Sand and gravel filters are applied in surface water, open water, circulating water and other filtration systems. They are highly efficient, energy-saving, environmentally friendly and green fully automatic water filtration equipment. The filter material uses natural quartz sand, and the cleaning method adopts internal backwashing, which is energy-saving and water-saving. The agricultural drip irrigation sand and gravel filter is a type of filter that uses quartz sand or water distributors to form a sand bed as the filter carrier for deep planar filtration, and is often used for primary filtration. It mainly uses natural quartz sand as the filter material for filtration. Its sand bed is three-dimensional filtration and has a strong ability to intercept impurities. Among all types of filters, sand and gravel filters are the most effective for treating organic and inorganic impurities in water. These filters have a strong ability to filter out and retain impurities and do not require continuous water supply. When the organic matter content in water exceeds 10mg/l, regardless of the inorganic matter content, a sand and gravel filter should be selected.

When the system is in the backwashing state, the filtration continues. Among them, the standard unit sand tank that needs to stop backwashing does not stop filtering, while the other standard unit sand tanks in the system are still filtering. The filtered clean water is partially used for backwashing the standard unit sand tank, while the rest is still sent to the user. Backwash wastewater is discharged through the backwash drain port of the hydraulic valve. In the fully automatic high-efficiency filtration system of the high-speed sand cylinder, the special water collector design enables the fillers to rub against each other, maximizing the backwashing efficiency, reducing the required backwashing water (clean water), and at the same time, there is no material leakage during backwashing.

The backwashing of one standard unit sand tank takes 2 minutes. After the backwashing is completed, the internal pressure head loss of the standard unit sand tank decreases to a reasonable range. The constant pressure installation gives a recovery signal, and the hydraulic valve returns to the filtration state. The next standard unit sand tank is ready to enter the backwashing state.