Providing Solutions in Filtration & Screening since 1977
Champion Filters Mfg. Co.
Automatic Valveless Gravity Filters
Sand, granular media or multimedia bed filtration are generally applied for removal of suspended solids in the 5 to 50mg/l range where an effluent of less than 1 JTU is required. Champion sand filters have been used in municipal and industrial water plants where the clarifier contains 5 to 20 mg/l of suspended solids.
Champion granular media filters are also used to filter cooling water side streams to reduce suspended solids buildup where effluent clarity is not critical. Granular media can handle suspended solids up to 1000mg/l and provide about 95% removal efficiency.
Champion uses several types of filter media like silica sand, crushed anthracite etc. The general path to coarse to fine filtration is up flow filtration. Water is applied into the bottom of the bed. Solids can penetrate the coarser grain medium resulting in deep bed filtration. Backwashing occurs in the same direction as the filtration.
Champion Multimedia Filter Beds :
Multimedia filter beds are basically a stacked media bed or two layers designed to provide coarse to fine filtration in down flow pattern. The two materials have different grain sizes and different specific gravities. Generally ground anthracite is used in conjunction with silica sand. Depending on the quality of effluent desired, garnet is also used.
Champion uses multimedia filter beds in Automatic Valve less gravity filters.
These filters are completely automatic.
There are no pumps or valves.
No operator is required for supervising the filter.
The filter would backwash itself whenever the dirt load exceeds the set limits.
Champion Automatic Valveless Gravity Filters also known as VAG , AGF , VAGF filters use the gradual increase of head loss across the filter to actuate the backwash of filter bed. These filters are known as automatic valveless gravity filters.
Sand is used as filtering media and works on the principal of gravity filtration without any valve, pilot mechanisms, rate controllers, gauges and air compressors. There are two compartments, one for filtering section and other for storage of wash water.
During normal operation water gets filtered while traveling across the sand bed. During filtration suspended solids gets accumulated in the filter bed and differential pressure start increasing which causes the water level to rise in the backwash pipe. When the water level reaches the top of the loop, siphon action starts and backwash begins. Wash water flows from the storage compartment through the sand bed and is discharged through the back wash pipe. A siphon breaker ends the wash cycle.
Design parameters :
Effluent quality : First the quality of effluent desired is considered to design the filter. The selection of filter media for an effluent quality of 0.1 JTU is different than what is required for 1.0 JTU.
Flow rate : Flow rate through the filter is critical, since it limits the throughout put and dictates the number of filters required. Generally as flow rate increases, penetration into the filter increases.
Water Temperature : Water temperature affects the filter performance due to viscosity. Filtration is better at higher temperature whereas backwashing is better with cold water as increased viscosity more effectively scours the filter bed to remove solids.
As the media starts to load with solids, the net velocity at a given flow rate increases until shear forces tear the solids apart and they escape into the effluent. All manual backwash filters have to be backwashed before this happens hence they need to be monitored.
The major applications of these filter are for raw water clarification, site stream filtration of cooling tower etc i.e. mainly for low turbidity applications.