62 INSTRUMENTATION/COMPUTING/CONTROL
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is becoming well accepted as the standard of good practice for safety instruments systems in the process sector. It’s certainly not a legal requirement in itself, but the requirement to implement good practice is a legal requirement.” The 2007 Frost and Sullivan report “World Safety Systems Markets for Process Industries” stated that the safety systems market represented US$1 billion in 2006 and was expected to double by the year 2013. However, despite the boom in safety programmable systems and growing awareness within industry, the IEC 61511 standard is still misinterpreted whilst knowledge and competence gradually diffuses throughout international networks and supply chains. IEC 61511 is currently under maintenance and the committee is working towards international acceptance on a number of important points that will be addressed in the revised standard. Key topics explored in the roundtable discussion include the effect of the revised IEC 61508 standard on its 61511 derivative, the clarification of “prior in use”, as well as specific parts such as hardware fault tolerance (HFT), the safety manual, clause 12, SIL 4 and PFD calculations. A new revision of the IEC 61508 ‘umbrella standard’ is imminent which will have an immediate effect on the current IEC 61511 and its future revision. The subject of ‘prior in use’ has been the root of enthusiastic debate within industry, and some parties argue that it is open to interpretation. This has important implications for end users, consultants and for manufacturers. Aart Pruysen of Emerson Process Management commented: “There are many process conditions that are included in the prior use claim that can only be observed by the end user.
It’s also a matter of
liability in case something happens, and who would be responsible. I think the standard, at this moment, makes it very clear that only end users can do that.” IEC61511 bridged many different areas of technology on a process plant (hazard and risk analysis, reliability engineering, quantitative analysis, instrumentation and testing). Committee chairman Maggioli explained: “The result was a new series of technological issues such as layer of protection analysis, safe failure fraction, and probability of failure on demand that has required further definition as the standard is revised.”
The continuing evolution of technology, including
wireless, safety fieldbus, safety software and SIL certified devices, has also impacted the standard. In the video, Maggioli comments on the current status of the IEC61511 revisions, “I expect that you will see changes in the clause 12 software and hardware fault tolerance section. You may not see as many changes in SIL 4, the safety manual and PFD calculations.”
T
the Verderflex Dura range of peristaltic hose pumps.
V
The Dura 35 delivers a maximum continuous flow rate of 3180 l/hr or 840 GPH at pressures up to 16Bar or 230PSI. Weighing just 125kg and taking up to 70 per cent less floor space than similar pumps, the Dura 35 will free up vital working areas to replace more outdated technology.
Dura has fewer system components than other peristaltic pumps, reducing downtime with a novel drive configuration that requires much less space.
Running at a significantly lower
erderflex has launched the Dura 35, the latest addition to
o find out more about the topics discussed, the maintenance of the IEC 61511 standard and its application first hand visit
www.safetyusersgroup.com and follow
the IEC 61511 interview banner. The SUG’s online knowledge base comprises more than 6000 pages of technical papers, white papers, video interviews, reports and training resources about intrinsically safe and explosion proof technology (ATEX), standards and regulations (such as IEC 61508 and 61511), risk management, safety lifecycle, process safety management and maintenance strategies. For more see
http://www.safetyusersgroup.com o
PERISTALTIC PUMP DELIVERS FLOW RATE OF 3180 L/HR
operating temperature than equivalent pumps, hose life is improved by up to 40 per cent.
Designed so that the drive is mounted on a torque arm and totally isolated from the housing. There is an air gap between pump casing and gearbox which protects both the pump lubricant, inside casing and the drive’s gearbox. They can ‘never’ cross contaminate and there is no need to remove the drive when servicing the pump.
A one piece taper lock flange connection speeds up hose changes and the universal slotted connection offers a one size fits all solution, meeting the requirements of ANSI, JIS and PN16, improving part availability.
www.engineerlive.com
Dura also offers health and safety benefits in the form of quieter action and drive configuration.
The Dura series consists of smaller hose pumps; the Dura10, Dura15 and Dura25, based on a long coupled design with close coupled advantages. The bearing construction is ‘sealed for life’ and centrally absorbs the forces released in the pump. This results in quieter operation and a more durable pump and drive.
The drive shaft has been designed to reduce the loading on the gearbox and motor.
Enter 62 or ✔ at
www.engineerlive.com/iog
Verder Ltd is based in Hunslet, Leeds, UK.
www.passionforpumps.com
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