Accelerometers

[shantanu@india]

Hi,
I need to measure pump vibration in three axes, or one axis if price is too high.
Any cheap solution to measure 0-25 mm/sec velocity?

[trastikata]

Hello shantanu,

it depends what is the maximum expected frequency, temperature, size of the pump, i.e. how is the pump mounted etc.

[shantanu@india]

Hi Trastikata,
These are horizontal & vertical split case pumps running 24 X 7 mainly in sewage & water supply duties.We are planning to integrate condition monitoring as a standard feature for all our pumps except fire pumps.

[shantanu@india]

Under standard operating conditions I expect the bearing housing temperature would not exceed 50 degrees celcius.

[ken_k]

Hi Shantanu I'm certain these days there would be a suitable MEMS devices, about 30 years ago I successfully used some ceramic bimorph devices I was able to solder them directly to a PCB in the required direction, they are very cheap with a high output, one needs to watch the resonant frequency, maybe not what you are looking for, they are however interesting devices one could use a single opamp as a peak detector then ADC or Hi z input buffer direct into a fast ADC.
https://au.rs-online.com/web/p/vibration-sensors/1704382

also
RS part number 285-784

[shantanu@india]

Hi Ken,
Talking to you after ages...
Yes low cost mems devices are all over the online shopping places.. have to select carefully.
The one you posted is cantilever which I cannot mount on a pump body unless I take recourse to an independent non- vibrating body. I think mems sensors are to be used.
Pumps work in hedious environmental conditions and the main trick is to save the sensors from damage

[trastikata]

Low cost MEMS accelerometers barely have 3KHz bandwidth - if that is enough you will have to take into consideration the RPM and the number of vanes in the propellers. Then might suit you, but also software for FFT analysis will be needed to get the frequencies and the amplitudes..

[shantanu@india]

Yes... let me buy some and compare values with Bruel and Kjaer