- Email: [email protected]
PEEK performs for power plant probe
applications
PEEK performs for power plant probe RESISTANCE to high temperature steam has led to glass reinforced polyether etherketone (PEEK) being used in a probe for measuring water levels in power stations. A 30% glass reinforced grade of Victrex® PEEK™ was chosen over other materials for a critical part of the probe’s process seal, which prevents steam from reaching its internal components. Originally, the probe manufacturer had considered a seal design based on ceramic insulators brazed to metal components, but initial trials proved unsuccessful. The probe is used to measure water levels in systems such as boilers, de-aerators and feed water heaters where it has to operate under extreme heat
and pressure in a saturated steam environment. According to Victrex, PEEK has excellent hydrolytic stability and chemical resistance which enable it to perform in such harsh environments. The probe's seal is required to withstand high pressure loadings concentrated on a relatively small area. Service pressures can reach 110 bar at temperatures of 318°C. As a further function, the probe head has to transmit the electrical signal used to measure water levels. Victrex says the PEEK's relatively low dielectric constant allows the use of a small outer conductor. If a material with a higher dielectric constant had been used, the outer conductor would have
needed to be larger and may not have fitted within the design limits of the probe. The seal components are completely enclosed in stainless steel and all of the probe's parts are exposed to high temperatures. Because the PEEK has a thermal expansion coefficient similar to that of stainless steel, stresses caused by different rates of expansion are minimized. During development, a prototype of the probe was produced using an extruded PEEK rod. This eliminated the need to produce a mould before the design had been finalized. Now the probes are in full production, they are produced using injection moulding. Victrex plc; website: www.victrex.com.
PEEK meets the challenge of saturated steam environments.
RES No. 305 – USE THE FAST NEW ENQUIRY SERVICE @ www.reinforcedplastics.com
8
REINFORCEDplastics
January 2004
PEEK performs for power plant probe RESISTANCE to high temperature steam has led to glass reinforced polyether etherketone (PEEK) being used in a probe for measuring water levels in power stations. A 30% glass reinforced grade of Victrex® PEEK™ was chosen over other materials for a critical part of the probe’s process seal, which prevents steam from reaching its internal components. Originally, the probe manufacturer had considered a seal design based on ceramic insulators brazed to metal components, but initial trials proved unsuccessful. The probe is used to measure water levels in systems such as boilers, de-aerators and feed water heaters where it has to operate under extreme heat
and pressure in a saturated steam environment. According to Victrex, PEEK has excellent hydrolytic stability and chemical resistance which enable it to perform in such harsh environments. The probe's seal is required to withstand high pressure loadings concentrated on a relatively small area. Service pressures can reach 110 bar at temperatures of 318°C. As a further function, the probe head has to transmit the electrical signal used to measure water levels. Victrex says the PEEK's relatively low dielectric constant allows the use of a small outer conductor. If a material with a higher dielectric constant had been used, the outer conductor would have
needed to be larger and may not have fitted within the design limits of the probe. The seal components are completely enclosed in stainless steel and all of the probe's parts are exposed to high temperatures. Because the PEEK has a thermal expansion coefficient similar to that of stainless steel, stresses caused by different rates of expansion are minimized. During development, a prototype of the probe was produced using an extruded PEEK rod. This eliminated the need to produce a mould before the design had been finalized. Now the probes are in full production, they are produced using injection moulding. Victrex plc; website: www.victrex.com.
PEEK meets the challenge of saturated steam environments.
RES No. 305 – USE THE FAST NEW ENQUIRY SERVICE @ www.reinforcedplastics.com
8
REINFORCEDplastics
January 2004