Handling  As stated above, dropping a sensor on a concrete surface from waist level or higher will almost always damage it. Dropping accounts for the majority of sensor failures. Take care to keep a tight grip on the sensor when carrying it from the case to the point of application. If climbing a maintenance stand or ladder, put the sensor in your pocket until your are positioned for installing the sensor. Some sensors are delivered in heavy foam cubes and are usually small enough to carry in one hand. The heavy foam offers good protection against most damage caused from dropping.

Environment Most modern design sensors are hermetically sealed against the elements. This means the sensor can be submerged in shallow liquid without damage. Or does it? What if that liquid is corrosive? The most likely victim of such a bath would be the small connector pins. If not destroyed, they may loose the ability to effectively conduct the electrical signal. Excessive heat can destroy the sensor from inside even if the external appearance is completely normal. Directly on top of the piezoelectric element is the mass and atop that are small electronic components that will virtually melt in high temperature applications, especially with turbine engines. Check the temperature rating on the data sheet for your sensor before attempting to use it for hot section surveys or two plane balance applications where the second sensor must be placed in or near the hot section.

Connections The second most common type of damage to sensors is caused from improperly attaching cables or attaching the wrong cable to a sensor. Always check the connecting pins to make sure they are not bent or pushed in. Failure of the pins to make proper contact with the cable connector will render the sensor useless. Although the cable connector appears to be the correct one, always check the cable prior to connecting it to the sensor to make sure the number of pins and connector type match. Be sure that the cable you are using was designed for the sensor you are using. Even if the number of pins or sockets match, the wiring may be sufficiently different to cause damage to the sensor. Check part numbers and attached labels to make sure the correct cable is being used.

Verification   Although most modern sensors can’t be calibrated, on a routine basis they should be verified as being within tolerance. When sending your analyzer in for calibration, send everything. The calibration cost covers a check of all the accessories including the vibration sensors. The sensor is attached to a calibrated shaker that vibrates the sensor at a precise frequency and amplitude. The output of the sensor is then checked to make sure it is within the tolerance set by the manufacturer. In addition to having the sensor checked annually, you should also have it checked anytime it is suspect due to possible damage or questionable operation. As an interim check, if you have a second sensor, exchange the one in question and repeat the test. Of course, if you have questions about both, a calibrated test is the only way to verify whether you have a reliable sensor or a very expensive fishing weight.