These sensors are used for early detection of changes in vibrations of machinery. Early detection is critical in preventing damage to equipment and the results of costly delays. Vibration sensors can be used on motors, fans, pumps, moderate speed gearboxes, paper machine rolls, compressors and many more applications that use machinery on a daily basis.
Vibration sensors are key within the automotive and power generation industries and can be used in just about every industry process worldwide.
We have six sensors certified for use in Class I Division 2 (Zone 2) hazardous environments typically associated with the oil and gas, mining, steel, chemical processing, pharmaceutical, and petrochemical industries.
Class I Division 2 (Zone 2) general purpose accelerometers:
All sensors have a sensitivity of 100 mV/g, and a tight ± 5% sensitivity tolerance, and are certified for installation in Class I Division 2, Groups A,B,C,D E, F, G and Class I Zone 2 AEx na IIC T4.
The 780 series of narrow, low profile, and lightweight sensors are ideal for portable data collection and online monitoring. Compact size allows installation in small areas and easy handling on walk-around routes. Hermetic seal and piezo-stabilitation ensure a long sensor life and minimal signal drift, two of the quality and reliability traits for which Wilcoxon accelerometers are known for.
Sensitivity tolerance options
The series offers a variety of sensitivity tolerance choices. The 780A’s tight tolerance of ±5% is ideal for measurements on critical or failure prone machinery. The wider tolerances of the 780B (±10%) and 780C (±15%) offer an economical choice for vibration trending or walkaround programs in which the exact sensitivity tolerance of the sensor can be programmed into the acquisition system.
Many facilities want to monitor machinery vibration, but don’t want an “expensive” vibration program. 4-20 mA products keep track of vibration levels so that maintenance professionals can take action on machines that start trending upward (higher vibration).
The 786 series offers the longest MTBF rate in the industry providing continuous cost savings and reliable performance for 25 years.
Mean time between failures (MTBF) represents the average expected time that will elapse between failures of like units under like conditions. Purchasers should consider MTBF of sensors before buying them. Accelerometers with a low (short) MTBF result in higher costs due to the manpower required for troubleshooting, replacement of faulty accelerometers and lost data associated with the more frequent failures.
Total hybrid failure rate (λρ)
The Department of Defense developed a calculation to be used for electronic systems and circuits. Military Handbook MIL-HDBK-217 provides guidance for computing the MTBF for hermetically sealed electronic circuits.
The 786A is sealed to a leak rate of 1 x 10-8 cc/sec and is considered to be truly hermetically sealed. An analysis of failures indicates that the hybrid circuit board and connections are the only parts to fail due to normal environmental exposure. The piezoelectric sensing element does not play a significant role in failures.
λρ = [ΣNCλC] (1 + 0.2 πE) πF πQ πL failures per 1,000,000 hours
NC = number of each particular component
λC = failure rate of each particular component
πE = environmental factor
πF = hybrid function factor
πQ = quality (screening) factor
πL = longevity (experience) factor
N is determined from the part or connection count, all other factors are determined through reference to MIL-HDBK-217 for the particular component or element.
Calculated total hybrid failure rate of 786A
Total hybrid failure rate at 60° C
λρ = [0.064775] 70.18
= 4.5459 per 106 hrs
= 219,978 hours MTBF (25 years)
Total hybrid failure rate at 120° C
λρ = [0.230651] 70.18
= 16.187087 per 106 hrs
= 61,778 hours MTBF (7 years)
*1 - These Vibration Sensors are manufactured by Meggitt and sold by Yokogawa Corporation of America. All data is in accordance with manufacturer’s specifications and is subject to change and correction.
There are several factors for a user to consider when using an IEPE accelerometer, particularly when used with newly available integrated signal conditioner/data acquisition systems. Correctly managing these factors will help the user avoid erroneous data from their IEPE accelerometer and ensure the quality of the measurement data is at the level they expect and require.
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