We have some applications on intermittently running machinery that have become very difficult to monitor due to scheduling conflicts. (4-8hrs, 3 times per week running time at most)
I have been considering installing mini PLCs, such as a Micrologix or PICo, where an alarm would be generated if the acceleration exceeds a value (determined by existing trending). Also there are monitors such as the Entek "Sentinel" single channel Vibration Monitor.
This is also being considered for less critical applications, as a tool to trigger more detailed analysis, and to stretch monthly monitoring to quarterly.

Question:
What has been your experience with this type of monitoring?

Martin - we have hundreds of channels of monitoring with PLC's in Northern California - many using wireless communications. Our rep there are extremely knowledgeable vibration analyst and systems integrator. They may be reached to discuss your application at http://www.fastracktechnologies.com/.
You are also welcome to contact me directly.

Martin,

The "Sentinental" is a handy little bugger, used a lot in cooling tower applications.
If you have device net or similiar, check out the "XM" product from RockwellEntekIRD.
For trending, either one will work, but XM would require you have Odyssey Software for analysis. you can trend either one through panel view or similiar set up.

Dave

Vendor
We have made a new converter for standard accels that have 2x4-20mA output one for vibration and one for bearing condition, we also have a version that convert temp output from accels with temp sensor to 2x4-20mA 0-100DEG C so 3 converters give 6x4-20mA from 2 bearings. We have now delivered number 100 of this new version, previous single channel unit is delivered in several thousand with different input cards for velocity, accel, eddy probes. Olov

I need to make a distinction here.
I'm not talking about automatic periodic data sampling, and constant periodic analysis.

I am simply referring to an accelerometer used like any other analog input to a plc...as a device to create an alarm, which will trigger a more detailed analysis to be performed.

Do you use these devices in this manner?

IMI sells sensors that ouput 4-20 ma and which is equal to 0-.5 in/s (for instance). If the level exceeds .49 in/s, you have your alarm point with an ~ 19 ma current.

http://www.imi-sensors.com/420mAsensors/sensors.asp