Or. Admin. R. 340-073-0041 - Filter Fabric
Except as otherwise allowed by the department, filter fabric used as a barrier between the lower lens of drain media and the medium sand in a conventional sand filter system must meet the following specifications:
(1) Material synthetic
fabric, either spunbonded or woven.
(2) Burst strength not less than 25
psi.
(3) Air permeability not less
than 500 cfm per sq. ft.
(4) Water
flow rate not less than 500 gpm per sq. ft. at 3 inches of head.
(5) Hydrophilic surface reaction to
water.
(6) Equivalent opening size
of 70 to 100 sieve.
(7) Chemical
properties:
(a) Nonbiodegradable.
(b) Resistant to acids and alkalies within a
pH range of 4 to 10.
(c) Resistant
to common solvents.
Notes
Stat. Auth.: ORS 454.625 & 468.020
Stats. Implemented: ORS 454.615
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