New Vented Oxygen Sensor Moves Reliability, Stability and Performance to a New Level
Rob White, City Technology City Technology Centre, Walton Road, Portsmouth, PO6 1SZ, UK Tel: + 44 2392 3255111 • Fax: + 44 2392 386611 • Email:
sensors@citytech.com • Web:
www.citytech.com
More than 95% of City’s oxygen sensors are installed in personal life safety equipment, giving security and peace of mind to individuals whose duties involve entering the potentially hazardous
environments to be found in numerous diverse different industries. When working in the oil and gas industry, wastewater treatment, the marine sector, civil engineering, chemical manufacturing or any other industry where reduced oxygen content is a potential hazard, people must be provided with reliable and accurate equipment that will warn them instantly if the oxygen level is reduced. Obviously, the performance of the detection instrument depends on the performance of the sensing element, so the stability and reliability of the gas sensor is of fundamental importance.
Can utopia be achieved?
“I have seen the future, and it works.”, so said Lincoln Steffens in 1921. Originally said in a very different context, Steffen’s words could now be applied, with total veracity, to the more esoteric world of the electrochemical oxygen sensors that are at the heart of today’s portable gas detection instruments. City Technology designs, develops and manufactures gas sensors for personal life safety equipment. City makes a considerable investment in research and development every year in order to bring to market new products that offer instrument manufacturers and end users enhanced performance and benefits to improve the functionality, reliability and effectiveness of PPE. The introduction of 4OXV, the new oxygen sensor, is a major advance for the life safety industry. Bringing the benefits of advanced technology, automated manufacturing, extensive testing and impeccable quality, 4OXV consigns to history the issues that currently cost both OEMs and end users a considerable amount of time and effort.
City research shows that the key issues concerning manufacturers and users are:
Warranty returns Industry-wide, anecdotal evidence suggests that up to 15% of oxygen sensors are returned for replacement under warranty. City’s actual rate for safety oxygen sensors is slightly less than 5%, significantly better than the industry average, but, nevertheless, in itself an unacceptably high figure.
Cost Reliability
Plagued by false alarms and premature failures, end users regard gas detection instruments with an understandably jaundiced eye.
Certainty
The majority of oxygen sensors are sold with the promise of a two-year operating life. Regrettably, a significant proportion will fail to function before the end of the expected lifetime.
Capability
Required to operate in some of the most inhospitable environments to be found on the planet, all too often the oxygen sensor cannot cope with extremes of temperature, humidity and pressure, failing to perform both in steady state and rapidly changing conditions.
The various shortcomings enumerated above have a significant cumulative cost to end users. There are the on-site costs of responding to failed or false readings from instruments; in safety-critical environments, alarms cannot be lightly dismissed, so replacement units have to purchased and held in stock to cater for on-site outages. The ultimate scenario is a partial or full plant shut-down as the result of a false reading from a gas detection instrument. Technological utopia would be a state where instruments never fail prematurely in use; where warranty claims are, to all intents and purposes, non-existent and where routine sensor replacement at the end of the two-year life cycle is the norm, but in the real world this is unachievable. However, although the cost consequences to the end user, being infinitely variable, cannot be realistically quantified, improved performance by the oxygen sensor will significantly reduce the costs of premature failure.
To paraphrase: “I have seen the future: it works and it’s called 4OXV.”
4OXV
Extensive analysis of the main causes of oxygen sensor premature failure shows that they fall into three main areas: • lead exhaustion • electrolyte leakage • inappropriate response to environmental variability - false alarms
4OXV has been developed to overcome these issues: exhaustive testing has proved the point. It is the culmination of a five year, multi-million dollar, multi-disciplinary development programme. A 20+ strong team of scientists and engineers have been involved in the design and development, and more than 9500 hours of extended testing has proven that their
IET November / December 2011
www.envirotech-online.com
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