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Feature Hazardous areas & safety
Taking cabinets into hazardous areas
When working with volatile liquids and gases, hazardous
areas are often involved. Historically, control cabinets
combining electrical and pneumatic devices could not be
used in such areas. Now, however, Burkert has developed
its AirLINE Ex 8650 system, with modules from Siemens
SIMATIC ET 200iSP, which provides an ATEX certified unit
U
ntil recently, combining electri- safe area is a further option – although
cal and pneumatic devices in often not possible as the large distances
control cabinets in zone 1/21 between valves and actuators lead to
environments was impossible unacceptably long switching times.
due to the wet and oily compressed
air, which caused corrosion and short Reducing the wiring effort
circuits. Today, however, compressed However, connecting sensors and
The combination of
pheres. It is suited to decentralised
air systems usually work with air qual- actuators to bus systems reduces the
Burkert and
process control tasks concerning fine
ities with a pressure dew point below - wiring effort. The use of advanced
Siemens’ products
chemicals, pharmaceuticals and cos-
20°C (residual moisture of 0.88 g/m
3
) Profibus DPV1 communications
has led to the devel-
metics; and it can be employed any-
and an oil concentration of less than 1 relieves the control engineer of the
opment of an ATEX
where where solvents, alcohol or
mg/m
3
. Moreover, in the pharmaceuti- task of installing the many special
certified control
lacquers are utilised. It can even be
cal and food and beverage sectors one expensive electrical junctions and ter-
cabinet
installed for direct factory automation:
can expect even better compressed air minations required by conventional e.g. for the automatic filling of sol-
quality. The quality of the exhausted field wired systems in ATEX areas. It vents, alcohol or lacquers. In these
compressed air is so good that it can be also offers additional benefits, includ- application areas, the new system is
channelled into the control cabinet in ing a more compact control system, a said to be the only compact electro-
order to prevent humidity or dust more ‘close-to-the-process’ installa- pneumatic automation solution allow-
within the ambient air from entering tion, simplified documentation and ing integration of EExia pneumatic
the cabinet. With this arrangement, a minimal power consumption, and valves without additional wiring.
pressure release facility or exhauster is hence, cost savings.
necessary. In addition, the Ex-proof electro- Combining modules
pneumatic automation system offers Standardised interfaces and modular
Detonation risk another advantage: all elements, design allow pneumatic, electric and
Whilst working with dry and oil-free air valves etc are harmonised and certi- electronic modules with diverse func-
reduces the problem of corrosion and fied. This means that users do not have tions to be combined with each other.
short circuits, there is still a detonation to provide evidence of the safety of the The system allows up to 48 Burkert
risk that remains because of the process system. Instead, Burkert provides a EExia solenoid valves to be seamlessly
conditions. In zone 1/21 hazardous certificate covering the complete con- combined with Siemens ET200iSP
areas, the pneumatic control of cylin- trol cabinet, enabling users to guaran- EExia/ib electronic digital and ana-
ders and pneumatic actuators is gener- tee that all devices and elements are logue I/O modules in single distributed
ally achieved with either discrete consistent to EN 60079 part I/O assemblies. These offer facilities for
explosion-proof valves, directly 0/1/7/11/26 and EN 60529. remote parameter setting and diagnos-
mounted to the actuator, or Ex-proof As the AirLine Ex 8650 unit is fully tics, the ability to “Hot-Swap” valves
valve banks wired to a remote-I/O- certified, it can be used in explosion- and electronic I/O modules under Ex-
system. Installing the pilot valves in a hazard areas with gas or dust atmos- conditions, and the facility for easy
system expansion later. The pilot
Controlling dust and fumes
valves integrated in the pneumatic
modules allow a range of actuators to be
D
ust and fume extraction company Flextraction has designed, built and delivered a Downdraft extraction booth and a
controlled in the field.
Downflow extraction booth to a German manufacturer of wet grinding, mixing and kneading products used in the man-
All options for combined electrical
and pneumatic system solutions
ufacture of inks, paints, plastics, chemicals, ceramics and minerals.
within explosion-hazard zones 1/21,
The 2m Downdraft extraction booth is designed to control fumes created during liquid solvents dispensing and the 2m
including maintenance and diagnostic
Downflow extraction booth is designed to control dust during the weighing of glass powders. Both booths are made from
functions, are achievable and open.
304 stainless steel and meet CoSHH legislation requirements.
The SIMATIC ET 200iSP communi-
The Downflow booth is a one piece design, and the fan enclosure is acoustically lined to reduce noise levels. The air
cates via Profibus DP Fieldbus using
is collected at low level and filtered through 3-stage primary, roughing and secondary bag filters, and finally through
IS couplers, providing openness and
HEPA filters which are said to provide 99.95% filtration efficiency. The filtered air is discharged above the operator’s head flexibility, and guaranteeing high
with an evenly distributed down flow of 0.5m/second. This system provides a continuous downflow to suppress dust availability and investment security
below the operator’s breathing zone into the extraction area. Pressure indicating devices and automatic control of the vari- due to international standardisation of
able speed fans monitor the extraction performance of the booth.
the bus protocol.
The Downdraft booth provides a laminar air flow with fumes being filtered through F7 category primary filter and car-
bon filter. Extraction is through a rear mounted centrifugal fan discharging back into the room where this booth is located.
Burkert Fluid Control Systems
Flextraction T: 01664 410641 www.flextraction.co.uk Enter 207 T: 01453 731353 Enter 208
www.burkert.co.uk
Process & Control JUNE 2009 15
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