due to a near-hull attachment of most of the system components, 

 5) shipboard calibration facilities for the system's temperature 

 sensors, and 6) in-line ports available for easy incorporation of 

 additional flow stream sensors or samplers (such as the ISCA, as 

 follows, in a "SCANNER" (Submersible Chemical Analyzer) mode in 

 the fashion of Johnson et al., 1986). 



The SIS-3, as shown pictorially in Figure 6, was tested during 

 the 1987 Alvin dives. The manifold portion of the system was 

 designed to fit close under the forward section of the Alvin 

 sphere to keep weight as far aft as possible and to preclude 

 interference with other activities that utilize the basket and 

 manipulators. The flow path was fabricated in a manner to mini- 

 mize contamination and preserve heat between the inlet and the 

 samplers. The tubing, joints, and fittings were made from com- 

 mercially pure titanium, with alumina ceramic liners in the tubing 

 sections. 



The inlet nozzle is free to rotate in two dimensions and is 

 gripped by the T-handle with the manipulator arm. The nozzle is 

 closed on the bottom and slotted on the sides to reduce clogging 

 during the excavating often associated with sampling. The tip of 

 the inlet temperature probe is located directly above the intake 

 slots. The arm, which is extensible and free to rotate, is 

 comprised of two titanium tubes with internal ceramic liners 

 carefully sized to slide together and sealed at the central 

 ceramic joint with a silicone O-ring. The shoulder joint on the 

 manifold is located directly below the port manipulator arm of 

 ALVIN and is also free to rotate in two dimensions. The 100 cm 

 long titanium manifold is lined with 3.1 cm ID ceramic tubing, and 

 is fitted with 8 outlet ports along the sides through which the 

 samples are drawn. The starboard end of the tube is fitted with 

 another temperature probe to monitor manifold temperature. The 

 flow is channeled from the bottom of the end plate of the manifold 

 into a cooling coil to dissipate heat and then to a turbine flow 

 meter for monitoring flow rates. Vinyl tubing connects the flow 

 meter to the main suction pump, which is a rubber impeller driven 

 by a pressure-balanced DC motor. 



Water samples are drawn through sampling ports into one of 

 four possible major samplers on the forward side of the manifold. 

 The tripping mechanism on the samplers is actuated by a small 

 hydraulic cylinder connected to the submersible' s hydraulic 

 system. Two UCSB Gas-Tight samplers are fitted on the aft side of 

 the manifold and are also actuated by hydraulic cylinders. Both 

 of these types of samplers have purge ports on the intake valves 

 that are used to flush the dead volume behind the valve body. A 

 flushing pump, identical in type to the main suction pump, is 

 connected to these ports via a collection manifold. Additionally, 

 two 500 mL polycarbonate syringes fitted with teflon inline filter 



47 



