Lead-Free Oxygen Sensors – Special Edition
In this technical bulletin, we focus on lead-free
oxygen sensors and the key considerations for instrument manufacturers when selecting lead-free oxygen sensors.
To read the full articles on these topics, please visit DDS’s dedicated lead-free oxygen sensor homepage.
What role does lead play in lead-based oxygen sensors?
Lead-based oxygen sensors operate on the so-called galvanic cell principle. Sensors of this type rely on a lead anode within the sensor body to facilitate the electrochemical reactions used to measure oxygen.
The electrochemical reactions inside a galvanic oxygen sensor consume the active material of the lead anode until it fails, rendering the sensor inoperable. Per sensor specifications, the consumable nature of the lead anode directly translates to a sensor service life of approximately 1, 2, or 3 years.
For more information, including a video demonstration of how galvanic oxygen sensors work, please visit the DDS lead-free oxygen homepage.
What options are available to OEMs without lead?
Sensor manufacturers have long been aware of the potential impacts of RoHS, and over this period, the industry has worked to deliver a viable lead-free alternative that does not depend on the galvanic principle. This effort has led to the development of amperometric lead-free oxygen sensors, a technology now used in gas detection instruments across many markets.
Although the adoption of amperometric oxygen sensors was driven by RoHS compliance, their market presence has revealed the drawbacks of leaded oxygen sensors, and they are now the preferred choice for oxygen monitoring in both newly developed products and existing product updates.
First introduced roughly a decade ago, amperometric oxygen sensors enhance instrument performance while significantly reducing maintenance burdens and associated costs for instrument users.
What is an amperometric lead-free oxygen sensor?
Amperometric sensors differ significantly from their galvanic lead-based oxygen sensor counterparts in that they require no anode to operate and therefore contain no consumable components. This is a decisive factor that enables amperometric oxygen sensors to operate with minimal output drift for more than 5 years.
Modern lead-free amperometric oxygen sensors are not only priced comparably to galvanic lead-based sensors but also offer vastly superior performance. In fact, the new amperometric lead-free oxygen sensors outperform galvanic lead-based sensors across all key performance criteria, from response time to temperature range, and most importantly, in extended sensor lifetime.
Learn more about amperometric lead-free oxygen sensors, including viewing a video demonstration of their operation, on our lead-free oxygen homepage.
What are the benefits of amperometric oxygen sensors?
Modern lead-free amperometric sensors offer numerous advantages over galvanic alternatives, including:
7× faster T90 response time plus quicker recovery for more accurate instrument readings, especially in low-oxygen applications such as inert gas environments.
Operating life extended to over 5 years – directly improving reliability, reducing downtime, and eliminating the costly and logistically burdensome annual/periodic maintenance associated with lead-based sensors.
Inherently leak-proof design – amperometric oxygen sensors function on a completely different principle than galvanic sensors, meaning they are immune to internal pressure build-up that causes leakage in galvanic units. Their leak-free nature reduces instrument downtime and costly repairs.
Wide operating temperature range – typically broader than that of galvanic-type sensors, allowing equipment to operate reliably across more diverse environmental conditions.
Improved baseline drift – delivering higher accuracy for oxygen readings, particularly at low concentrations.
Higher resolution – enabling generally faster and more precise responses to small changes in oxygen concentration.
Reduced output drift – with drift as low as 5% over the sensor lifetime, giving OEMs and users greater confidence in their instruments and allowing extended calibration intervals.
One sensor fits all – modern amperometric sensors perform equally well in both pumped and diffusion-type instruments, eliminating the need for different sensors per instrument model.
Standardization – thanks to the performance enhancements amperometric oxygen sensors bring to instruments, many device manufacturers have chosen to standardize this technology globally rather than maintain multiple SKUs.
Alignment with end-user requirements – as gas detection users become increasingly aware of environmental and health impacts, along with the need to lower maintenance costs, many now specify long-life lead-free sensors as a key requirement in tender documents. Manufacturers without long-life options in their product range risk being excluded from bidding processes.
Easy integration – our latest lead-free sensor, the S+4OXLFF, achieves a zero-power start-up in under two minutes and requires no constant bias voltage. This extends battery life in portable instruments and reduces downtime during commissioning, servicing, and power outages for fixed-installation instruments.
