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Standard 204-05 (R2012) | Balance Quality and Vibration Levels for Fans

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Section/Figure/Table #: Table 6.3 Seismic Vibration Velocity Limits for In
Vibration velocity limits shown in Table 6.3 (for operation in-Situ)are referred to as "peak velocity, filter-out".
In absence of any more information I interpret this as peak velocity read from unfiltered time wave-form. If so, is it maximum of positive and negative peak or peak to peak divided by 2?
Other interpretations used by some of our vendors are (a) peak velocity read from frequency spectrum or (b) RMS of unfiltered time wave form multiplied by a scaling factor to arrive at peak velocity.
In view of above please clarify intent of the standard. This is important because we specify this as our acceptance criteria for our numerous tunnel ventilation fans.
Thanks in advance.

Proposed Change:
A clear definition of the term "peak velocity, filter-out" shall be included in the standard so that it is not subject to different interpretations by different people.

Pratap Jadav
New york City Transit
Posted: November 3, 2016

Section/Figure/Table #: Table 6.3 Seismic Vibration Velocity Limits for In
This is continuation of my previous email dated Nov. 3, 2016.
Other Interpretations of "peak velocity, filter-out" used are (c) Peak velocity from time waveform that is filtered to a specified frequency band(e.g. 10 Hz to 1000 Hz), (d)1.414 times RMS that is either measured from time wave form or calculated from FFT frequency spectrum, both obtained from vibration measurement filtered to
specified frequency band etc..
Thanks in advance. Hoping for a quick response.

Proposed Change:
The standard shall also specify frequency band, if applicable, associated with the specified vibration levels and also minimum sampling rate if digitized signal is allowed to be used.because all these factors affect measured vibration readings.

Pratap Jadav
New york City Transit
Posted: December 20, 2016

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