MULVFS Operations

The MULVFS has 12 pump/filtration units, each capable of filtering up to 16,000 L of seawater through a filter series consisting of 51 um polyester mesh and a pair of 1 um quartz fiber filters. Each of the pumps also processes 2500 L through adsorber cartridges designed to trap dissolved natural uranium series radionuclides (particularly Th-234/U-238) present in seawater. Another flow channel allows processing of 100-200 L through specialized adsorber/filter combinations.

The 12 light-weight/low-drag pumps are operated simultaneously in profile from the surface to 1000 m depths using ship-generated 440VAC 3-phase power. This is accomplished via an uniquely engineered 1000 m long electromecanical cable and cable handling system. Depth and flowrate information is transmitted in real time from several pump units during operation.

Typical station time is 7-8 hours including deployment and recovery. Operations require a minimum of 2 people at sea. The system is designed to be tolerant of winter time conditions. Images: Top left. Installation setup for stern deployment aboard CCGS Tully. Top right, MULVFS pumps secured and ready for station, details of vertical sampling capability, and pump units. Bottom: Left hand side. MULVFS Winch installed for deployment using the hydroboom of R/V Revelle.

Details of MULVFS components and operations requirements

MULVFS Pumps and Cable Handling System MULVFS System Detail


Mechanical. Like all over the side operations, equipment and system components come under loads due to the action of ship motion and seas. Personnel must minimize time beneath working sheaves and the line of the electromechanical cable leading from the winch to the equipment deployed over the side or stern of the ship. Loads on these systems can be thousands of pounds. You can imagine that a hard hat will not help much if you are hit from above by a 30" diameter sheave like the one we use.

Hydraulic systems are used to drive the winch and to aid spooling of wire onto the winch. Such systems have been engineered to maximize safety but personnel must also avoid these systems while they are working.

Electrical. 440 V 3 phase electricity is used to power the Winch and Level wind of the MULVFS during its deployment and recovery. The connection of this equipment to the ship's power supply must be done under supervison of qualified ship's personnel.

When MULVFS is deployed and operating. Power is fed from the ship's supply via an electrical cable from LBNL's control equipment located in a dry area of the ship to the winch located on deck. Between the ship's power supply and LBNL controls there is a mechanical lock out breaker and an isolation transformer. The 'lock out' breaker must be off and 'locked out' prior to connecting or diconnecting the deck cable at the winch.

The mechanical breaker must be off and locked out during all deployment and recovery operations and when the deck cable is physically disconnected from the winch.

The system is protected during operation (while samples are collected) through redundant use of an isolation monitor/drop out relay and computer controlled relays. Personnel are advised to stay away from the winch and wire during operations.

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