Coarse screen is required to remove medium sized floating waste coming with the flow in to a pumping station. EX: Plastic bottles, cans, cloth, plastic bags, napkins, household wastes, weeds, shrubs etc.
There are two major objectives of the coarse screen.
a) To prevent pumps form frequent breakdown by restriction the size of waste material from entering in to pump.
b) To ensure that the efficiency of pumps do not decrease due to chocking of impellor cavity on account of entry of cloth, plastics and other fibrous wastes.
Coarse screen are generally installed with in a pumping station with an isolation gates/stop logs located before and after the screen.
Coarse screen equipments that are commonly employed are:
A. Multi racking bar screens
B. Single on mono racking bar screen (for small size channel)