Safe and Sound in Hazardous Areas.

 Intrinsically Safe (IS) approved field calibrators
 reduce breakdown and maintenance costs,
 improve process efficiency and safety.
In many process industry sectors, the safe and efficient handling and production of potentially hazardous liquids and gases is an everyday challenge. Examples range from sewage treatment to petrochemical fuel distillation, wet gas separation to hydrogen cooled power generators amongst many others. Working in such hazardous areas requires extreme care and the law places great responsibility upon individuals, because the potential for disaster is high. Effective process maintenance schedules are essential and need to be carefully planned, implemented and documented to keep plant systems running efficiently, whilst safely achieving maximum levels of productivity. Production costs are extremely high so inevitably a fast response to any system fault, breakdown or failure is also vital to keep losses to an absolute minimum. Just a few minutes of plant downtime can cost tens of thousands of pounds. Above all, safety is of paramount importance. To improve working safety, legislation classifies hazardous areas into zones 0, 1 or 2, according to the continuous, intermittent or abnormal presence of explosive gases or air mixtures. These gases or air mixtures are also classified by gas group and temperature. Dependant upon factors such as gas sensitivity and surface temperatures, just a few millijoules of electrical spark energy can cause ignition. The use of electrical equipment such as field calibrators is therefore restricted within the zoned areas unless it has been approved as "IntrinsicallySafe" (IS). Non-IS equipment reduces the ability for plant technicians and other personnel to quickly implement maintenance schedules, or even worse, their ability to respond quickly to failures or breakdown. Typically, they must first report to the plant manager, obtain authorisation documents, locate suitable gas detectors and then sign a permit to work. The user is then accepting a burden of responsibility for continually monitoring the hazardous environment whilst carrying out maintenance or troubleshooting duties within the often remote or difficult site conditions. This burden is made worse in the knowledge that considerable process losses are incurred purely due to the delay in even entering the affected area.
Intrinsically Safe Calibrators Dependent on the choice of field calibrator for a particular task, delays and errors in implementing and documenting test activities may be avoided or introduced. Often a calibrator is required to directly measure and/or simulate parameters such as pressure, temperature, electrical and frequency in order to find a fault with instruments or associated control loops under emergency shutdown conditions. Examples include sensors, switches, gauges, transmitters, thermocouples and RID's, etc. Calibrators are also used for minimal routine preventative checks and monitoring instrument or system performance. As part of a quality assured and often computerised operational management system, e.g. ISO 9000, they also perform periodic yet comprehensive in-situ calibration of field instrumentation in accordance with very specific test procedures and work schedules. Despite the evolution of non-IS field calibrators, relatively few IS approved products exist. However, intelligent and fully self-contained IS field calibrators are available. They are accurate, simple to use and a choice of specifications can be supplied according to specific user requirements. Developments in functionality and communications reduce the demands on operator skill/training and so increase productivity and peace of mind. Intrinsically safe versions are supplied fully certified and approved for immediate and direct use in hazardous areas, avoiding the need for bulky gas detectors and associated safety documentation, which in turn reduces delays in operator response and minimises downtime. The precise choice of IS calibrator will ensure that the most cost effective and convenient solution is applied for addressing a task or range of tasks within specific user applications. This may be a Smart 4 - 20 mA loop tester, a combined pressure/electrical calibrator and troubleshooter or even a powerful multi-function documenting process calibrator with PC based management software. Specialist manufacturers include Druck who have supplied IS calibrators for almost 20 years and offer a complete product range, enabling the critically important choice of equipment to be made without compromise. The user benefits from a "customised" approach which may include just one calibrator or several different types. Performance capabilities will be very closely matched to ensure optimum results for the tasks involved.
Product Developments Today's leading field calibrators embrace a wealth of developments in measuring, interfacing and packaging technologies which directly benefit the user in terms of overall test efficiency, speed and quality. For example, high accuracy measurements can be readily made with precision low-doped and resonant silicon pressure elements, auto-detection of 2, 3 or 4 wire RTD's, internal point-of-contact thermocouple cold junction compensation. This advanced measurement technology is then complemented by task oriented dual parameter graphic displays which can be configured for simplified routine calibration and maintenance or advanced troubleshooting at the touch of a button. The result is fast set-up and implementation for both process maintenance and calibration tasks. Multi-function hand pumps can now precisely and very rapidly source up to 60 bar pneumatic or 700 bar hydraulic test pressures and 95% vacuum. Compact, rugged and ergonomically designed packaging eases practical use of the calibrator and prolongs its useful life in harsh field environments. Complete test routines can be pre-loaded into the calibrator and recalled for automated field implementation. At the end of a workshift the results can be simply uploaded direct into a PC. Using electronic data storage, by means of either RS 232 communications protocol or PCMCIA card, reduces the possibility for errors because the recording of data and its transfer to a centralised test and calibration management system is both automated and paperless. To further enhance this "low risk" documentation process and to simplify the necessary compliance with quality standards such as ISO 9000, approved calibration software can also be supplied. For users who do not have their own established system, proprietary software packages are available, often provided by the calibrator manufacturers themselves, which satisfy the full range of test, calibration and documentation management requirements. This includes, for example, the creation of multiple databases to organise data storage, a powerful search engine for simplified data retrieval and a multi-level security password system to prevent unauthorised system entry. Moreover, test procedures and individual specific work orders can be generated for down loading to the portable calibrator. At the end of the daily work shift, resulting data collected in the field is simply uploaded back at the office PC for creating records and further analysis/processing. Detailed and quality compliant calibration certificates can then be automatically generated, making the whoIe process far easier and more reliable than the traditional manual paperwork approach. These and many other continual developments recognise the importance of the field calibrator's role in improving hazardous process safety, efficiency, quality and reliability. _______________________________________________________ November 2000

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