During a typical vibration data collection, how much time is needed (by the analyzer) to take a reading from a bearing housing of a small motor?

I'm not sure if this is clearly taught in the vibration courses (Category I) or if a person without first-hand experience in data collection can have a feeling of the required time.

Comments are welcome.

This page is from "Data Acquisition" Part 2 of Vibration Analysis Certification Exam Preparation Package. It contains more than 150 practice questions on Data Acquisition for Cat I. Amazon Link: https://www.amazon.com/gp/book...ref=dp_st_1644150093

Regards- Ali M. Al-ShurafaVibration Analysis Certification Exam Category I Data Acquisition Question 147

Regards- Ali M. Al-Shurafa


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Original Post

I think this question should be reworded.  You state "...how much time is needed (by the analyzer) to take a reading..." but that is not what is implied in the question since there is no "(by the analyzer)".... I could be easily stumped since amount of time could imply installing sensor, locating data point on the analyzer, etc.

Also, VI Cat II notes are provided to the students with most (all?) formulas required to take the exam. So if your intent is ensure the student understand total DAT, then you should provide "typical" values for # lines, frequency span and # averages.   


Jim P


@ Ali M. Al-Shurafa,


"During a typical vibration data collection, how much time is needed (by the analyzer) to take a reading from a bearing housing of a small motor?" Unquote:

This quote: "During a typical vibration data collection",,,,,  sort of tells me that the question is directed toward a basic route's  measurement point's setup in the database with sufficient Fmax and # of lines, as does your quote: "(by the analyzer)": unquote.

With the "listed" times from the question's possible answers, I would chose, "B": "0.1 to 5 seconds".and have to think or assume the measurement point's  setup is within a reasonable manner, with a decent Fmax and number of lines,

Just my opinion and I could be totally wrong.

Thanks and Have a Great Day,



I like your comments. In fact, there is a room for assumptions that may ruin the objective of the question. "by the analyzer" was added to fill this possible gap.


One of the objectives of this question is to test if the reader has a practical feeling of how much time an analyzer takes to collect a vibration signature from a bearing housing during a routine survey.

On the calculation side, based on my experiments (using the equations), most of the reasonable configurations will require DAT between 0.1-5 seconds. I used a variety of resolution lines, frequency spans, averaging and overlap.

In fact, this question drew lots of discussions (more than other questions) when I called for comments from vibration practitioners.

Do you this a fair question for Level 1 (Cat I)?

Regards- Ali M. Al-Shurafa


It is my understanding that most (all?) certified training programs follow ISO 18436.

I don't have access to this specification but if you intend to generate a new training program (which of course is commendable) then I would think you should follow those guidelines.

If the intent of your question is to ask the student about DAT (data acquisition time) BY THE ANALYZER    <---- this is key assumption, then I would look closely at the ISO guidelines to see if that is within the scope of Cat I or Cat II. 

Best of luck

Jim P


You bring a very important and interesting point which is rarely discussed in the public domain. It is the accurate match between what students are trained on and what the standard certification calls for.

With respect to the standard requirements, Body of Knowledge BoK is very brief (too brief in my opinion) to the extent that a training manual of 100 pages might be too much to cover all topics. Because of this reason and other reasons, training agencies, usually, add more meet to their manuals such as:

1. More basic background information 

2. Higher-level details that are part of higher certification levels

3. More (relatively) advanced details and applications that are not classified by the standard.

Well, is this what the students are interested in? I guess it depends. Some trainees are interested to get as much information from the class as possible. Some trainees are clearly focussed on passing the exam and not interested in anything else (during the training).

Particularly for Q 147 and if the data acquisition time is taught in Cat I, up to my limited knowledge yes it is taught. To what extent? It varies. Is it part of the minimum standard requirements (Body of Knowledge of ISO 18436-2)? I do not think so.

Why is Q 147 included in the practice Question Bank? Simply because there are training agencies that teach it in their Cat I manuals. Cat Prep I series does not replace or substitute the existing training materials, it complements them. It reinforces the understanding of what is taught by practicing questions.

However, I've to emphasize that I'm not (officially) affiliated/biased to any of the certification bodies and what I sied may not necessarily represent their viewpoints. I respect their contribution to the development of the professionals in our field and the advancements of the vibration field in the industry.

Regards- Ali M. Al-Shurafa


Has anyone seen what the Vibration Institute CAT I & II work books look like?

The material is very early technology and somewhat forgotten. My son is studying the cat II workbook


I'm not familiar with the "work books" you mentioned. But I've a general comment.

Vibration Institute (and others) are required to follow certain topics to comply with the accreditation and certification process. All of the topics in the standard are old. Old does not necessarily mean bad, invalid or irrelevant.

I've my own reservation on the BoK but I do not think it the problem of the Vibration Institute.

Regards- Ali M. Al-Shurafa

Well, is there a need to update the format of the training manuals of the Vibration Institute such as the quality of figures? I guess you have a valid point and it has been a concern, raised since a long time. I'm not sure about the current versions though.

In terms of contents, in my opinion, the correction needs to come from the ISO Technical Committee, should there be an update. Otherwise, the changes would not be reinforced/accepted. By the way, the ISO  Technical Committee and Working Group members are from various organizations and countries. 

There are members in this forum who might be in a better position than me to comment on your concern.

Going back to the main topic:

When I read that last week I thought that if it were to follow the previous questions they were interested in the time it took to average samples with the pizo-accelerometers?

Yes, the question targets the time an analyzer would take to collect data using an accelerometer.

Regards- Ali M. Al-Shurafa

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