What is DNV?
The
ship classification system offered by DNV (Det
Norske Veritas) is designed to safeguard life
and property in maritime environments. Obtaining
DNV Type Approval entails verification of a set
of requirements during the design, construction,
and operation of devices used on ships and offshore
units. As one of the world's leading classification
societies, DNV certification is recognized globally
as an indication that a product is fit for use
in different well-defined classes of marine environment.
Detailed information about the maritime services
offered by DNV can be found on the DNV website
at www.dnv.com/maritime.
DNV classifies
tests into four levels-A, B, C, and D-ranging
from the most basic to the most critical. The
table below indicates what level of test a device
must pass to be rated for use in a particular
location. Separate tests are conducted for different
types of condition (temperature, humidity, etc.).
For example, if you need to use a device in pump
rooms, holds, or rooms with no heating, then the
device must have passed the D-level test for temperature,
B-level test for humidity, B-level test for vibration,
and A-level test for electromagnetic compatibility.
Location classes-Selection guide
Column I |
Column II |
Parameters |
Location within main area
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MAIN AREAS ONBOARD |
Machinery spaces |
Control room,
Accommodation |
Bridge |
Pump room, Holds, Rooms with no heating |
Open Deck |
Temperature |
Inside cubicles, desks, etc. with temperature rise of 5 ° C or more |
B |
B |
B |
D |
D |
All other locations |
A |
A |
A |
C |
D |
Humidity |
Locations where special precautions are taken to avoid condensation |
A |
A |
A |
A |
A |
All other locations |
B |
B |
B |
B |
B |
Vibration |
On machinery such as internal combustion engines, compressors, pumps, including piping on such machinery |
B |
- |
- |
B |
B |
Masts |
- |
- |
- |
- |
C |
All other locations |
A |
A |
A |
A |
A |
EMC Electro-
magnetic compatibility |
All other locations within specified main areas |
A |
A |
B |
A |
B |
Enclosure |
Submerged application |
D |
- |
- |
D |
D |
Below floor plates in engine room |
C |
- |
- |
- |
- |
All other locations |
B |
A |
A |
B |
C |
* |
The different Locations have different Minimum test level requirements; class A is the basic test level, and class D is the most critical test level for each different Location. |
Moxa's EDS Industrial
Ethernet Switch family and IMC Industrial Media
Converter family have received DNV Certification,
and all tests meet or exceed the requirements
of the guidelines laid out in ICAS Unified Requirement
E10 and the relevant sections of IEC945 for equipment
housed within a protected environment. In particular,
the products have passed the D-level test for
Temperature, B-level test for Humidity, A-level
test for Vibration, and B-level test for EMC.
The Det Norske Veritas Type Approval Certificate
for Moxa's products can be viewed on the DNV website
as Certificate
No. A-9488.
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DNV in the Maritime Oil & Gas Industry
Offshore drilling for oil
and gas began more than 100 years
ago in the 1880's with wells dug from
wharfs extending several hundred meters
out into the ocean from the coast
of California. However, it wasn't
until after the end of World War II
in the 1940's that drilling moved
completely offshore, with wells sunk
from platforms floating out of sight
of land. DNV's own rise to being a
leader in supplying risk management
services to the international oil
and gas industry began in the 1960's
when Norway got started with oil and
gas exploration.
The services that DNV
provides to the oil and gas industry
are varied. To get an idea of just
how extensive DNV's involvement is,
note that DNV classifies 30 percent
of the offshore oil and gas tonnage
for the entire world. DNV also provides
expert assistance with offshore construction,
from the planning and design stages,
all the way through building, operation,
and even decommissioning.
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Maritime
as the Next Step in the Ethernet Trend
The industrial
Ethernet movement evolved from the
realization that Ethernet products
designed for a comfortable, well-controlled
office setting were not suitable for
use in harsh, less predictable industrial
environments. The main reason is that
commercial Ethernet equipment cannot
meet the high reliability requirements
demanded by industrial applications.
In addition, industrial environments
can be extremely hot, or unbearably
cold, so that specially designed,
more robust network equipment is required.
The industrial
Ethernet revolution was also fueled
by the fact that an increasing number
of device manufacturers, such as PLC,
DCS system, and field I/O manufacturers,
now produce products that come with
a built-in Ethernet interface. And
since Ethernet is based on an open
standard, users are not bound by product
manufacturers' proprietary protocols
and network structure. This simplifies
the user's task substantially, since
many different types of device can
communicate with each other by just
plugging the devices into the same
network.
This
trend of using Ethernet for industrial
applications has taken a new twist
with the realization that Ethernet
can be used to solve communications
problems for a number of marine applications.
In fact, many industrial Ethernet
devices, such as Moxa's own switches
and media converters, designed originally
for applications on land, have been
found equally well suited for use
in adverse marine-type environments.
Examples include battleships and ocean
liners, which when fully manned could
be home to several thousand soldiers
or passengers. Energy related applications,
such as offshore drilling platforms,
tide-power generation systems, and
offshore windmill farms, could also
benefit from using Ethernet.
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Using
Ethernet with Maritime Applications
As mentioned
in the previous section, some Ethernet
devices, such as switches and media
converters, are now rugged enough
to be used with maritime applications.
In this section, we examine five such
applications in more detail.
Battleships
- Although the overall purpose of
the battleship has not changed, the
modern battleship differs considerably
from its predecessors, particularly
with the numbers and types of automatic
control systems that are used. For
example, automatic combat systems
used on battleships coordinate data
from radar, sonar, weapons, and communications,
all of which are controlled by separate,
highly sophisticated computer systems.
The combat system uses Ethernet networks
with fiber optics, with each subsystem
collecting data for C4ISR (Command,
Control, Communications, Computer,
Intelligence, Surveillance, and Reconnaissance¡Xe.g.,
see the website www.c4isrjournal.com)
operations. Using Ethernet makes it
much easier for designers of battleship
systems to use one control center
to coordinate data from many different
systems, making it possible to analyze
all information, and provide the battleship's
commander with suitable integrated
information for formulating attack
and defence decisions.
Ocean
Liners - When filled to capacity,
a large ocean liner is essentially
a floating city, with all the same
infrastructure and public service
requirements. In addition to having
access to a variety of restaurants
and recreational activities, passengers
now also demand access to e-mail accounts
and the Internet, real-time news,
and even information exchange services
such as MSN. By providing such services,
as well as network games and VOD (Video
On Demand), ocean liners can satisfy
the requirements of traveling businessmen
on vacation with their families. Ethernet
networks on ships must be capable
of operating in critical environmental
conditions that include severe vibrations,
high humidity, and hot temperatures.
In addition, the networks must be
immune from interference caused by
other devices used on the ship. As
far as switches are concerned, the
only option for reliable on-ship operation
is a rugged industrial Ethernet switch
designed to work in these kinds of
adverse environments.
Offshore
Platforms - Offshore platforms
are used to drill for oil and gas,
setting up meteorological stations,
and hydrology. Devices used on offshore
platforms must be capable of withstanding
any number of critical ocean environments,
including the effects of moisture,
vibration, shock, and temperature
extremes. To ensure that all systems
work properly, it is necessary to
set up a sophisticated automated monitoring
system. Using an IP network for the
monitoring system makes it easier
to set up a coordinated, platform-wide
system that connects control and video
systems into one network.
Tide-power
Generators - Although most of
us have witnessed the motion of the
tides when visiting coastal areas,
we probably didn't consider the amount
of power involved in moving such massive
volumes of water up and down twice
per day. Electric generating systems
that use tidal power are one answer
to the problem of finding a "clean"
replacement for fossil fuels. However,
since this type of system is by necessity
spread out along the coast, a modern
communication system is required to
coordinate, monitor, and control the
various components and devices making
up the system. By using an Ethernet
network, video and control systems
can be integrated as part of the same
system-wide network, allowing operators
to monitor the status of the entire
system. The video system is used to
view and record a variety of images,
and helps to analyze the efficiency
of the system and adjust the settings
of equipment.
Offshore
Wind Power -Traditionally, windmills
are used onland in areas that experience
steady, relatively high speed winds.
A prime example is the Netherlands,
for which windmills have been an important
part of the power system for many
decades. Another option is to place
windmills offshore in coastal areas
that are prone to steady winds. Offshore
windmill farms, which could consist
of many large windmills located along
a coastal area, can benefit greatly
from using fiber optics as a communication
medium. Fiber optics is not only capable
of transmitting signals several kilometers,
but fiber optic equipment tends to
have a high MTBF, making the equipment
more stable and reliable.
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Summary
The convenience
of using Ethernet has been a major
impetus for adapting Ethernet to many
different disciplines and a wide range
of environments. Another aspect of
Ethernet that makes it so popular
is that system integrators can easily
combine signals from different types
of devices and protocols to create
a system-wide monitoring and control
system. With the availability of rugged
industrial Ethernet devices rated
for use in maritime environments,
such as the EDS switches and IMC media
converters from Moxa, Ethernet is
sure to be used more and more for
marine applications, such as on ships
and offshore platforms.
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