K Controls sub-sea
valve position monitors have been specified for use Aquamarine Power’s Oyster
wave energy device that captures energy in near shore waves and converts it
into clean sustainable electricity. The valves will control the flow of the
high pressure water that is generated by the movement of the wave flap and
associated hydraulic pistons and then moved onshore, via a pipeline, to drive a
conventional hydro-electric turbine. Low pressure pipes will transport the
water back from the hydroelectric power station to the wave energy device.
It meets all of
the clients requirements and can be calibrated remotely using the HART®
protocol without diver intervention.
The field proven
sub-sea position monitor has been used on applications that include:
the position of hydraulically actuated valves that flood the jackets on
the legs of oil rigs during satellite guided positioning.
the position of failsafe valves on conventional tanker buoy mooring
the position of valves in the ballast tanks of semi-submersible oil rigs.
devices are important because the central aim of UK Government energy policy is
to establish a supply of energy that is diverse, sustainable, secure and
competitively priced. Ocean waves represent our planet's last untapped natural
renewable energy resource. The energy contained within waves has the
potential to produce up to 80,000TWh of electricity per year - sufficient to
meet global energy demand five times over. Wave energy is, by its nature, a
clean energy resource. Aside from the energy expended in manufacture and
installation of wave energy devices, it produces no carbon emissions. In
the future, subsea pipelines will connect multiple wave energy devices to a
single onshore plant creating wave farms of several hundred connected devices
generating hundreds of megawatts of electricity. The devices sit largely
underwater so there is minimal visual impact.
There is also a
link between wave energy and desalination - the process of removing salt from
water to produce freshwater. Energy fuelled by diesel generators is
currently used to pump high pressure saltwater over special membranes to
produce freshwater. A wave energy device offers a cleaner, more cost-effective
solution. It could be configured to produce high pressure saltwater direct to a
desalination plant, without the need for any fossil fuels.
The 007-100 and 007-120 Exd or Exia
IIC Valve Position Monitors are now ATEX, IECEx or INMETRO certified for use in gas Zones 1 and 2
and dust Zones 21 and 22. Exd and AExd versions are also available with NEC 505 cCSAus certification marking for use
in Canada and the USA.
For Canada the products are gas certified Ex d IIC T6 and dust
certified Ex tb IIIC, Class II, Groups E, F and G; IP66/IP67 or IP68. For the USA the
products are gas certified Class I Zone 1, AEx d IIC T6 and dust certified Zone
21, AEx tb/tD T85oC; IP66/IP67 or IP68.
Does the "T" class of hazardous area equipment (e.g. T4, T5, T6) define the maximum temperature of the surrounding environment in which the equipment can be installed? For example in the case of T4 is the maximum ambient temperature 135ºC?
We have been asked this question a number of times recently and the answer is "No".
The "T" class is interpreted in one of two ways:
The maximum surface temperature of the apparatus - In the case of T4 the maximum surface temperature of the apparatus must not exceed 135ºC degrees C.
The auto ignition temperature of a particular gas - The auto ignition temperatures of all the gasses in group T4 will be greater than 135ºC and less than 200ºC.
The contents of the apparatus will increase the surface temperature of the apparatus when power is applied; during both normal operation and under fault conditions.
As an allowance needs to be made for this temperature rise, the maximum ambient temperature (T amb) of the apparatus can operate in also needs to be defined.
This maximum ambient temperature e.g.+ 40ºC or + 80ºC, will therefore be lower than the temperature defined by the relevant T class, e.g. 135ºC (T4).
A given piece of electrical equipment will therefore be approved for a stated range of ambient temperatures in which it is safe to operate.
Normally this would be T amb -20ºC to +40ºC, unless otherwise stated on the product certification.
K Controls can offer certain products with a T amb as low as -60ºC or as high as +120ºC.
In summary you will need to know the T class and the T amb (maximum and minimum) in order to specify the correct equipment.
(For further information on the T class please click here).