Vibration Sensor, Calibration or Verification?

Depends, but most can be calibrated with a vibration calibrator.

Ok.Only some of it.

Actually i have some vibration sensor bently nevada. And it need to be check whether those sensor still run as it function correctly or not. So i have another question here, should i calibrate it or just verification them is enough?

Thank You

Again, it depends- how critical is the vibration sensor. What's the $$ price to replace the equipment and or lives if this vibration sensor fails? Especially anything to do with turbines

If the equipment can self-destruct due to vibrations then it would to your best interest to either replace the sensor with a new one or send out to have it calibrated by a professional that has the proper calibration equipment and the knowledge to calibrate it. You should also stock 1 or 2 spares that are calibrated, so you minimize your down time due to failures.

It's your equipment, what's it worth to you?

Well, I'd have got on the phone to Bentley Nevada rather than coming here, then I'm funny that way.

Can you use a search engine, or is that a lost art?

TK3-2 Calibration Instrument - GE Measurement & Control

I'd call it verification, but I'm not an expert.

If there are basis inspite of the diffrence of maker, then it has a reference-standard. Look through the manual. What does the maker recommend? Some brand also has calibrator with higher accuracy than your field instrument or some will do calibration themselves. All you need to do is contact them.

@ dj95401

Thanks for answered my question again. Yeah it is mean to be installed on turbine. I think i will need the spare.

@Crabtree I agree with you, the thing is i cant find one in my country.

@lyn Yeah, thats what my senior said to me. It is verification not calibration.And thanks for the link.

@Kulas : Thanks for the information. I appreciate it much.

@Crabtree I agree with you, the thing is i cant find one in my country.

This is the age of globalisation. Find one in the USA. They also speak English...

I recall from many years ago, Bentley Nevada sensors being calibrated using what was then called a 'Wobulator' (also by Bentley Nevada)

there is no equipment to calibrate Vibration sensor, we only can check the health of vibration sensor. Adjustment can only be done in controler.

Can you elaborate on this? I am sitting on the fence here, but the first post said there is a calibration for vibration sensors.

If you can adjust something it can be calibrated, no?!

Maybe it's time to define vibration sensor.

I think of an accelerometer, when someone says vibration sensor.

I do not believe that accelerometers are adjustable.

A beginner's guide to accelerometers

There is a very simple procedure to CALIBRATE accelerometers.

First what is an accelerometer ? It is a mass+spring system and as we know every mass is subject to gravity. The usual procedure to calibrate to +/- 1g is to place the accelerometer with its sensitive direction on the vertical and then turn it 180 °. It will measure a difference of 2 g and the output should be + and - 1g depending on position.

For higher "g's" it is used a vibration table with frequency and amplitude control (2 servo loops). An other approach is to use a rotating table and impose a radial acceleration which is monitored by radius and rpm.

All are devices with an electronic amplifier so that calibration consists in modifying the GAIN so that the display corresponds to the imposed accelerations.

Then the accelerometer is not calibrated. The amplifier output is adjusted to account for the error of the sensor.

The term "vibration sensor", used in the title may be confusing, it is to me.

MEASUREMENT is a COMPARISON between a VALUE and a REFERENCE.

CALIBRATION is the "measurement" of a "device" output with respect to a REFERENCE which is TRACEABLE to the base REFERENCE for the measured value.

If the "device" has a variable part which does NOT change after setting it can be used in order to bring the "device" output in correlation to the reference.

This way are ,for instance, CALIBRATED all "weighing devices" (aka SCALES).

Your way to interpretate the "sensor" as only the mechanical part is wrong it is NOT possible to adjust the right way for instance a mem device. What would you do ? file the 0.05 mass or the corresponding 25 µm spring ?

The accelerometer has to be seen as a whole sensible element + amplifier. The force transducers in scales give, for instance, signals in the "mV" range so that an amplifier is requested.

According to your statement we should call you "Dynolyn" which would be a recognition to your DYNAMICS in answering all threads !

I think you just described a 'Wobulator'

I calibrate them all the time. They are a calibrated item.

Then, maybe it's time to define calibration.

Bently Nevada; uses two diffrent probes for viberation mesurment. accelerometer and Proximitor, acceleometer can not be calibrated only check for proper operation.

Proximitors can be calibrated, the gap voltage adjusted to the proper voltage.

If I mount the vibration pick up or accelerometer on my shaker table and shake it at a known level and sweep the frequency at that known level and observe the output compared to this vibration level isn't that a calibration?

If that's the standard you want to use.

What do you mean? That is the definition of calibration.

I agree with dj95401.

You have determined that the vibration pick up or accelerometer agrees with your shaker table. Calibration

How do you know if your shaker table is correct, unless it has been calibrated to an accepted standard?

You have verified that the two agree. Verification

When I worked on space junk, everything had to be traceable back to NBS.

Certainly. My standard accelerometer is cal'd at NIST. Of course that is part of calibration. That is how I know my shaker table is at the right vibration level. It is a given that calibration is done with standards that are more accurate than the UUT. I calibrate accelerometers, vibration pickups , displacement transducers, seismic probes, etc. on my shaker table using my standard accelerometer. Did it for the Air Force, NASA, and now for nuclear power.

OK then. That makes you the expert and me the dinosaur.

I think I am probably a dinosaur too.

Your post #21 is posed as a question, why? If you have all your certs' and cal tags current and up to date, then shouldn't be any question about your calibration abilities, right? I've dealt with the Arm Forces, NASA, NTSB, FAA etc. I know they like seeing tractability paperwork and those little stickers with dates and names and to what standards.

Of course. That IS calibration. Without traceability you are just pretending to calibrate. I am not quite sure what you are getting at. I know all of the traceability requirements as I have been a metrologist for 30 some years. You aren't telling me anything I don't know. To the OP, all of these vibration transducers are indeed able to be calibrated if desired.

http://en.wikipedia.org/wiki/Calibration

That I have to do that for you!

Ts ts.

Operation that, under specified conditions, in a first step, establishes a relation between the quantity values with measurement uncertainties provided by measurement standards and corresponding indications with associated measurement uncertainties (of the calibrated instrument or secondary standard) and, in a second step, uses this information to establish a relation for obtaining a measurement result from an indication."^[1]

Now fight!

No fight here.