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Principle of operation

The RTG employs the Frequency Modulated Continuous Wave

(FMCW) principle with dual sweep technology to eliminate

Doppler-effect caused by cargo movement. Frequency sweep

ing microwave signals are emitted from two separate electronic

units and through a common standpipe. The distance (i.e. the

ullage) is derived from the time delay of the reflected signal.

The standpipe is assembled by sections adjusted to match the

total tank height. The pipes have ventilation holes allowing the

vapour pressure inside and outside the pipe to stabilize, thus

allowing the liquid to rise or fall unimpeded in the pipe.

Each pipe section is supplied with flanges prepared with refer

ence markers. The liquid level and the markers are measured

simultaneously, so the system automatically verifies itself at

every measurement. By careful calibration of the pipe sections

length before installation, the positions of the markers are re

corded and stored in the system. By comparing the liquid echo

with the signature plate echo, a continuous auto-calibration of

the measurement is done.

The electronic units in the RTG includes a patented signal

detection method that ensures optimum performance. Com

bined with its superb signal-to-noise ratio, GLA-310/5 offers the

highest measurement reliability and accuracy.

Each electronic unit is connected to a dedicated signal process

ing unit, where the AutroCAL® principle is employed.

RADAR TANK GAUGE FOR GAS CARRIERS

The KONGSBERG Radar Tank Gauge (RTG), GLA-310/5 DUAL is

designed for redundant measurement of level in tanks containing

liquefied gases. Accurate measurement is possible regardless of

the tank amospheric conditions. Flexible design ensure easy

adaptation to LPG (Propane, Butane), LEG (Ethylene, Ethane),

VCM, liquefied Ammonia (NH3) and LNG.

AutroCAL®

AutroCAL® is a unique calibration and verification function in

the KONGSBERG system. Gas vapour density and mixture of

gases influence the propagation speed of the radar signal, thus

the accuracy of the measurement. By using pipe joint reference

markers, AutroCAL® continuously compensates for the changes

caused by the differences in the propagation speed. AutroCAL®

ensures high accuracy over the whole measurement range,

independent of the gas mixture, pressure and temperature.

With AutroCAL®, the influence of the gas vapour density and

composition is measured and compensated for automatically.

Installation

The Transmitter Barrier is typically installed in the processing

cabinet in control room. The DZ-110/U is equipped with blue

coloured terminals 4 and 5/6 for connection of the intrinsically

safe circuit in hazardous area. Terminals 2 and 3 connects the

Transmitter Barrier to an analogue input channel in the moni

toring system. The Transmitter Barrier shall be grounded to the

Intrinsically Safe busbar in the system (6), by minimum a 1.5

mm2 cable.

The DZ-110/U snaps to a TS-32 or a TS-35 mounting rail (ac

cording to DIN46277). End stoppers shall be used to support

the units.

Safety instruction:

For safety instruction see the document 373874 K-Gauge Ex I

Safety instructions.

FEATURES

• Intrinsically safe connection of 4 – 20 mA transmitters to safe

area

• Snap-on installation to DIN rail (TS-32 or TS-35)

• Small size

• ATEX, IECEx and type approved

The KONGSBERG DZ-110/U Transmitter Barrier Unit is designed to

safely provide signal interface and pow er supply to Kongsberg

instrumentation located in hazardous area. The unit connects

intrinsically safe 4-20 mA transmitters.

Principle of operation

The Transmitter Barrier is installed in safe area, designed to

limit the amount of energy that could appear in an electric circuit

that connects to instrumentation located in hazardous area.

The DZ-110/U is a single channel shunt diode safety barrier,

intended for energising a 2-wire, 4-20 mA signal transmitter

installed in hazardous area. A “current mirror” amplifier re

peats the transmitter current into an equal magnitude safe

side current. To prevent leakage through the zener diodes, the

voltage applied to the barrier section is regulated and limited

to a suitable level. Active current limiting is also incorporated to

prevent fuse blow-out during accidental shorting of the transmit

ter circuit.

Signal Processing Unit (SPU)

Each RTG is connected to a dedicated signal processing unit,

where the specific tank design data is stored.

The GLK-300 Signal Processing Unit (SPU) is located in safe

area and provides necessary communication and power barri

ers to the instrumentation located in hazardous area. The SPU

employs powerful processing of the data from the Radar Tank

Gauge and temperature transmitter.

AutroCAL®

Gas vapour density and mixture of gases influence the prop

agation speed of the radar signal, thus the accuracy of the

measurement. AutroCAL® utilizes multiple reference markers to

measure the speed of the signal down the tank and continuous

ly compensates level readings for a varying propagation speed.

Each pipe section is delivered with reference markers in the

flange joints. The liquid level and the markers are measured

simultaneously, and the system automatically verifies itself at

every measurement.

Temperature transmitter

The K-Gauge GAS system offers two alternative temperature

monitoring configurations:

Alt. 1: Up to three temperature sensors

KONGSBERG Cargo Temperature Unit (CTU), GC-300. is a

marine approved intrinsically safe signal converter and connec

tion box designed for installation on tank top for connection of

up to three temperature sensors through one tank penetration.

Alt. 2: Up to six temperature sensors

KONGSBERG Cargo Temperature Unit (CTU), GC-306. is a

marine approved intrinsically safe signal converter for con

nection of up to six temperature sensors. The transmitter is

designed to be installed in a local cabinet. A connection box for

connection of the temperature sensors on tank top is included

and provide gas sealing toward the tank atmosphere.

BUILDING BLOCKS

Radar Tank Gauge (RTG)

The KONGSBERG Radar Tank Gauge (RTG), GLA-310/5

FUEL, is designed to measure level in tanks containing lique

fied gases. Accurate measurement is possible regardless of the

tank atmospheric conditions. Flexible hardware and software

modules ensure easy adaptation to all tank designs.

The RTG consists of a microwave antenna and an electronic

unit. The electronic unit includes a sophisticated signal detec

tion method that ensures optimum performance, which com

bined with its superb signal-to-noise ratio offers the highest

measurement reliability and accuracy.

The horn antenna is designed to guide a frequency sweeping

microwave signal through a 50 mm standpipe. The distance is

derived from the time delay of the reflected signal.

The standpipe has ventilation holes allowing the vapour pres

sure inside and outside the pipe to stabilize, thus allowing the

liquid to rise or fall in the pipe. The standpipe is considered an

integrated part of the level gauge, and is delivered to match the

total tank height.

The RTG is specially designed to withstand the severe mechan

ical and physical conditions in a maritime environment. Only

AISI 316L acid-resistant steel and PTFE/PEEK materials are

used.

Functional description

K-Gauge GAS fuel tank monitoring system measure the level

by use of KONGSBERG well proven Radar Tank Gauge.

Extensive surface movements, combined with the low dielec

tric properties of LNG and LPGs, require quality instrumenta

tion and signal processing to provide reliable measurements.

KONGSBERG unique Radar Tank Gauge design, with its high

signal-to-noise ratio and powerful signal processing, offers

accurate measurement regardless of the tank atmospheric con

ditions.

The system also implement quality temperature- and pressure

transmitters, safety barriers, processing units and display panel

for local monitoring through dedicated mimics.

Flexible hardware and software modules ensure easy adapta

tion to all IMO type tank designs, and all kind of liquefied gases.

All field equipment is designed and certified for marine use,

manufactured in AISI 316L stainless steel and type approved by

the major classification societies. The intrinsically safe appara

tus is certified Ex ia according to ATEX and IECEx.

The K-Gauge GAS LNG/LPG/NH3

fuel tank monitoring system is designed to meet the classification

rules and guidelines concerning instrumentation and monitoring

of storage tanks for ships using liquified gases as fuel.

The accuracy, reliability, integrity and safety of shipboard

containment and operations are key ele ments embedded into

the system design.

System description

The implementation of dual fuel engines and growing interest

in using liquefied gases as a marine fuel, raise many practical

challenges regarding bunkering, storing and processing.

The K-Gauge GAS fuel tank monitoring system is designed to

fulfil the requirements set in the IGF Code and the challenging

demands concerning safe monitoring and storage of liquefied

gas on board ships.

KONGSBERG extensive knowhow from 20 years in produc

tion, design and servicing LNG automation and tank monitoring

systems, is embedded into complete solutions for main engine

control, Fuel Gas Supply and tank instrumentation for monitor

ing of fuel tanks for liquefied gases (LNG / LPG / NH3).

General description

The patented GL-10 sensor is designed to meet

the requirements in SOLAS Ch. XII, Reg. 12 and

Ch. II-1. Reg. 25 and intended for water level

detection in Cargo Holds, Ballast Tanks, and Dry

Spaces of Bulk Carriers.

Output signal is 2-wire 4 to 20 mA, it will give a

steady 12mA when no liquid is detected and

jump to 18mA when liquid is detected.

The sensor is delivered connected and moulded

to a flexible PUR-cable and installed into a Ø60

mm steel-tube with a length of 0.2 m.

The sensor can be mounted inside cargo hold

with a clamp or from void space with the

protecting pipe welded to the bulkhead.

The sensor can also be used as a general purpose

water ingress detector, i.e. bilge system.

The sensor is intrinsically safe EEx ia, and must

be connected to a Zener-barrier like the

Kongsberg DZ-110. when used in hazardous

areas.

Standard features

• Unique and patented liquid detection sensor

GL-10. designed for the harsh environment

in ships cargo holds.

• The sensor design contains no moving parts

and is very resistant to clogging from cargo.

• The sensor has IP68 protection and is well

suited for areas which can be filled with

water, e.g. Fore peak Tank.