High-temperature accelerometers specified for gas-turbine casing monitoring cluster in three OEM tiers: $413-$2,015 for piezoelectric charge-mode units rated to 649 °C, $1,955-$2,622 for extended-temperature (1200 °F / +649 °C) charge-mode sensors with $2622 list price for the 357B69, and $2,000+ for long-life PizeoStar-crystal units rated to 700 °C with a 3-5 year service life [S2][S4].
The cost driver is the sensing element class, not the brand: charge-mode piezoelectric crystals tolerate continuous 260-649 °C operation because they carry no built-in signal conditioning, while ICP-style built-in amplifier accelerometers are temperature-limited and rarely specified for hot turbine casings [S2]. For a deeper view of vibration-pickup fundamentals see the accelerometer reference page.
Price Tiers by Sensor Class
Charge-mode piezoelectric accelerometers dominate the high-temperature casing monitor market because their lack of onboard electronics removes the amplifier thermal ceiling that limits ICP units. PCB's published list for that family ranges from $413 for the 357B03 (10 pC/g, ±2000 g pk, 9 kHz) to $2,622 for the 357B69 (3.5 pC/g, ±500 g pk, 6 kHz), with the 357A63 listing at $1,955 (0.53 pC/g, ±5000 g pk, 10 kHz) and the 357C72 at $2,289 (50 pC/g, ±500 g pk, 2.5 kHz) [S2]. Charge-mode output requires an external charge amplifier or in-line charge converter, which is a separate line item and a real second cost driver [S2].
For permanent casing mounts where service intervals of 3-5 years at 700 °C are mandated, Kistler's PizeoStar-crystal piezoelectric accelerometer (made in Switzerland) is the published example: it is non-pyroelectric, exhibits no popcorn effect, and is rated for 700 °C long-term operation, with a 3-5 year lifespan figure cited in the product announcement [S4]. At the research end, silicon-carbide MEMS devices have been modeled and prototyped for blade-mounted, 1000 °C+ operation, but no commercial SiC high-temperature accelerometer is shown in current OEM catalogs [S1][S5].
Selection Criteria: Temperature, Sensitivity, Bandwidth
The four spec axes that actually move price are maximum continuous temperature, sensitivity (pC/g), measurement range (g pk), and resonant/bandwidth. Higher temperature tolerance is the single largest price multiplier: a 325 °C Metrix SA6350 industrial casing monitor (100 mV/g or 500 mV/g sensitivity) sits well below the 649-700 °C tier in cost [S3], while 700 °C-capable PizeoStar units command the $2,000+ bracket [S4]. Bandwidth is the secondary axis: a 10 kHz unit such as the 357A63 (0.53 pC/g, ±5000 g pk) lists at $1,955, while a 2.5 kHz high-sensitivity 50 pC/g unit (357C72) lists at $2,289, reflecting the trade between sensitivity and usable frequency range [S2].
For broad process-vibration context the temperature measurement and temperature monitor reference pages give the calibration and drift numbers a casing sensor has to survive next to. STI's CMCP700HT and PCB's EX600B1X (rated -65 to +900 °F / -54 to +482 °C) bracket the industrial mid-range between the 325 °C Metrix unit and the 700 °C Kistler PizeoStar line, and they are the typical choice where casings stay below 500 °C [S8][S9].
Cost Driver Breakdown
Material and crystal growth are the dominant per-sensor cost drivers. PizeoStar monocrystalline piezoelectric crystals, used in the Kistler 700 °C unit, are synthetic monocrystalline and were characterised as offering "great stability with no twinning and no phase transition up to the melting point, as well as high sensitivity and mechanical strength" in the 2011 ETC conference paper [S5]. The same paper notes the trade-off: conventional ceramic sensing elements show pyroelectric effects and popcorn noise at elevated temperature, so a non-pyroelectric monocrystal command a price premium at the same temperature class [S4][S5].
Certification and qualification are the second driver. Turbine-casing duty generally calls for an API 670-style seismic accelerometer form factor (the Metrix SA6200A is the explicit API 670 unit in the Metrix line, and the SA6350 high-temperature model shares that family geometry) and a hazardous-area rating where the casing is in a classified zone [S3]. Lead time and minimum-order quantity act as a third multiplier: PCB and Kistler both move many high-temperature models to "Add to cart for quote" status, indicating non-stocked, build-to-order supply rather than shelf inventory, which usually pushes effective per-unit pricing above list [S2][S6].
Use Cases: Casing, Bearing Housing, Combustion Liner
Casing- and bearing-housing-mounted accelerometers detect shaft-related vibration problems: bearing failures, misalignment, shaft cracks, structural resonance, unbalance, shaft bow, fluid-film and bearing instability, and rubs [S1]. That is the everyday API 670 pattern: a $400-$2,000 charge-mode or IEPE seismic sensor, 100-500 mV/g or 10-100 pC/g, mounted on the outer casing where skin temperature stays at 150-325 °C in most industrial gas turbines. The Metrix SA6350 (325 °C, 100 or 500 mV/g) is sized exactly for that envelope [S3].
Combustion-liner and burner-can monitoring is the harsh end. Modern gas turbines operate near the pulsation limit to meet emissions rules, so a pressure pulsation / vibration sensor sits inside the burner or combustion liner at 600-700 °C; PizeoStar-crystal sensors are specified for that location because conventional ceramics pyroelectric-noise or fail at those temperatures [S4][S5]. Blade-mounted direct measurement, by contrast, is still a research problem: a NASA / Army Research Laboratory finite-element study modelled a surface-micromachined 3C-SiC folded-beam lateral-resonating accelerometer, 2 µm SiC film on 500 µm (100) silicon, for blade-mount direct vibration measurement, but that is pre-commercial, not a catalog line [S1].
Comparison Matrix: Main Options
Lining the three practical options up against the decision criteria, from the OEM material available in the references:
Option A, mid-temperature charge-mode (260-500 °C): PCB 357A63 ($1,955), 0.53 pC/g, ±5000 g pk, 10 kHz; PCB EX600B1X family rated -54 to +482 °C; STI CMCP700HT at 100 or 500 mV/g [S2][S8][S9]. Best for: standard casing and bearing-housing mounts where skin temperature is below 500 °C. Not for: combustion-liner or burner-can duty.
Option B, extended charge-mode (500-649 °C / 1200 °F): PCB 357B69 ($2,622), 3.5 pC/g, ±500 g pk, 6 kHz; PCB 357C72 ($2,289), 50 pC/g, ±500 g pk, 2.5 kHz; PCB 357B03 ($413), 10 pC/g, ±2000 g pk, 9 kHz as a low-cost entry point [S2]. Best for: high-skin-temperature industrial and aero-derivative casings, steam-turbine and gas-turbine test cells [S2]. Not for: continuous 700 °C combustion monitoring.
Option C, PizeoStar long-life combustion (700 °C continuous, 3-5 year): Kistler high-temperature accelerometer, PizeoStar crystal, non-pyroelectric, no popcorn effect, made in Switzerland, 3-5 year service life at 700 °C [S4]. Best for: permanent combustion-dynamics monitoring in modern low-emissions gas turbines running near the pulsation limit. Not for: low-temperature bearing housings (cost penalty with no spec benefit).
Limitations, Failure Modes, Total Cost of Ownership
Failure modes follow temperature and signal-chain class. Charge-mode sensors without onboard electronics have no amplifier to fail at high temperature, but they require low-noise cabling and an external charge amplifier whose discharge time constant sets the low-frequency response [S2]. ICP-style accelerometers with built-in electronics are usually limited below 150-180 °C and are therefore not specified for hot casings [S2]. Pyroelectric and popcorn noise are the documented failure signatures of conventional ceramic piezoelectric elements at elevated temperature; the published Kistler PizeoStar specification is positioned specifically as a fix for those two failure modes [S4][S5].
Total cost of ownership for a casing channel is more than the sensor. A real line item is the charge amplifier or in-line charge converter per channel, plus high-temperature cable (rated for the local ambient) plus mounting hardware (Metrix 5497-series probe mounts, STI weatherproof/explosion-proof housings), plus the 3-5 year replacement cycle on the 700 °C PizeoStar unit, which doubles or triples sensor amortisation relative to a 325 °C industrial unit [S2][S3][S4][S8]. The relevant 2004 Power Engineering reference frame also notes that "inspecting a central station gas turbine for possible wear and tear costs about $500,000 in parts and labor," which puts a ceiling on what a permanent high-temperature sensor channel is worth: a single avoided tear-down pays for many sensors [S7]. On the duty-cycle side, a related data center BESS lead-time 2026 reference gives the parallel turbine-queue lead-time figure (up to 5 years) that explains why operators are willing to pay for permanent combustion monitoring rather than accept unscheduled outages.
Sourcing and Standards
Specifying a high-temperature accelerometer for a turbine casing starts with three documents: API 670 for the seismic-accelerometer form factor and channel architecture, ATEX/IECEx for hazardous-area rating on a gas-turbine package, and the OEM environmental specification for maximum continuous skin temperature at the proposed mount point. Casing-mount sensors in the 260-500 °C class are typically ordered against API 670, while 700 °C PizeoStar units in the combustor are usually project-spec engineered rather than off-the-shelf [S3][S4]. The 2011 ETC paper formally compares PizeoStar against conventional sensing materials for high-temperature pressure and accelerometer use, and it is the cleanest single sourcing reference for the materials trade-off [S5].
For engineering teams writing specifications, two practical filters narrow the list quickly. First, temperature: anything below 325 °C is the Metrix SA6350 and similar IEPE/industrial class; 325-500 °C is the PCB EX and CMCP700HT zone; 500-700 °C continuous is the PizeoStar / KI100-crystal tier [S3][S4][S5][S8][S9]. Second, signal chain: if the existing monitor accepts charge input directly, a 357-series charge-mode unit is the lowest-cost entry at $413 list; if it expects a low-impedance voltage output, plan a charge amplifier or in-line charge converter and budget the channel accordingly [S2].
Trackable signals to watch over the next two quarters: Kistler and PCB price-list refreshes on 357-series and PizeoStar part numbers, the next revision of API 670, and any product launch that moves a silicon-carbide MEMS high-temperature accelerometer from research to commercial catalog [S1][S2][S4].