Sign up Calendar Latest Topics Donate
 
 
 


Reply
  Author   Comment  
Curran919

Avatar / Picture

Sr. Member / Supporter
Registered:
Posts: 599
Reply with quote  #1 
Sales engineer asked me for some help on a tender for some big ol' VS pumps. The vibe criteria fall into the range of HI 9.6.4, ISO 10816-7 or API 610. We can use any of them and it won't be a problem, because for all of them, vibe is measured at the top of the motor stool (below motor). Now the client claims that we must also meet ISO-10816-3 criteria for the motor. Not only are these limits LOWER, but also measured at the top of the driver where vibe will obviously be much higher.

Seriously, is this guy right off or have any of you seen this before?
John from PA

Sr. Member
Registered:
Posts: 963
Reply with quote  #2 
It is generally stated that the ISO vibration limits for pumps apply to close-coupled pumps and motors (since the motor is integral to the pump) but not to separate motors. Therefore, a motor that is coupled to a pump may well have different vibration limits than the pump.

If you have the HI spec, you might check Appendix C Guideline for motor vibration for vertical pumps (informative) and see what if anything is said.
Shoveldr

Member / Supporter
Registered:
Posts: 89
Reply with quote  #3 
The first three standards you mention all are pump specific, so if they want to look at the whole system then ISO-10816-3 would be the one to use.  

The issue with these standards is that the customer is the one who defines if they are applicable or not, but they need to do it before hand.  If they are saying that it needs to meet this requirement on a purchase order or an RFQ then I would say you are stuck with it if you don't take exception to it.  If they are coming in after the fact you may be able to fall back on the other standards.  

How big are the pumps?  If I remember right those values were pretty loose.
Curran919

Avatar / Picture

Sr. Member / Supporter
Registered:
Posts: 599
Reply with quote  #4 
Unless someone can give me a picture of a VS pump run by diesel or belt, I'm gonna say that 95% of them are run by floating motor.

In ANY of this situations, ISO 10816-3 will ALWAYS be more strict than the three aforementioned standards to VS pumps. Then there is practically no use to have a VS standard. 10816-3 is a super general standard and doesn't get more specific than flexible mounting.

Sure, in the small picture it makes sense, but in the big picture, it's useless.

In fact, all of 10816-3 is pretty much useless.

We have applied the higher HI or API limits to the top of the motors before, but never actually used 10816-3 in parallel.
Curran919

Avatar / Picture

Sr. Member / Supporter
Registered:
Posts: 599
Reply with quote  #5 
Okay, now that I have calmed down...

Quote:
Originally Posted by John from PA
If you have the HI spec, you might check Appendix C Guideline for motor vibration for vertical pumps (informative) and see what if anything is said.


I've got the HI 9.6.4 (2009) and I don't see anything about this in any of the appendices. Is this from 2016 or an older version?

Quote:
Originally Posted by Shoveldr
How big are the pumps?  If I remember right those values were pretty loose.


Rated for 1.2MW driver. We don't have a contract yet, but apparently the customer is being a stickler on this point. I think the sales guys are going to go through with it and just try to minimize damage when we don't make the 2.3 mm/s at the top of the motor. Its going to be 20-25 feet in above ground, I wouldn't be surprised if we exceeded that with the pumps shut down in a strong wind.
Dan Timberlake

Sr. Member
Registered:
Posts: 116
Reply with quote  #6 
Does VS = variable speed ?

As good as variable speed drives may be for efficiency, they seemingly go looking for resonant frequencies, which for most vertical pumps are almost certainly "in there".  1X or blade pass covers a HA-YUGE frequency range with variable speed.

Good luck.
Curran919

Avatar / Picture

Sr. Member / Supporter
Registered:
Posts: 599
Reply with quote  #7 
Quote:
Originally Posted by Dan Timberlake
Does VS = variable speed ?

As good as variable speed drives may be for efficiency, they seemingly go looking for resonant frequencies, which for most vertical pumps are almost certainly "in there".  1X or blade pass covers a HA-YUGE frequency range with variable speed.

Good luck.
Whoops! I see the confusion. I meant vertical suspended as opposed to between bearing (BB) or overhung (OH).
Shoveldr

Member / Supporter
Registered:
Posts: 89
Reply with quote  #8 

Quote:
Originally Posted by Curran919
Its going to be 20-25 feet in above ground, I wouldn't be surprised if we exceeded that with the pumps shut down in a strong wind.


I've been in the exact place you are, good engineering practice and "thumb rules" say it doesn't apply but trying to prove it to someone who doesn't understand vibration is going to be hard.  So many things we assume are covered in these standards aren't.

I would take exception to the requirement it meet 10816-3 on the upper motor bearing and reference the note at the bottom the tables A.1 - A.4 in ISO 10816-3:

"2. Different and/or higher values may be permissible for specific machines or special support and operating conditions."

Have someone in your engineering group write up some BS about the flexible structure and set the acceptance levels at xxx mm/sec, or create a more complex acceptance criteria with some frequency bands.  Have a PE or equivalent sign off on it.

If you can't blind them with brilliance, baffle them with Bullshit.

 

Curran919

Avatar / Picture

Sr. Member / Supporter
Registered:
Posts: 599
Reply with quote  #9 
I had a bit of a windfall on this project.

We recently did maintenance on our standards library and got the new edition of HI 9.6.4 (2016). Lo and behold, there is a new informational appendix describing EXACTLY this problem, which now explains very clearly that the pump limits do NOT apply to the top motor bearing, and that while most customers insist on sensors at the top bearing, these are for information (and trending) only. It does state that (as a guideline only) a 1.5x multiplier of the pump limits can be applied to the top motor bearing, so naturally, the customer will want to make it an acceptance criteria, but that extra 50% goes a long way.
Previous Topic | Next Topic
Print
Reply

Quick Navigation:

Easily create a Forum Website with Website Toolbox.