Peak to peak veloctiy conversion, please help

[Shribe]

Hello. I have received conflicting answers about converting peak to peak particle velocity values from mm/sec to in/sec. I am referring to peak to peak particle velocity in terms of building vibration. The value I am trying to convert is 1.48 mm/sec peak to peak particle velocity. Is it a straight conversion from mm to inches? If so, the conversion would be 1.48 mm/sec = .058 in/sec. Is this correct? I would really appreciate any help in clearing up this issue. Great site by the way.
Thanks, Todd.

 

[electricpete]

In the rotating machinery vibration world (don't know if it applies to you), there are generally three ways to express vibration (for a sinusoid or an overall):

peak/peak, peak/0, rms.

The peak/peak value is a factor of 2 higher than peak to 0 and a factor of 2*sqrt(2) higher than the rms value.

These may be different than "true peak" or "true peak/peak" which are based on the waveform itself.

Generally mm/sec represents rms and inches/sec represents peak/0. In that case 1 ips = 25.4/sqrt(2)mm/sec.

I see you identified mm/sec in pk/pk which is an unusual terminology again for rotating equipment. You need to know what format is the inches per second wanted in. Or just tell them when you give them your number.


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[Shribe]

Thanks electricpete for your help. In my case I am referring heavy truck traffic creating ground vibrations which are being felt inside people's homes. I am trying to find out exactly how bothersome these vibrations are. Also, I would like to know if they could cause structural damage to the homes. I am trying to convert 1.48 mm/sec peak to peak particle velocity to in/sec. Thanks again for your help.

 

[electricpete]

1.48 mm/sec pk/pk
* 1inch/25.4 mm
= (1.48/25.4) inches/sec pk/pk
= (1.48/25.4/2) inches/sec pk/0
=0.029 inches/sec pk/0
Again this may not be true peak.

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[Shribe]

Thanks for your help electricpete. I really appreciate it!
I was mistaken. I was trying to convert 1.48 mm/s peak particle velocity (PPV) not peak to peak. Therefore it is just a straight conversion from metric to imperial. 1.48 mm/s (PPV)= 0.058 in/s(PPV). I beleive this is correct now.