Filterability Index Apparatus .
Specification of Filter Ability Index Unit
consists of a metal framework supporting a 1.5 liter vessel connected
by transparent tubing to a 60mm high filter unit.
- A 0.5m water manometer measures head loss across the filter.
- Test filter cell diameter: 38mm.
Description of Filter Ability Index Unit
use of deep beds of porous granular media to filter liquids to improve
their clarity is widespread in municipal and industrial practice.
Predominant is the filtration of drinking water and industrial water,
although the filtration of sewage as a tertiary stage of treatment is
increasing. Other liquids are filtered through granular media in the
processing of beverages and food products for example.
- A simple
measure of whether the liquid is filterable is useful to enable
assessment of filtration as an appropriate process, if so what type of
pre-treatment and filter media are required. Although the normal methods
of chemical and physical analysis such as suspended solids content,
turbidity, color etc. may, with experience, indicate whether a
suspension is filterable, they give no direct measure of this property.
number of measures of filter ability have been proposed, using woven
micromesh, lint pads or membrane filters, which have application where
these materials represent, or are identical to, the filter media to be
used. However none of them is representative of porous granular filter
media, such as sand, consequently they are not applicable to deep bed
- The Filter ability Index Unit utilizes a bed of
granular material, normally sand, which can be chosen by the
investigator to suit his own purposes. The measurements taken with this
apparatus enable a filter ability number to be calculated which has
significance in deep bed filter performance.
- The Filter ability
Index Unit is not intended for filter design purposes. That requires
pilot filter column equipment such as the Deep Bed Filter Column.
However preliminary assessment of pre-treatment processes, and possible
filter media with the Filter ability Index Unit will reduce the amount
of testing required with pilot filter columns