We use audio headphones while collecting data and have some newbies wondering about what certain problems will sound like.

Anyone out there have audio of known vibration problems that they could either post or send to me?

Is there a way to get time waveform data out of RBMWare and play it somehow?

I'm not sure but I think that you can import it to MEScope and play it there. To hear what different frequencies sound like you can go to http://www.falstad.com/fourier/ and play the sound of mixed or single frequencies.

Mike, I have an MP3 player (Zen Nano Plus) that has a line-in jack. I can record the output from the headphone adapter. It automatically encodes to MP3 at a selectable bit rate and you can drag-and-drop the files to your PC. (The PC 'sees' the player as a disk drive when you connect it.) Works great... I just haven't had the time to record anything in any sort of organized way.

This player is available (or used to be) at Wal-Mart for < $100.

Zen Nano Plus MP3 player/recorder

Loud! Causing hearing problems - liability. Modulation, demodulation and calibration may be a problem. My hearing has suffered enough already just listening to analyzers. I can't see such as an effective tool - could be wrong but when my son stepped into the motorhome complaining about the loud noise and asking how can you stand that - I said, What? Go find it and turn it off - fire alarm was going off. The step of amplitude in frequency bands from my hearing test aren't even close to an 'A' filter.

Listening to vibration data is an extrremely effective way at diagnosing problems. It turns out that the things the FFT is best at, like finding a 1x peak indicating imbalance aren't so easily diagnosed by ear, but the things that the FFT is less effective at, like detecting bearings in early deterioration stage, the ear is wonderful at.

A couple interesting examples come up from some of my sonar testing in the past. One of our guys was looking at the analyzer, puzzling over some noise that had appeared. After about 2 or 3 minutes of looking at different frequency ranges and different locations, he asked me what I thought it was. I put on the headphones that were right there and immediately told him to hang on, just as the work boat bumped into us. I'm sure an experienced sonar technician could have looked at the vibration signature and told us how many blades the propeller had, how fast the engine was turning, etc...but 5 seconds of listening was enough to determine that the noise was the propeller sounds of the small work boat.

Just don't crank the volume up! As Sam warns, ear protection is really important and should be worn in almost any area where we're testing machinery!

Jon
Spintelligent Labs

The headphone adapter that we use with the CSI 2120 or 2130 has a 'volume' knob for adjusting output. I usually turn it down to where I can just hear a "good" bearing; when I hear one that is not good, I can tell immediately.

Also, when you turn the meter on, if the accel is powered (normally it is), you get output regardless of the setting for the data collection. This leads me to believe I am hearing the raw output of the accel, out to the physical frequency limit of the accel. So I am hearing the high frequency noise that the meter will miss unless I have a very high Fmax set.

Are you guys getting these adapters from CSi or an aftermarket supplier?

I would never trust my hearing over my analyzer to detect bearing faults or determining the time of failure; never! The analyzer always works much better than ear or feel - always. I have confidence in technology and method I use - it works like a champ.

I am convinced that if you lock 5 vibration analysts in a room, eventually they will come out with 7 different opinions! There are many different ways to look at data; for everyone that swears by a particular method, there's somebody that swears at it. The best method is what works for you in a particular situation. Having some "backups" just in case your tried-and-true method fails is a good idea.

After 30 years in this business, I tend to avoid saying "always" and "never"....seems like those words always get me in trouble

Jon
Spintelligent Labs

I'm with you Jon... I am constantly learning new things. Of course you shouldn't trust only you ear to tell you there is a bearing problem. But if you set an 1800 rpm machine with an Fmax of 50 orders (as one well-regarded trainer suggests), then you are going to miss a lot of the higher frequency "noise" that shows up at 1800 - 3000 Hz. I use a 'special' time waveform setup that goes to 3000 Hz, taken as acceleration. This usually catches the bearing noise that I sometimes don't see in the spectra. And no, it's not practical to collect every point with a 5000 Hz Fmax with 6400 lines.

Data collection is always a trade-off... we are trying to collect "good enough" data in a reasonable amount of time. So, ideally, we use every tool at our disposal: moderately high resolution velociy spectrum, high Fmax acceleration time waveform, Peakvue, audible monitoring, "hands-on" at every point, accurate speed input, and a "yellow-handled" analyzer when necessary. As I've said before, I'd lick the machines as well if I thought I could 'taste' vibration....

I have been collecting data in plants and come across a 'bad' machine - example: had pulled my van into a refinery reeled out transducers to a machine - went back and the analyzer showing a bad bearing. Couldn't believe it! Went back felt great, sounded good - got others nearby and asked them to feel and everyone though it good. It really felt smooth. I checked everything, transducers, cables, you name it and after collecting a full set of data went to the maint mgr and told him the machine would fail within three days. He said, we'll shut it down now and go into it. Upon shutdown I felt the shaft and rolled it straining etc to feel something bad - nada!! We went in and the machine was terrible and coming apart. That's one of two such I've encountered over 39 years as such - 2007 will make 40 years for me. That was in 1984 and I've never doubted the analyzer since. It always rules over my 'feel'.

Sam,

My experience with turning a rotor by hand is the same as yours - a terrible bearing can feel just fine. On the other hand, a bearing that feels like crap isn't going to look good on the analyzer. If a bearing sounds bad, (assuming someone isn't mistaking cavitation for bearing noise), it's going to be bad, or at least it's going to need greasing!

Jon
Spintelligent Labs

We are also just adding headphones to our program. We have a couple bad bearings (one with outer race and one that was torn apart and the cage was about gone...hopefully it runs another 3 days til shutdown). Listening to the bearing with the cage gone...the rollers hitting together..using CSI 649 adaptor and filter..bypassing the filters..sounds like an airplane engine with the blades whipping the air..closest thing I can compare it with..but being a pilot..thats the first thing that popped into my mind when i heard it.

At least once I have found a fan bearing that had acceptable levels from at least 3-4 bearing methods from a couple of different instruments and still the sound from it was the sound of disaster. It was in a powerplant near the sea and the bearing was found to be full of condensated water, bearing was real bad, so water is a lubricant but not a good one in long term. So use all the tools you have when required. Olov

Sam, had you actually listened to the vibration signal from your analyzer, it would have sounded like the data looked... noisy. All we are doing with the headphone adapter is listening to the raw vibration signal from the accelerometer.... NOT the audible noise. A simple way to do this is to use and ICP power supply and hook the output to the input of any kind of recorder, digital, cassette, reel-reel, DAT. You don't even have to have a headphone adpater.

Thanks for the replies!

Rusty,
I assume you are plugging into the same jack that the headphones plug into. Are you using a standard cable or something you had to make??

Thanks,

Back in the dark ages of analog analyzers ( when I still had hair on top of my head), we commonly used headphones and also oscilloscopes - eyes can process input even better than ears, why not use either or both if possible. All the data acquistion software that I write includes oscilloscope mode input monitoring; I feel "naked" doing analysis without it.

Yes, I'm in the automatic diagnostic software business, but...

Mike, the Zen Nano actually has a "line in" jack for recording from any audio source. The idea is to use a CD player to "play" your CD's directly into the Zen which converts the input to MP3 format at a bit rate you select.

I already had headphones so I just bought a cable from CSI that has a stero jack on the end. I bought a cable from Radio Shack that fits the Zen input jack and added a plug that plugs into the CSI cable.

I forget some of the specifics now, but you can play the waveform of previously collected data. I think it was in 'stored data management' you could dump the data values of a selected waveform into a file. EPete introduced me to CoolEdit 96 (an older, free version) that would convert an ASCII table of values into a wav file. It was relatively easy, just long ago and far away.

Here is the post that Patrick is referring to:
http://maintenanceforums.com/eve/forums/a/tpc/f/3751089...801011951#4801011951

Going to the original post question about converting from database into wav, I don't know about rbmware, but in Emonitor 3.0 you can rightclick on TWF and export to an excel file. Then convert to text and multiple tools available to convert it to a wave as I mentioned in the link.

If it were just a case of converting one or two files from excel/txt into wave, post them here and I'll be glad to do it for you. But I suspect you'll want to be able to do it yourself.