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Author Topic:   Clarification on ISO 10816-6 vibration standards
vasanth
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posted 09-10-2002 02:26 AM     Click Here to See the Profile for vasanth   Click Here to Email vasanth     Edit/Delete Message   Reply w/Quote
I recently got a copy of the vibration standard ISO 10816-Part 6 ( reciprocating machines with power ratings above 100 kw ) . On page 6 Table a.1 there is a table for vibration classification numbers and guide values for reciprocating machines . The third column of this table is for Machine vibration classification number. Unfortunately the standard doesn't define what these classification stands for? It just mentions that " for example Many industrial and marine diesel engines may be classified in either classification number 5,6 or 7 ". Which is really vague .
Does any one have any clarification on this ? Also from what I understand that these limits are only for the reciprocating machine and not for the connected machinery namely alternators or Propulsion systems etc..
Any opinions on this .
Thankx in advance .
Vasanth

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OLI
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posted 09-10-2002 10:04 AM     Click Here to See the Profile for OLI   Click Here to Email OLI     Edit/Delete Message   Reply w/Quote
I think, and may be wrong that the makers of the machines are supposed to supply that info. Also that this is for the reciprocating machine must be true. I had recently a discussion with a electrical motor manufacturer that for obvious reasons have problems to get the motors to survive when connected to this type machines. I guess the only way is to have bearings dimensioned to cope w. the forces that the reciprocating things generate. Babbits type bearings seem to surviving better than ball bearings.

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fvereb
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posted 09-10-2002 02:29 PM     Click Here to See the Profile for fvereb   Click Here to Email fvereb     Edit/Delete Message   Reply w/Quote
If memory serves me correctly, I believe the machine vibration classification number is a number designated by ISO to be compared against a severity level. For example, ISO 10816-1:1995 Annex B (Mechanical Vibration - Evaluation of Machine Vibration by Measurements on Non-Rotating Parts) defines the classification numbers one through four (as they apply to machinery size). I might be waaaay off here, but I'm guessing that you may not have the complete standard or are missing a part there-of.
Then again, maybe I've been standing too close to the microwave again. Who knows.
Good Luck!
Frank Vereb

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Manuel Martinez
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posted 09-10-2002 02:40 PM     Click Here to See the Profile for Manuel Martinez   Click Here to Email Manuel Martinez     Edit/Delete Message   Reply w/Quote
help, please!!! Maybe not oficially "carved in stone" numbers, but something . . .it is hard to determine the clasification if nobody seems to know. I'm the "expert" here (customer) and my vendor rep. (manufacturer) doesn't even have a phone number or name for tech support, how can we agreed in clasifying...what ? it's either vibrating or is not!!!. Our own Diesel guys, who has been in the diesel bussines for a while, "no eye deer" (no idea) about the right amount of vibes admisible for these "beasts". For our big boys, I got a copy of an old memo from the Owners Group....X,Y & Z in foundation and Generator: that's all I have. thanks, I'm desperate, not for me, but other people need (?)to see numbers "or something..." Manny

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OLI
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posted 09-11-2002 11:43 AM     Click Here to See the Profile for OLI   Click Here to Email OLI     Edit/Delete Message   Reply w/Quote
Diesels are shaky creatures.
The ISO guys write: "Acceptable severity values will be available if and when circumstances allow". So what is acceptable is an arrangement between buyer and seller...For electric diesel generators in the size around 1MW pretty hi values are not uncommon like 20mm/s at turbo(s) mounting. I think class 3 to 4 is a reasonable compromise depending on size and operation If you run it as a spare for a nuke 3 min per week, you will have problems anyway. I think I saw some real world figures on locomotive diesels here recently so search on diesels also. Hope you can find something.

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Jon Chandler
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posted 09-11-2002 12:38 PM     Click Here to See the Profile for Jon Chandler   Click Here to Email Jon Chandler     Edit/Delete Message   Reply w/Quote
I believe the common US Navy standard for diesels is 5 mils pk-pk, measured on the mounting feet. This may serve as a starting point.

Jon Chandler
Spintelligent Labs

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Arne.Lindholm
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posted 09-14-2002 11:45 PM     Click Here to See the Profile for Arne.Lindholm   Click Here to Email Arne.Lindholm     Edit/Delete Message   Reply w/Quote
Just want to tell you what we use: 4.5 mm/s rms is new and delivery status for all acceptable operating conditions. 11 is limit for still acceptable for long time operation, and limit red = do not exceed is 18.
The classes in the ISO /6 is for us a typical vendor submitted list that makes the /6 being of very little use, exactly as Manuel is pointing out. If a vendor wants to write a contract with higher levels than above, we always ask for proof that his machine is made of superior margins and some exotic material that can withstand much higher levels than all the other machines in the world. Machines are still made of steel/metals/lubricants following the laws of physics. Yang Benar Arne

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Ron Wilson
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posted 09-15-2002 05:48 PM     Click Here to See the Profile for Ron Wilson   Click Here to Email Ron Wilson     Edit/Delete Message   Reply w/Quote
Another standard to use is ISO 8528-9 for diesel driven alternator/generators. This gives limits depending engine speed and generator output i.e >720 rpm but less less than 1300rpm: Generator >1000kW
Limits - Engine 45mm/sec Generator 18/22 mm/sec
cheers

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vasanth
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posted 09-15-2002 11:59 PM     Click Here to See the Profile for vasanth   Click Here to Email vasanth     Edit/Delete Message   Reply w/Quote
Thanks to all.
Ron I had to refer to the same ISO standard, which you were referring in your reply. Considering the fact ISO got a new one for reciprocating machines I guessed it would have been better but it seems to land me into more confusion.
Generally I am aware that for diesel engines limits sometimes make no sense. Imagine 45 mm/sec is something not worth measuring I guess. I also find that very little is being talked about diesel engine vibration analysis use standard FFT analysis. I am aware of Reciptrap (from Dynalco) for engines, which are probably medium & big size but not much is written for smaller caterpillar engines. The Limits from Caterpillar I heard was more liberal than ISO standards.
Only Art Crawford in his book mentions some characteristics of vibration of different configurations.
Arnie if you are trying to use the standard on an existing machine with no previous data how do you decide?
Regards
Vasanth

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Ron Wilson
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posted 09-16-2002 08:36 AM     Click Here to See the Profile for Ron Wilson   Click Here to Email Ron Wilson     Edit/Delete Message   Reply w/Quote
Hi Vasanth
I have often measured more than 45mm/sec on turbo blowers at point recommended by manufacturer. It is on the sheet steel inlet filter housing, which is really only a big drum, always thought it was a dumb place to take a reading !!

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Arne.Lindholm
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posted 09-17-2002 11:52 AM     Click Here to See the Profile for Arne.Lindholm   Click Here to Email Arne.Lindholm     Edit/Delete Message   Reply w/Quote
Concerning new or old machines, the same levels apply. Concerning trend as judgement when a vibration is high: If my tyres have low pressure, I do not trend the development to decide if to pump back to normal pressure at next gas station. To trend a development of someting bad is not needed to motivate an action. If above 4.5 mm/s rms, I want to find why, then if too much, I want to act. The diesel standard that is refered above is an after market business support from the OEMS's. How many users with practical experiences of diesels did contribute to those fantasy levels 45 that was mentioned above?
Concerning turbos, it happens that they are running at resonance and show 50/60 mm/s, but that will cause a lot of maintenance. Recently a ferry Denmark-Sweden blew two turbos out in the engine room and it worked as a hand-grenade explosion. I was happy to not take measurements that moment. Yang Benar Arne

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VibraTek
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posted 09-27-2002 06:43 AM     Click Here to See the Profile for VibraTek   Click Here to Email VibraTek     Edit/Delete Message   Reply w/Quote
Somebody at ISO standards office needs to visit a diesel engine using plant and get to feel what 45 mm/sec rms really means. I just tested 3 diesel engines one of which had 28 mm/sec and that baby was popping of pipes and rod and you name it every day. In two months these 3 diesel engines stopped 127 (yes, one hundred twenty seven) times. Somebody needs to be tell me that that is within specs.

Well! Excuuuuse me, but I am not going give green light to anything above 13 mm/sec rms because I do not like oil spewing off like a geyser into the air and I do not like seeing diesel engines that tear out their foundations.

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