128 



D. S. MANN, D. W. McLEESE, AND L. R. DAY 



^TS^?*!!!! 



Figure 4. — Overhead salt-water and compressed-air lines in the basement laboratory. 



Valves and connectors throughout the 

 system are of nontoxic plastic materials, 

 usually rigid PVC but in some cases a 

 blend of styrene acrylonitrile-butadiene 

 copolymer, sold under the trade name 

 Uscolite. 



The most satisfactory valve design used 

 to date in our experience is a ball valve of 

 rigid PVC using soft-seal seat rings of 

 Teflon. This valve does not stick even 

 after prolonged periods in either the open 

 or closed position. Only a quarter turn 

 is required to close the valve. No pressure 

 is needed to effect a tight seal. 



All piping is black or gray to exclude 

 light and thereby inhibit seaweed growth. 

 Differently colored pipes can be used as 



a key or code to the contents and supply 

 points. Fouling by mussel growth and 

 occasional clogging with silt and sand are 

 continuing problems. To reduce clogging 

 and to facilitate cleanout, straight runs of 

 pipe are used wherever possible. Clean- 

 outs (tees instead of 90-degree elbows) and 

 break-away couplings are provided at the 

 ends of straight runs of pipe. Although 

 considerable cleanout is accomplished by 

 flushing, it is sometimes necessary to clear 

 sections of the pipes with mechanical 

 reamers. Numerous shutoff's are located 

 at strategic places to allow partial shut- 

 down to repair, to clean out, or to extend 

 the lines. Wherever possible, pipes and 

 fittings are exposed and readily accessible. 



