Washing- River Water for Power Plants 



Sifters on endless chains keep out the rubbish 



A POWER plant cannot use the water 

 from the city mains since that would 

 be too expensive. Instead it cleans 

 the water of a river and pumps that up into 

 the boilers and into the steam-condensers as 

 it is needed. To-day, huge moving screens 

 are used in the larger plants throughout the 

 United States, but only a year or so ago, 

 they were using stationary' screens placed in 

 the supply-pipes which lead from the 

 water. These were very unsatisfactory; 

 for after heaw rain storms, the water 

 would be filled with rubbish. 



In the new form of filter this trouble 

 is done away with. Here the screens 

 are very much like platforms on a 

 traveling-staircase. The water to be 

 cleaned must first pass through the 

 moving screen-sections before reach- 

 ing the supply-pipes. When the 

 rubbish which is carried along reaches 

 the top of the filter, it turns around 

 with it on a large sprocket-wheel and 

 then meets a powerful spra^' coming 

 from behind. It is thus whipped 

 off the filter into a trough of run- 

 ning water, and from thence it 



At right: Diagram showing the 

 details of the device and the course 

 of the water over the screens 



is washed into the down-stream side of 

 the river, out of the way. 



These filters are built in single units 

 which occupy a space six feet wide and 

 about forty feet long. Where the water is 

 let in from the river in channels more than 

 six feet wide, a number of units, forming a 

 battery of filters, must be placed side-by- 

 side. In each unit, the screen-sections are 

 placed close together on two endless steel 

 chains driven bv a small electric motor. 



The screen consists of two strands of 

 chain carrying wire-covered frames 



Each unit is run by a small five-horsepower motor and is cap- 

 able of cleaning sixty-nine million gallons of water per day 



