Ultrapure Water System Moving Hood Filter Flushing Process

Washing Process: When a filter cell needs washing, the washing hood 10 is moved by the gantry crane 12 to the top of that filter cell and seals the top of the filter cell. Simultaneously, air is extracted from the drainage siphon pipe 11 using an air extraction device. When the vacuum level in the drainage siphon pipe reaches a certain value, a siphon is formed (hence the name "siphon type" for this type of washing hood), and washing begins. The washing water, filtered from the remaining filter cells, enters the filter cell through the low-resistance water distribution system distribution chamber 5 and distribution chamber 4. After passing through the support layer and filter media layer, the washing wastewater is discharged into the drainage ditch 6 through the drainage siphon pipe 11. The difference between the water level Z2 at the effluent weir crest and the water level Z3 in the drainage ditch is the washing head, typically 1.0–1.2 m. When there are many filter cells, the filter group can continue to supply water to the clear water tank during the washing of one filter cell. After washing is complete, the washing hood moves to the next filter cell, and the next filter cell is then washed.