NBN ISO 9912-4:2021

This document specifies construction requirements and test methods for pressurized granulated
media filters, hereinafter referred to as media filters, intended for operation in agricultural irrigation
systems.
It is applicable to both manual cleaning media filters and automatic self-cleaning media filters, used as
single unit or in batteries (two or more units working in parallel).
This document covers the operation and performance of a media filter, together with all related valves,
back flushing mechanism, underdrains, manifolds and other related accessories necessary for the
operation of the filter.
This document is applicable to three configurations of a filter.
a) An empty filter vessel (tank) housing.
b) A filter vessel filled with media filter material(s), complete with valves, connections, air release
and/or other accessories. This configuration, when connected to and controlled by a flushing
control device, is a complete operating single filter unit, usually positioned as a part of a filtration
station.
c) A filtration station, called “filter battery”.
Annex A provides information on types of irrigation media filters.
Annex B provides information on granulated media.