TECHNOLOGY IN ACTION ADVERTORIAL


Compressed Air Guidelines


Compliance with BCAS Food & Beverage


T


he British Compressed Air Society has new Best Practice Guidelines, in conjunction with the BRC


and the Food and Beverage industry requirements. Safety in processing and production is vital, but Thorite ensures compliance. The guidelines cover the compressed air equipment required, installation, maintenance and air purity requirements,


plus


provisions for compressed air in food and beverage manufacturing specified in the BRC Global Standard for Food Safety ISO 22000/ISO TS 22002-1. Production processes are affected in 2 ways: Direct Contact, where compressed air contacts during production, processing, packaging or transportation and Indirect Contact where compressed air is in the atmosphere during food preparation,


production,


processing, packaging or storage. Thorite’s expert engineers identify critical applications of the Air Quality Audit-HACCP Process and provide solutions to guarantee air purity.


Thorite u ross.gowler@thorite.co.uk u www.thorite.co.uk


enter 819


Spirax Sarco products and expertise help to end production woes for Sarval


pirax Sarco has designed and supplied a new steam system for animal feed producer Sarval (Hartshill) Ltd to overcome production problems caused by wet steam. Spirax Sarco project managed the system’s design and installation and also supplied the pipework, valves, steam traps and flow meters for the new £18 million facility. Previously, the Hartshill site had suffered numerous brief interruptions to production, a problem suspected of being linked to wet steam, which caused boiler water levels to fluctuate and the boilers to shut down. Mr. Terry Smith, Group Energy & Technical Support Saria UK, comments: “The problem was down to the way the plant had grown over time. Sections had been added ad hoc, there were a lot of bends in the pipework, and some of the pipes were too narrow. It is hard to quantify how much these problems cost, but it could have been


S


thousands of pounds a month. However, the new system will put an end to that, because it has been designed around the needs of the process.” Spirax Sarco also supplied energy-saving equipment such as steam traps and flow meters to help the company achieve its energy-saving goals. Sarval also retained the Spirax Sarco FREME (Flash Recovery Energy Management Equipment) it installed in 2005 to help it recover flash steam and which, says Mr Smith, has cut its annual gas bill by around £100,000. The new pipework has helped eliminate the problem of wet steam and ensure efficient steam delivery to the


new production equipment, contributing to significant energy savings.


Spirax Sarco u 01242 521 361 u www.spiraxsarco.com/uk


enter 820 Do PLe applications need two interlocks? T


here is a lot of interest in whether redundancy is required when it comes to interlock actuators. This debate has been going on for many years but really gained momentum in 2012 by the inclusion of a note in table D8 in 13849-2- 2012: ‘For PLe a fault exclusion for mechanical (e. g. the mechanical link between actuator and contact element) and electrical aspects is not allowed. In this case redundancy is necessary’


Now that EN ISO 14119 (The Interlock standard) has been published, it adds to the debate with the following two paragraphs in section 8 with relation to ‘Assessments of faults’ and ‘Fault Exclusions’: ‘Where an interlock system requires PLr e……... In order to achieve this it is normally not justifiable to exclude faults, such as broken actuators.’ ‘There should be a proper selection of the device ensuring that the holding force (Fzh – see 5.7.4) of the guard locking device is sufficient…….. In this case the use of fault exclusion for breakage of the locking element does not necessarily limit the PL or SIL for the guard locking function.’


So what exactly does this all mean?


Clearly there is variability in what the standards say about fault exclusions, with statements ranging from ‘not allowed’ through ‘normally not justifiable’ to ‘not necessarily limit’. However the common thread is: The possibility of actuators breaking must be considered very carefully for PLe applications. With a typical interlock this is fully understandable, as it is not uncommon for actuators to break, leaving the interlock in a fail-to-danger condition.


When designing the Fortress amGard Pro heads and actuators, the objective


was to create an indestructible product to meet the interlock standard. With all loadbearing components manufactured from over-dimensioned cast stainless steel, the amGard Pro actuator absorbs more than 50 times the energy of a typical actuator, and the head remains attached beyond loads of 4,000 kg. The end result is a unit with strength beyond that of the hinges, fittings and even the guarding itself.


It is this over-dimensioning, rigorous testing and data from 3 billion hours of in-service use which allows Fortress to recommend the amGard Pro as a PLe interlock without requiring a secondary interlock.


Conclusion


For PLe applications careful consideration must be given to the actuator. If a normal pressed actuator is to be used then, in all but the lightest duty appli- cations, a secondary interlock should be used.


Alternatively an interlock which incorporates an actuator and a separate non-contact sensor could be used. The Fortress amGard Pro interlock, on the other hand, having an actuator that is stronger than the rest of the guarding, provides the simplest solution to achieving a PLe rating.


Fortress Interlocks Ltd u 01902 349000 u www.fortressinterlocks.com


/FACTORY EQUIPMENT


enter 821 DECEMBER 2014/JANUARY 2015 | FACTORY EQUIPMENT 31


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