CE281 444-281-000-012 Piezoelectric Accelerometer

The CE281 444‑281‑000‑012 is a high‑performance piezoelectric accelerometer from Meggitt’s renowned vibro‑meter® product line, distinguished by its integrally attached electronics that perform on‑board charge‑to‑current conversion. This standard version, equipped with a rugged bayonet connector, is specifically designed for long‑term industrial vibration monitoring in demanding environments where signal integrity over extended cable runs, reliability under harsh conditions, and ease of installation are paramount. The CE281 444‑281‑000‑012 combines a centre‑mounted symmetrical shear‑mode sensing element with built‑in signal processing, eliminating the need for an external charge amplifier and providing a current‑modulated output that can be transmitted over long distances without degradation.

The sensor head and the electronics housing are interconnected by an integral, low‑noise shielded cable, hermetically sealed within a flexible stainless‑steel protection tube. The entire assembly—sensor head, protection tube, and electronics casing—is hermetically welded to create a fully leak‑tight system that is impervious to cooling fluids, lubricants, water, steam, oil, salt‑spray atmospheres, dust, fungus, and sand. This rugged construction makes the CE281 444‑281‑000‑012 exceptionally reliable for permanent installation in industrial environments such as power generation, petrochemical plants, paper mills, steel works, and marine applications.

The CE281 444‑281‑000‑012 offers a nominal sensitivity of 10 μA/g, a wide dynamic measurement range from 0.0001 g to 200 g peak, and a frequency response of 3 Hz to 7000 Hz within ±5 %. Its high resonant frequency (25 kHz typical) ensures faithful capture of high‑frequency vibration components, including gearmesh and blade‑pass frequencies. The sensor head operates continuously from –55 °C to 260 °C, while the electronics are rated for –40 °C to 125 °C, accommodating a broad spectrum of industrial processes.

The bayonet connector (MS3112E8‑3P) provides a secure, quick‑connect interface that mates with standard CG134 bayonet connectors (MS3112E08‑3S), simplifying installation and maintenance. The standard version (ordering number 444‑281‑000‑012) is designed for non‑hazardous area applications, though Ex‑certified variants are also available for potentially explosive atmospheres.

This product introduction provides a comprehensive description of the CE281 444‑281‑000‑012, including key features, applications, detailed technical specifications in tabular form, installation guidelines, ordering information, and available accessories. All information is derived from the official Meggitt data sheet (2021) and reflects the company’s commitment to engineering excellence and customer support.

Key Features and Benefits

Integrally Attached Electronics – The built‑in charge‑to‑current converter eliminates the need for an external signal conditioner, reducing system cost, complexity, and maintenance. The current‑modulated output (2‑wire system) is immune to cable capacitance and noise, enabling signal transmission over long distances without loss of fidelity.

Hermetically Welded All‑Metal Construction – The sensor head, flexible stainless‑steel protection tube, and electronics housing are welded together into a single leak‑tight assembly. This provides absolute protection against moisture, oils, chemicals, steam, and particulate ingress, ensuring decades of reliable operation in harsh industrial environments.

Wide Temperature Range – The sensor head operates from –55 °C to 260 °C continuously (with short‑term survival to 290 °C), while the electronics function from –40 °C to 125 °C, making the CE281 444‑281‑000‑012 suitable for high‑temperature machinery monitoring, including gas turbines, compressors, and pumps.

High Sensitivity and Wide Dynamic Range – With a sensitivity of 10 μA/g ±5 % and a measurement range from 0.0001 g to 200 g peak, the sensor captures both low‑level bearing vibrations and high‑amplitude imbalance events. Overload capacity up to 2000 g peak protects against shock transients.

Excellent Frequency Response – A flat response of ±5 % from 3 Hz to 7000 Hz, combined with a typical resonant frequency of 25 kHz, enables accurate measurement of both low‑speed machinery dynamics and high‑frequency gear and bearing defects.

Integral Case Insulation – Both the sensor element and electronics are insulated from their housings, preventing ground loops and simplifying installation without the need for electrically isolated mounting surfaces.

Low Transverse Sensitivity – Transverse sensitivity is less than 3 % at 15 Hz with 5 g, ensuring that the sensor responds predominantly to the intended measurement axis, minimising cross‑axis interference.

Rugged Bayonet Connector – The standard MS3112E8‑3P bayonet connector provides a secure, vibration‑proof, and quick‑release interface, compatible with widely available CG134 mating connectors. This simplifies field replacement and cable routing.

Long‑Term Stability – Factory dynamic calibration at 120 Hz and 5 g ensures accuracy from delivery; no subsequent calibration is required under normal use, reducing maintenance costs.

Applications

The CE281 444‑281‑000‑012 is ideally suited for a wide range of industrial vibration monitoring applications, including:

• Gas and Steam Turbines – Continuous monitoring of bearing housing, casing, and shaft vibration in power generation and mechanical drive applications.

• Centrifugal and Axial Compressors – Vibration surveillance to detect imbalance, bearing wear, and surge conditions in oil & gas, chemical, and refrigeration plants.

• Pumps and Fans – Long‑term condition monitoring of critical rotating equipment in water treatment, HVAC, and process industries.

• Paper and Steel Mills – Harsh environment monitoring of rollers, calenders, and continuous casting machinery where moisture, dust, and high temperatures are prevalent.

• Marine and Offshore – Vibration measurement on propulsion systems, deck machinery, and auxiliary equipment subject to salt‑spray and high humidity.

• Test and Measurement – Temporary and permanent installations for performance validation, troubleshooting, and predictive maintenance programmes.

• Non‑Hazardous Industrial Areas – The standard version CE281 444‑281‑000‑012 is suitable for general industrial environments where explosive atmospheres are not present. For hazardous areas, Ex‑certified versions (444‑281‑000‑112 and 444‑281‑000‑212) are available.

Detailed Description of the Standard Bayonet Version (444‑281‑000‑012)

The CE281 444‑281‑000‑012 represents the standard, non‑Ex variant of the CE281 family. It is equipped with a bayonet connector (MS3112E8‑3P) that provides a quick‑connect, positive‑locking interface. This connector is made of stainless steel and is designed for industrial environments where rapid installation and disconnection are beneficial. The bayonet coupling mechanism ensures a secure vibration‑resistant connection while allowing easy cable replacement or sensor change‑out without tools.

The sensor’s internal architecture consists of a centre‑mounted symmetrical shear‑mode piezoelectric element made of polycrystalline material. This design offers excellent stability, low transverse sensitivity, and high resistance to base strain and temperature transients. The integrally attached electronics convert the charge generated by the piezoelectric element into a proportional current signal. The current‑modulated output (2‑wire system) carries both power to the sensor and the signal from the sensor over the same two conductors, simplifying cabling and reducing installation costs. Because the output is a current signal, it is largely insensitive to cable capacitance and electromagnetic interference, permitting cable runs of several hundred metres without signal attenuation or degradation.

The entire measurement chain from the sensing element to the connector is protected by a hermetically sealed mechanical construction. The sensor head is welded to a flexible stainless‑steel protection tube (1.4541), which in turn is welded to the electronics housing (1.4441). This continuous welded assembly ensures that no moisture, oil, or contaminants can penetrate the internal components. The protection tube is designed to withstand repeated flexing and mechanical stress, making the CE281 444‑281‑000‑012 suitable for installations where the cable must be routed through tight spaces or moving parts.

The electronics housing contains all the signal conditioning circuitry, including the charge‑to‑current converter, voltage regulator, and output driver. It is rated for operation up to 125 °C, which is adequate for most industrial applications where the electronics can be mounted remotely from the hot sensor head. The sensor head, rated to 260 °C, can be placed directly on hot machinery surfaces, while the electronics can be located in a cooler area, thanks to the flexible cable length (specified at order). This separation of thermal zones extends the overall system life and reliability.

The standard version does not carry Ex certification, making it suitable for use in non‑hazardous areas. For applications in potentially explosive atmospheres, the Ex versions (444‑281‑000‑112 with bayonet connector and 444‑281‑000‑212 with threaded connector) provide intrinsic safety (Ex ia) or non‑sparking (Ex nA) protection and are certified to international standards (ATEX, IECEx, CCSAus, KGS, TR CU).

Installation and Mounting Guidelines

Proper installation is essential to achieve the specified performance from the CE281 444‑281‑000‑012. The following guidelines are based on Meggitt’s recommended practices:

• Sensor Head Mounting – The sensor head is secured using three M4×16 Allen bolts and three M4 spring‑lock washers. The recommended tightening torque is 4.5 Nm (3.3 lb‑ft). The mounting surface should be flat, clean, and free from burrs or paint to ensure full contact and consistent preload. For optimal high‑frequency response, a surface finish of 1.6 µm (63 µin) or better is recommended.

• Electronics Casing Mounting – The electronics housing is mounted using four M6×35 Allen bolts with M6 spring‑lock washers, torqued to 15 Nm (11.1 lb‑ft). The casing can be attached to a bracket, panel, or machine structure. Ensure that the mounting surface is rigid to avoid relative motion between the casing and the sensor head, which could induce cable stress.

• Cable Routing – The flexible protection tube should be routed with a bend radius that avoids kinking or crushing. While a specific minimum bend radius is not stated in the data sheet, general practice for similar stainless‑steel hoses is to maintain a radius of at least 50 mm (2 in). Secure the cable at regular intervals using P‑clips or cable ties, but avoid over‑tightening that could deform the hose. Do not subject the cable to repeated flexing at the same point, as this could cause fatigue.

• Electrical Connections – The bayonet connector (MS3112E8‑3P) mates with a CG134 bayonet connector (MS3112E08‑3S). The standard version does not require special wiring for Ex barriers. However, for proper operation, the power supply must provide 15 to 28 VDC and supply a bias current of 5 to 8 mA. The two‑wire interface carries both power and signal; connect the positive supply to one pin and the return/signal to the other. Note that for the bayonet connector, pins B and C must be connected together externally (as shown in the wiring diagram) – this is typically done in the mating connector or junction box.

• Grounding and Shielding – The integral case insulation means that neither the sensor head nor the electronics casing is electrically connected to the signal ground. This prevents ground loops. However, proper grounding of the cable shield and the electronics housing is recommended to minimise electromagnetic interference. Follow the guidelines in the installation manual for CExxx and PVxxx vibration sensors.

• Thermal Considerations – Ensure that the sensor head is used within its specified temperature range. If the sensor head is mounted on a surface exceeding 260 °C, use a thermal insulation kit (MA133) or a mounting adaptor (TA102, TA104) to reduce heat transfer. The electronics housing must be kept below 125 °C; if ambient temperatures are higher, provide forced cooling or relocate the housing to a cooler zone.

• Hazardous Area Precautions – Although this standard version is not Ex‑certified, it may still be installed in non‑classified areas. For any installation near flammable materials, always consult local safety regulations and use appropriate Ex‑certified versions.

Commissioning and Verification

After installation, the CE281 444‑281‑000‑012 should be verified using a known vibration source or a portable calibrator. The output current should be proportional to the applied acceleration; a sensitivity check can be performed by applying a known g‑level and measuring the current change. The bias current should be within 5 to 8 mA when no vibration is present. Additionally, verify that the connector mating is secure and that the shield continuity is intact. For long‑term monitoring, periodic system checks (e.g., during routine maintenance) are recommended to ensure the sensor and electronics are functioning correctly.

Ordering Information

The CE281 444‑281‑000‑012 is ordered using the following designation:

When ordering the CE281 444‑281‑000‑012, specify the required cable length (if factory‑assembled with a specific length, although the integral cable length is fixed at manufacture; consult Meggitt for custom lengths). For the standard version, no Ex certificate documentation is required. However, if the sensor is to be used in a system requiring CE or EAC compliance, the product already meets these standards.

Accessories

A range of accessories is available to complement the CE281 444‑281‑000‑012, facilitating installation, cable extension, and system integration:

Note: When ordering cable assemblies or connectors, ensure compatibility with the bayonet connector of the CE281 444‑281‑000‑012 (MS3112E8‑3P). The mating connector is the CG134 bayonet type (MS3112E08‑3S). For Ex applications, use only certified connectors and cables as specified in the relevant Ex certificate.

Disposal and Environmental Compliance

At the end of its service life, the CE281 444‑281‑000‑012 should be disposed of in accordance with local environmental regulations. The sensor contains INCONEL alloy, stainless steel, and electronic components. In the European Union, the Waste Electrical and Electronic Equipment (WEEE) Directive applies – separate collection and recycling are mandatory. Meggitt supports environmentally responsible disposal and can advise on proper recycling channels.