-02-25	1994-08-27	1995-02-26	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1998-02-25	1998-08-27	1999-02-26	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2002-02-25	2002-08-27	2003-02-26	$7700.00	Window Closed / Lapsed

Air and water distribution conduit

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