Page 32: of Maritime Reporter Magazine (June 1973)

Tank SAPP Develops Inert Gas

Control And Monitoring System

It is now generally accepted that an inert gas system is the most effective method of con- trolling potentially explosive atmospheres in large tankers. However, a tanker fitted with an inoperable system is as dangerous as a com- pletely unprotected ship.

To help control the problem, Tank SAPP— international contracting consultancy in tanker safety and pollution control—has developed a new piece of equipment which monitors and continuously logs the performance of an inert gas system.

During each voyage, the control unit elec- tronically records the main factors of perfor- mance, and the resulting charts are subsequent- ly returned to Tank SAPP's Croydon offices where they are analyzed. The tanker owner is then advised on the performance of the vessel's inert gas system and whether any faults are due to plant inefficiency or faulty crew opera- tion.

If Tank SAPP hold a maintenance contract on the vessel concerned, they will then carry out necessary repairs, servicing or crew train- ing through their network of offices and as- sociates around the world.

During a voyage, the monitoring section of the control system records the following: a. Inert Gas Oxygen Content—Low oxygen content ensures that the atmosphere is never in an explosive condition. b. Scrubber Differential Pressure — This is an indication of the pressure drop between scrubber inlet and outlet. c. Inert Gas Discharge Pressure d. Scrubber Outlet Temperature

From those readings, Tank SAPP can ana- lyze such faults as the buildup of soot or dirt, blockage of the scrubber or internal corrosion.

These faults cannot be seen by the crew, but over a period they can reduce the inert gas system's efficiency or stop it altogether. They can also see whether the pre-set water supplies to the scrubber are maintained for optimum cleaning and cooling. Based on a mimic di- agram concept, the equipment is extremely easy to operate. The complete unit may be in- dependently mounted or incorporated in exist- ing engine room control systems. All com- ponents are manufactured to marine standards.

This control system provides for centralized control with audible and visual indication of the system status. It includes remote operation of fans (including fan isolation valves), scrubber pump and boiler uptake valves. The discharge pressure of inert gas is controlled from the main panel.

The control unit electronically records the main factors of performance, and the resulting charts are subse- quently returned to Tank SAPP's Croydon offices where they are analyzed.

The main control panel comprises an Eldon type TD 362 console topped by an Eldon type

TD 162 desk console. The mimic panel is en- graved on the desk top and incorporates the control switches and pushbuttons, indicating lamps and alarm panel.

The base section houses pneumatic equip- ment electrical relays and connection points.

On top of the desk unit two Eldon type 361 panels are mounted : the right-hand unit houses a multipoint potentiometric recorder, and the left-hand unit houses an indicating pressure controller, a pressure regulator and an auto/ manual controller. This unit can be mounted separately in the cargo control room to allow personnel to control deck main pressure.

Visual and manual alarms are 'fitted to in- dicate the following malfunctions in the sys- tem : high scrubber water level; low scrubber water flow; high scrubber outlet temp; high fan outlet temp; fan failure; low seal water flow; low deck seal water level; high oxygen content; low inert gas pressure, and a cargo tank vacuum.

The first two Tank SAPP control monitor- ing units are 'being installed on the Conoco

Espana and Conoco Britannia. A third has been ordered for installation aboard the Indian vessel Jag Laadki.

Tank SAPP offices in the United States are located at 330 Madison Avenue, New York,

N.Y. 10017, and at 1020 Springfield Avenue,

Mountainside, N.J. 07092.

GILLEN BACKS EVERY JOB ...with over 100 years of . the best in service

WEST END AVENUE, OYSTER BAY, NEW YORK, N.Y. 11771 • 212-895-8110 34 Maritime Reporter/Engineering News