CE281 444-281-000-111 Piezoelectric Accelerometer

The CE281 444‑281‑000‑111 is a premium piezoelectric accelerometer from Meggitt’s renowned vibro‑meter® product line, specifically engineered for industrial vibration monitoring in potentially explosive atmospheres where signal integrity over long distances, robust construction, and intrinsic safety are paramount. This Ex‑certified version features integrally attached electronics that perform on‑board charge‑to‑current conversion, eliminating the need for an external charge amplifier and providing a current‑modulated output that is inherently immune to cable capacitance and electromagnetic interference. Equipped with a rugged bayonet connector (MS3112E8‑3P), the CE281 444‑281‑000‑111 is designed for permanent installation in hazardous areas where flammable gases, vapours, or dusts may be present, offering both intrinsic safety (Ex ia) and non‑sparking (Ex nA) protection according to the most stringent international standards.

The sensor combines a centre‑mounted symmetrical shear‑mode piezoelectric element with integrally attached electronics housed in a hermetically sealed, all‑metal construction. The sensor head, flexible stainless‑steel protection tube, and electronics casing are welded together into a single leak‑tight assembly, providing absolute protection against cooling fluids, lubricants, water, steam, oil, salt‑spray, dust, fungus, and sand. This rugged design ensures decades of reliable operation in harsh and hazardous environments, including oil refineries, chemical plants, gas terminals, and offshore platforms.

The CE281 444‑281‑000‑111 delivers a nominal sensitivity of 10 μA/g, a dynamic measurement range from 0.0001 g to 200 g peak, and a frequency response of 3 Hz to 7000 Hz with a tolerance of <±5 %. Its high resonant frequency (25 kHz typical) ensures accurate 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 in hazardous area environments. This Ex version carries multiple international certifications, including ATEX (II 1 G Ex ia IIC T6…T2 Ga and II 3 G Ex nA IIC T6…T2 Gc), IECEx, CCSAus (Class I, Division 1 & 2, Groups A‑D; Class I, Zone 0 & 2), KGS, and TR CU (Russian Federation), making it suitable for global deployment in Zone 0, 1, and 2 classified areas, as well as Division 1 and 2 locations in North America.

This product introduction provides a comprehensive description of the CE281 444‑281‑000‑111, 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 (CE281‑011, 2021) and reflects the company’s commitment to engineering excellence, safety, and customer support in extreme environments.

Key Features and Benefits

Ex Certified for Hazardous Areas – The CE281 444‑281‑000‑111 is approved for use in potentially explosive atmospheres with multiple certifications: ATEX (II 1 G Ex ia IIC T6…T2 Ga and II 3 G Ex nA IIC T6…T2 Gc), IECEx (Ex ia IIC T6…T2 Ga and Ex nA IIC T6…T2 Gc), CCSAus (Class I, Division 1 & 2, Groups A‑D; Class I, Zone 0 & 2; AEx ia/nA IIC T6…T2 Ga/Gc), KGS (Ex ia IIC T6…T2), and TR CU (0Ex ia and 2Ex nA IIC T6…T2 Ga/Gc). This ensures global compliance and safe operation in the most demanding applications.

Integrally Attached Electronics – The built‑in charge‑to‑current converter eliminates external signal conditioners, reducing system cost and complexity. The current‑modulated 2‑wire output is inherently immune to cable capacitance and noise, enabling long‑distance signal transmission without degradation – a critical feature in large industrial plants.

Hermetically Welded All‑Metal Construction – The sensor head, flexible stainless‑steel protection tube, and electronics casing are welded into a single leak‑tight assembly, impervious to 100 % relative humidity, water, steam, oils, salt‑spray, dust, fungus, and sand. This ensures decades of reliable operation in harsh and hazardous environments without risk of contamination ingress.

Wide Temperature Range – The sensor head operates from –55 °C to 260 °C continuously (short‑term survival to 290 °C), while the electronics function from –40 °C to 125 °C, making the sensor suitable for high‑temperature machinery monitoring in hazardous areas, such as gas turbines and compressors.

High Sensitivity and Wide Dynamic Range – With 10 μA/g ±5 % sensitivity 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 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 (MS3112E08‑3S). This simplifies field replacement and cable routing in hazardous areas.

Factory Calibration – Dynamic calibration at 120 Hz and 5 g peak ensures accuracy from delivery; no subsequent calibration is required under normal use, reducing maintenance costs.

Global Approvals – CE marked, EAC certified, RoHS compliant, and meets EN 61000‑6‑2, EN 61000‑6‑4, and EN 61010‑1 standards, ensuring suitability for worldwide industrial applications in hazardous zones.

Applications

The CE281 444‑281‑000‑111 is ideally suited for vibration monitoring in hazardous areas and harsh industrial environments, including:

• Oil and Gas Industry – Monitoring of compressors, pumps, turbines, and reciprocating machinery in refineries, gas processing plants, and offshore platforms where flammable gases are present and Ex ia/Ex nA protection is required.

• Chemical and Petrochemical Plants – Surveillance of reactors, mixers, centrifuges, and fans in Zone 0, 1, and 2 classified areas where explosive vapours or dusts may occur.

• Power Generation – Vibration measurement on gas and steam turbines, generators, and auxiliary equipment in co‑generation and thermal power plants with potential explosive atmospheres.

• Mining and Minerals Processing – Monitoring of crushers, mills, conveyors, and ventilation fans in coal‑handling and mineral processing facilities where dust explosions are a risk.

• Pharmaceutical and Food Processing – Vibration monitoring in solvent‑handling areas and dust‑explosive environments where intrinsic safety is mandatory.

• Marine and Offshore – Propulsion systems, deck machinery, and cargo pumps on tankers and FPSO vessels operating in hazardous zone classifications.

• Hazardous Area Test and Measurement – Temporary or permanent installations for performance validation and predictive maintenance in Ex‑classified zones.

Detailed Description of the Ex Bayonet Version (444‑281‑000‑111)

The CE281 444‑281‑000‑111 is the Ex‑certified variant of the legacy CE281 family, equipped with a bayonet connector (MS3112E8‑3P) and approved for installation in potentially explosive atmospheres. This sensor is designed to meet the stringent requirements of IEC 61508 for functional safety and ATEX directives for equipment in hazardous areas. The Ex certification covers both intrinsic safety (Ex ia) for Zones 0, 1, and 2, and non‑sparking (Ex nA) for Zone 2, providing flexibility for different hazardous area classifications. This dual certification allows the same sensor to be used across a wide range of Ex zones, simplifying inventory and reducing engineering complexity.

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 – a critical advantage in large industrial complexes where sensors may be located far from monitoring panels.

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 444‑281‑000‑111 suitable for installations where the cable must be routed through tight spaces or moving parts in hazardous zones.

The electronics housing contains all the signal conditioning circuitry, including the charge‑to‑current converter, voltage regulator, and output driver. For Ex installations, the electronics are designed with intrinsic safety barriers that limit the energy available to the sensor, preventing ignition of explosive atmospheres. The housing 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 bayonet connector (MS3112E8‑3P) is made of stainless steel and provides a quick‑connect, positive‑locking interface. The bayonet coupling mechanism ensures a secure vibration‑resistant connection while allowing easy cable replacement or sensor change‑out without tools. For Ex applications, the mating connector and cables must be of approved types (e.g., CG134 bayonet connectors with appropriate Ex certification) to maintain the integrity of the safety system. The wiring must adhere to the specific parameters provided in the Ex certificates, including maximum voltage, current, and capacitance limits. Note that pins B and C of the bayonet connector must be connected together externally (as shown in the wiring diagram) – this is typically done in the mating connector or junction box.

The CE281 444‑281‑000‑111 is dual‑certified for Ex ia and Ex nA, meaning it can be used in Zone 0 (continuous explosive atmosphere) with intrinsic safety barriers, as well as Zone 2 (occasional explosive atmosphere) with non‑sparking protection. The temperature classification T6…T2 covers a wide range of ignition temperatures, with the actual T‑code depending on the ambient temperature and the specific model parameters. For precise T‑code and special conditions for safe use, refer to the individual Ex certificates (KEMA 04 ATEX 1055, IECEx DEK 15.0029, etc.) available from Meggitt.

This legacy series version (ending in 111) is the predecessor to the later 113 variant, with identical mechanical and electrical performance but older ordering codes. The CE281 444‑281‑000‑111 is the direct Ex bayonet replacement for the earlier 112? Actually 011/111/211 are legacy; 013/113/213 are updated. The CE281 444‑281‑000‑111 remains fully interchangeable with later versions and is still supported for existing systems.

Installation and Mounting Guidelines

Proper installation is essential to achieve the specified performance and maintain the Ex certification of the CE281 444‑281‑000‑111. The following guidelines are based on Meggitt’s recommended practices and the requirements of the applicable Ex certificates:

• 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 – Ex ia Intrinsic Safety – For Ex ia installations, the sensor must be connected through an approved galvanic separation unit (e.g., GSI127) or an intrinsically safe barrier that limits the voltage and current to the levels specified in the Ex certificate. The supply voltage must be within 15 to 28 VDC, and the bias current between 5 and 8 mA. The cable capacitance and inductance must be within the permissible limits to avoid spark ignition. The bayonet connector pins B and C must be connected together externally. Only use approved Ex‑certified cables and connectors (e.g., CG134 bayonet connectors with appropriate certificate, using K210 cable) to maintain the safety integrity.

• Electrical Connections – Ex nA Non‑sparking – For Ex nA installations, the same basic electrical parameters apply, but the barrier requirements are less stringent. However, all wiring must be done according to the Ex nA certificate conditions, including the use of suitable cable glands and enclosures to prevent sparking during normal operation. Still, connection of pins B and C externally is required.

• 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, for Ex installations, the shielding and grounding must be performed according to the Ex certificate requirements, typically involving connection to a protective earth at the control panel. Follow the guidelines in the installation manual for CExxx and PVxxx vibration sensors and the specific Ex documentation.

• 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 – Installation must be carried out by competent personnel trained in Ex practices. All wiring, cable glands, and junction boxes must comply with local regulations and the relevant Ex standards. The sensor and its associated cables must be protected from mechanical damage and chemical attack. Regular inspection and maintenance as per the plant’s safety procedures are mandatory.

• Commissioning – Before energising, verify that all connections are correct and that the Ex barriers or separation units are properly installed. Perform a functional test using a known vibration source to confirm sensitivity and output current. Record the bias current and signal levels for future reference.

Commissioning and Verification

After installation, the CE281 444‑281‑000‑111 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. In Ex installations, ensure that the barrier or isolation unit is functioning within its specified parameters.

Ordering Information

The CE281 444‑281‑000‑111 is ordered using the following designation:

When ordering the CE281 444‑281‑000‑111, specify the required cable length (if factory‑assembled with a specific length; consult Meggitt for custom lengths). Also indicate any special requirements for the Ex certificate (e.g., T‑code, specific gas group). The Ex certificate documentation (ATEX, IECEx, etc.) is provided with the product upon request.

Accessories

A range of accessories is available to complement the CE281 444‑281‑000‑111, facilitating installation, cable extension, and system integration in hazardous areas:

Note: When ordering cable assemblies or connectors for the CE281 444‑281‑000‑111, ensure they are certified for use in hazardous areas and compatible with the bayonet connector (MS3112E8‑3P). The mating connector is the CG134 bayonet type (MS3112E08‑3S) with appropriate Ex certification (e.g., for use with K210 cable). Always refer to the Ex certificates for the specific safety parameters (maximum voltage, current, capacitance, inductance) of the entire loop.

Disposal and Environmental Compliance

At the end of its service life, the CE281 444‑281‑000‑111 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.