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subject: Pressure Sand Filter Specification [print this page]

The principal of sand media filtrationis quite straightforward.

The irrigation source water is pressurized and introduced into the top of

the media tanks. A diffusion plate in the top throat of the tank serves to

reduce water velocity and distribute the water evenly across the top of

the media bed. The media bed is a layer of size-graded crushed silica

sand about 16 in depth. The contaminates in the water are captured in

the media bed and filtered water passes into the discharge manifold at

the bottom of the tanks.

Filtration Mode

sand media filtration are effective at filtering both organic and inorganic

contaminants. The large size and three-dimensional nature of a media

bed provides more surface area and has greater holding capacity than

many other types of filters. Determining filter capacity and understanding the backwash function (cleaning) of your system are among the

most important aspects of successful filtration. These operations and

more will be covered in the following pages.

The key to superior media filtration is the effective removal of the

captured contaminates from the media bed, commonly referred to as

backwashing. Located in the bottom of every Flow-Guard Media Filter

is a highly engineered underdrain system that is designed to perform

two functions. First it must not allow any media sand to pass through

the filters and into the

irrigation system.

Second, during the

backwash operation it

must allow the flushwater to be evenly

distributed throughout

the entire media bed,

with no pockets or

dead spots. This

insures that the media

is lifted and uniformly

rinsed free of contaminants in an efficient

manner.

The Flow-Guard underdrain is made up of a series of stainless steel

wedgewire elements attached to a stainless steel spoke system that

covers the entire bottom of the tank. The large spoke system allows for

a better distribution of the backwash water to the individual wedgewire

elements. The wedgewire is effective in preventing media from entering

the irrigation system and by design does not get obstructed with media.

Covering the wedgewire elements is a layer of gravel. The purpose of

the gravel is to deflect the high-velocity backwash water and create a

very uniform flow, capable of gently lifting the media in the most

efficient manner possible. Efficient backwashing results in cleaner

media sand and shorter backwash cycles.

by: Shubham Inc.

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