DRUM SCREENS 



Figure 1. — Map showing location of Stanfield traveling screen. 



Figure 2. — Plan view of Stanfield traveling screen. 



Water load on screen--34 kg. per square 



meter (7 lb. per square foot) 

 Water velocity-- 1.8 m. per second (6 ft. 



per second) 



Uniform live load on structure-- 146 kg, per 

 meter (100 lb. per foot). Water and wind-drag 

 loads on screen elements were determined by- 

 varying water and air velocities and screen 

 travel speeds. 



The screen was placed at a relatively small 

 angle (20°) to the direction of flow (fig. 2) to 



reduce the water pressure, or loading, on 

 the screen and to prevent impingennent of 

 small coho salmon (minimum length, 37 mm.) 

 that were used to test the efficiency of the 

 deflection system. The fish approached the 

 screen tail first and were deflected to one side 

 when the water velocity was not too great. They 

 headed generally into the flow and were 

 carried downstream by the force of velocity. 

 When the water velocity exceeded their swim- 

 ming speed, or was faster than 46 cm.p.s. 

 (centimeters per second), the salmon positioned 

 themselves at an angle of 90° to the face of 

 the screen. In this position, somewhat broad- 

 side to flow, they needed to swim at only 26 

 cm.p.s. to avoid impingement. Had the screen 

 been placed at a 30° angle to flow with an 

 approach velocity of 107 cm.p.s., the fish would 

 have had to swim at about 40 cm.p.s. to remain 

 free of the screen. Selection of the 20° angle, 

 in this situation; made it easier for the fish 

 to orient to the face of the screen. 



Structural Design 



The structural portion of the screen pro- 

 vides the support system for the traveling or 



