1) Gravel Filter: used for primary filtration of water from reservoirs, dams, open canals,rivers,sewage water.

Gravel filter is one of Medium Filters. It is always used for primary filtration of water from reservoirs, dams, open canals, rivers, sewage water, and other contaminated water.

Sand bed is three dimensional which has strong ability of interception filth .It is a ideal equipment to clearance the filth in agriculture micro-irrigation system .Have a strong ability to filter out and retention impurity. And at the same time, it can supply water continuously.

The shape of the filter tank is usually cylindrical. And it allowed to deposition more thickness impurity than screen filters and segmented filter.

We can use the sand filter singly, back flushing manually. Usually there are two or more tanks which are combined together according to the flow rate of the irrigation system. We can do the back flushing manually or automatically by a controller and some electromagnetic valves.

Model	Inlet	Flow rate (m³/h)	Model	Inlet	Flow rate (m³/h)
HWSF2001	2	20	HWSF2802	4	75
HWSF1402	2	20	HWSF3002	4	85
HWSF2401	3	30	HWSF3202	6	100
HWSF2002	3	40	HWSF2603	6	100
HWSF2402	4	55	HWSF2803	6	115
HWSF2602	4	65	HWSF3602	6	125