painted on the outside of the housing corresponding to the 

 position of the reed switch inside. A time-delay relay was 

 incorporated into the circuitry so that it was necessary to hold 

 the magnet near the target for 5 seconds (adjustable between 1-30 

 seconds) before the pump started, to avoid accidental starts. A 

 3 1/2 " diameter Lexan porthole on the side of the housing 

 allowed viewing of a control panel containing indicator lights 

 showing initial switch actuation, time-delay, and pump operation, 

 and an LED digital clock showing pump running time in seconds. A 

 digital display turbine-type flow meter was also incorporated but 

 was not used in these initial experiments. 



The intake pump is connected by rubber hose to the sampling 

 flume, with the outlet connected to the filter assembly by PVC 

 pipe. The filter assembly was similar to the JSL unit but 

 fabricated of welded PVC instead of aluminum. A bronze non- 

 return valve between pump and filter prevents back flow of water 

 and fluff from the filter after the pump is switched off. 



The welded end of the housing contains a pressure relief 

 valve set at 2 psi, to prevent excessive pressure build-up in the 

 housing due to either leakage at depth or severe temperature 

 differences and consequent danger upon opening the housing. 

 There is also an 0-ringed plug providing access to a vent in the 

 battery housing, and a throughhull penetrator from the batteries 

 to a connector for charging and/or monitoring of battery 

 condition. The batteries have sufficient capacity to run the 

 pump for approximately 10 min but recharging is performed 

 routinely after each dive, a process requiring 10-15 min. 

 During the charging the housing access plug is removed and the 

 battery housing vent unscrewed to prevent build-up of hydrogen 

 and potential explosion in combination with brush arcing from the 

 DC motor. 



The tubular housing is supported on two skids, 24" apart, 

 running the length of the housing and adjustable vertically so 

 that the weight on, and thus penetration of, the flume could be 

 varied. The complete sampler unit weighs approximately 70 lb in 

 air, but, with the addition of two small aluminum tubular 

 buoyancy tanks, only 1-2 lb in saltwater, allowing it to be 

 easily maneuvered and emplaced. A multihole mounting plate on 

 top of the housing allows for variation of the suspension point 

 from the sub in order to experiment with different emplacement 

 attitudes. Operation depth limit for the complete device is 

 1,000 ft, with a designed failure depth of 3,000 ft. 



Deployment of the FLS 



There are a variety of problems associated with gently 

 emplacing the FLS into a soft and easily resuspendable sediment, 

 with a need for vertical positioning accuracy in areas of 

 occasionally high turbidity. The solutions to these problems are 

 different for the various dive systems used to date. 



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