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TECHNOLOGY - TANK GAUGING
Portable liquid-level gauge for ballast tanks
Mitsui OSK Line (MOL) and
Musashino Co have jointly
developed what they claim is
the word’s first portable liquidlevel
gauge for vessels’ ballast
tanks.
The gauge measures the level of ballast water
(seawater) in a tank by dropping a portable
measuring tube into the ballast tank’s
sounding tube. A sensor detects air pressure
changes in the tube and quickly measures the
ballast water level.
Conventional measurement using a
sounding tape is complex and timeconsuming,
requiring several crew members,
MOL said. Use of this new liquid-level
gauge makes it quick and easy to check the
levels of many ballast tanks, improving
efficiency and enhancing the safety of
loading/discharging operations, the
company said.
Vessels add seawater to their ballast tanks
when discharging cargo and pump it out when
loading cargo. This helps to control the hull’s
trim to help ensure its stability. To prevent air
from entering the ballast pump during the
final stages of discharging ballast water, it is
essential to measure the level of ballast water
remaining in the tank.
Liquid level gauge characteristics -
(1) Seafarers can easily carry the gauge’s
main unit thanks to its compact size
Kongsberg’s answer to tank gauging
Last June, Kongsberg Maritime
presented an updated version of
its K-Gauge system.
The system is now fitted with a GL-300 tank
monitoring solution, which has been fully
approved by all of the major class societies. It
is claimed to be lightweight and easy
to install.
Kongsberg said that it offers increased
reliability, accuracy and durability over
already existing tank monitoring systems. This
was made possible through a range of new
sensors designed by the in-house sensor
technology unit, Kongsberg said.
Speaking at the launch, project manager
Borge Havard said; “We have been developing
radar tank gauging solutions for over 25 years
amd have employed our technical expertise
and application experience to develop our
most accurate, reliable and durable solution to
date. We have had a pilot installation on board
a chemical/oil tanker since September 2008
and reports from the customer are that
everything is working perfectly.”
GL-300 is fully integrated with the K-
Gauge tank management and K-Chief
automation systems, sharing operator stations
and I/O units for other cargo instrumentation.
It is a modular solution based on a new,
what is claimed to be a highly accurate radar
tank gauge, cargo temperature unit and a
signal processing unit centrally located for
each tank.
In addition, a pressure sensor is fully
integrated in the radar tank gauge to reduce
cabling and simplify installation. The modular
concept enables the simple design of custom
solutions and supports ease of maintenance
and trouble shooting, Kongsberg said.
The company also said that the radar tank
gauge drew its high accuracy and durability
from the offset parabolic antenna design,
which is claimed to be capable of
withstanding the harsh tank environment
(35 cm wide x 33 cm high x 23 cm deep)
and light weight (about 5 kg).
(2) It takes only 10 to 15 seconds to measure
the liquid level in each ballast tank.
(3) It is compatible with most vessel types as
the gauge uses the vessel’s air compressor
system. The gauge’s main unit can be
connected with the air hose with a onetouch
system.
(4) The pressure sensor automatically adjusts
for changes in temperature and
atmospheric pressure.
(5) A 9V battery is used for power source of
the main unit. Measurements are displayed
in digital format. It also has an auto-off
function to maximise battery life.
and is resistant to condensation and cargo
deposit problems.
The antenna radiates a high frequency
narrow beam, which makes it easy to position
in the tank. By June last year, the company
had delivered more than 4,000 units of the
previous generation systems, which have had
the same antenna design since 2005.
It is applicable to most liquid cargoes,
including crude oil and chemicals across the
entire temperature range and is suitable for
sockets having an inner diameter of 200 mm
or larger (JIS flange). It is claimed to
lightweight and has been designed to offer the
easiest of installation and maintenance,
compared with other designs currently on
the market.
Kongsberg said that several design
elements made this claim possible, from the
inspection hatch on the GLA-300 radar tank
gauge to the minimisation of cabling across
the entire system.
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46
TANKEROperator January/February 2010