TRACK 



PLAN 



36.27m. 



ELEVATION 



Figure 7. — Track arrangement of traveling screen. 



operated with a wire-cloth screen. With ad- 

 vances in design and fabrication of nylon net- 

 ting, however, we considered it necessary to 

 test its durability, head loss, and the relation 

 of mesh size to efficiency of screening fish. 

 Without exception, each of the nylon net ma- 

 terials tested demonstrated an unusual ability 

 to withstand physical and chemical deteriora- 

 tion. 



On the basis of the success of these tests, 

 we selected a 12.7-mm. stretched nylon net 

 (No. 50), manufactured by the Linen Thread 

 Company of Blue Mountain, Ala.* The netting 

 (twine diameter, 1.02 mm.) had an effective 

 open area of 72 percent. To attach the net 

 panels to the stiff-legs, a bulblike border was 

 formed along all four sides of each net. This 

 border in turn was fitted into specially de- 

 signed slots on the vertical stiff-legs and 

 horizontal connector tubes (fig. 10); about 5 

 minutes were required to replace a net panel. 



An open space of about 7.62 cm. was inten- 

 tionally left between the concrete sill on the 

 canal floor and the bottom of the traveling 

 screen to prevent contact between the bottom 

 of the stiff-legs and netting. To prevent fish 



'Trade names referred to In this publication do not 

 Imply endorsement of commercial products by the Bureau 

 of Commercial Fisheries. 



from passing through this opening, a sealing 

 system was provided by vertical attachment of 

 a flexible 15-gage wire-cloth screen (used 

 normally as conveyor belting) to the underside 

 of each panel. During operation of the panel, 

 the wire-cloth screen effectively sealed the 

 opening, remained clear of moss and grass, 

 and provided the flexibility and durability 

 needed. 



Bypass Design 



A 1.8-m. deep and 6l-cm. wide bypass was 

 placed in line with the direction of screen 

 travel to accommodate the screen as it traveled 

 up and out of the water. When traveling screens 

 are not raised out of the water (models VI and 

 VU), the bypass can be placed in line with the 

 direction of waterflow as with louvers. Flow 

 within the bypass was controlled with an elec- 

 trically operated watefgate. 



OPERATION OF TRAVELING SCREEN 



We evaluated the efficiency of the traveling 

 screen in five specific areas: (1) rate of 

 screen travel, (2) head loss, (3) deflection 

 efficiency, (4) self-cleaning capabilities, and 

 (5) bypass. 



11 



