108. Both the hydraulic and sand- trapping efficiency tests indicate 

 that the C nozzle has hydraulic and sand- trapping efficiencies closest to 

 unity among the 23 streamer trap nozzles examined in this experiment program. 



109. Hydraulic efficiencies determined for the H-S sampler confirm 

 earlier results appearing in the literature (Druffel et al . 1976). However, 

 sand- trapping efficiencies for the H-S sampler were higher than the 150 to 175 

 percent that has been stated in the literature for sand- sized material (Helley 

 and Smith 1971, Emmett 1980). Results from the present experiment program 

 reinforce previous studies recommending that the H-S sampler not be used for 

 material finer than 0.25 mm and at sites where material can also be transport- 

 ed in suspension (Emmett 1980). Because of its self -burying characteristic, 

 sediment -flow conditions in which the H-S sampler can be used may be very 

 limited. 



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