28 Aug 2001
Sensors made with VICTREX® PEEK polymer can monitor a broad range of acidic and caustic applications
Quantum Analytical Instruments, Inc., a subsidiary of Racine Federated Inc., located in Racine, Wisconsin, USA, have specified VICTREX® PEEK™ polymer, for the sensor housing and structural components of analytical sensors to be used in a broad range of process measurement applications. Quantum Analytical's new line of sensors is designed for continuous monitoring of pH, Oxidation-Reduction Potential (ORP), Conductivity and Dissolved Oxygen in all industrial process control, as well as municipal and environmental monitoring applications.
Victrex PEEK™ polymer, a high-performance engineering thermoplastic, was chosen because of its outstanding combination of properties. “PEEK™ polymer is the one material that can be used across the board in the harshest environments,” says William J. Popp, Manager of Marketing and New Business Development at Quantum Analytical. “Its unique combination of mechanical and chemical properties allows us to offer one product that can be used in both acidic and caustic applications, ranging from potable water and chemical feed to wastewater and food processing.”
Chemical resistance is a major property requirement for the sensor body and structural components. “Traditional sensors commonly use materials such as LCP and PPS," explains Popp. "However, each of these materials has a limited chemical resistance. For example, LCP can withstand chemical attack in acidic applications, but this material is dissolved in hot, caustic applications. Conversely, PPS is usually the material of choice for sensors used in caustic environments but it is not recommended for acidic applications.
Many times a customer has both acidic and caustic processes in the same plant which means the customer must carry two different types of sensors. More importantly, the customer must take great care not to install the wrong sensor in each of the process lines. But because of its superior chemical resistance, the sensors made of PEEK™ polymer can be used in either application, thereby eliminating the need for multiple sensor types and preventing sensor misapplication."
Another important feature of PEEK™ polymer is its outstanding mechanical strength. Sensors are frequently used in process applications with high-suspended solids concentrations. A sensor operating in this type of environment requires very high mechanical strength because the housing is continuously being impacted by some type of solid. The mechanical strength of other polymers, such as LCP, comes from the polymer's chemistry at the surface of the part. Any abrasion by suspended solid or machining of the part can weaken the material structure. The mechanical strength of PEEK™ polymer, however, is derived from the polymer's internal chemistry. PEEK™ polymer can be abraded or modified without appreciable loss of its mechanical strength.
Temperature stability is also an important factor. In certain applications there are large temperature transients which are a normal part of the process application. The temperature of the process may start out at, or below, room temperature, but is then heated and cooled as part of the manufacturing process. Over time, the sensor is subjected to repeated temperature cycles. When a sensor is constructed of many different materials, changes in temperature cause the parts to expand and contract at different rates, or not return to their original dimensions. This means that the integrity of the sensor seals tends to degrade over repeated temperature cycles, which can open a leak path into the sensor and render it non-functional. “But because the housing and structural components in our new line of sensors are made with PEEK™ polymer,” says Popp, “they have the same coefficient of thermal expansion. The parts expand and contract at the same rate so the integrity of the sensor seals is not compromised over repeated temperature cycles."
An additional feature of the Quantum Analytical sensors is the encapsulation of the internal electronic components. A critical requirement for this feature is the a
Reader enquiries
Helen SwarbrickVictrex plc
Victrex Technology Centre
Hillhouse International
Thornton Cleveleys
Lancashire FY5 4QD
United Kingdom
Tel +44 1253 897700
Fax +44 1253 897701
United Kingdom
Notes for editors
Victrex plc, which has its sales, technical and production headquarters at Thornton Cleveleys in Lancashire, UK, had a turnover of more than £58m in the last financial year. The company exports 98 percent of its VICTREX® PEEK™ polymer output to OEMs in the automotive, industrial, medical, food and electronics market sectors in Europe, North America and Asia Pacific.
Information on products, technical support services and sales and distribution contacts worldwide, can be accessed through the company’s web site: www.victrex.com
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The PEEK™ Trademark
For many years Victrex plc has been using the PEEK™ trademark to refer to its brand of Polyaryletherketone. Victrex plc is the sole manufacturer and supplier of the PEEK™ brand polymer world-wide. PEEK™ is a trademark of Victrex plc.
Related images
Quantum Analytical chose Victrex PEEK™ polymer because of its unique combination of mechanical and chemical properties that allows one product to be used in both acidic and caustic applications, ranging from potable water and chemical feed to wastewater and food processing.
