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Asset Condition ManagementPosts About vibration/alignment/balance
Formula for converting FPM to RPM
Registered Member It's almost like I was waiting for someone to ask that. [ more ]
Registered Member Oh no...what have I done! <g> Patrick, I like the bearing geometry calculator and some of the FFT calculations too. Some vendors may not appreciate me providing an easy way to calculate just how long that 100,000 line FFT at 100 Hz is going to take! No promises on when....but I'll keep the good ideas in mind. Jon Spintelligent Labs [ more ]
Registered Member How major of a revision? I like the new look. Do you want to tackle bearing frequencies? At least from the geometric side (x diameter, y number of rolling elements, etc.)? Or CSI's bearing info is easily eported to a text file. How about resolution, LOR, Fmax, time to collect z number of revs. Or converting the AFBMA bearing numbers to SKF numbers? You know, in your spare time. [ more ]
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Asset Condition ManagementPosts About Motor Testing
What causes a motor to draw higher than normal amps
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Registered Member I agree with Ron, the amps should have decreased if you trimmed and impeller. Pumps operating in parallel MUST have the same sized impellers, the pump with the smallest impeller can not overcome the discharge pressure of the other pumps and thus cavitates. A pump can draw the same amps if the impeller is trimmed....due to the impeller was too big to begin with and trimming it brings it back onto the pump curve? Had a customer once with a 2300HP 300 rpm pump have flow issues due to sediment... [ more ]
Registered Member MikeC, It looks like the best evidence you could provide might be a diagram of the piping arrangement. Can't agree more with EPete. Turning down a pump impeller and NOT seeing a decrease in current draw really says the pump is not causing the current draw in the first place. It really doesn't make much sense. There should have been a drop. Ron [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Beating phenomenum at Conveyor Drive System with Hydraulic Coupling
Registered Member check for soft foot issue at motor though u had said precisely aligned coupling.u should check the soft foot both dynamic condition as well as static condition. [ more ]
Registered Member As using Voith coupling, it is easy to determine the suitable hydro coupling specs for the machine. You just need input speed & motor kW (Power) & refer to the table provided in their website. I also experiencing same experience as you, high vibration for conveyor drive system & spectrum shows peak at 1X RS. I am not concern about the beating in the spectrum. For my case, the problem is only unbalance issue cause from the hydro coupling itself (eccentric I guess). I am using... [ more ]
Registered Member You can see in this attached picture that there is actually beating in CV029 with 3000 T/H (50% of design load) Vibration spectra seems like amplitude modulation with 4000 T/H because two frequencies are getting far away from each other. Greetings [ more ]
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Reliability Engineering for MaintenancePosts about Reliability Engineering for Maintenance
The purpose of maintenance
Registered Member The puropse of this thread, to me it is simple, describe the purpose of maintenance. Describe it in such way that a non-maintenance person (an accountant, a marketting officer, stores assitant) understand what Maintenance is. Terms like RCM1, CBM, PM, reliability or weibull are maintenance lingo only used in the "upper clouds" of maintenance and should be avoided in the description. The lower echelons will be hairsplitting anyway, imagine the outsiders.. Just like for Operations, their most... [ more ]
Registered Member The following is not meant to be demeaning, but to point out some irony. ************************************** I wonder if the post care of Terrence for Heinz Bloch is meant for this thread. The post appears misplaced. If I were a contestant in the game show "Jeopardy" and I had just read the post from Heinz as a clue, and I had to think of the question that was being asked to generate this post I would respond "How do you rid an industrial site of the "Siloed" thinking that separates... [ more ]
Registered Member Heinz Bloch Response from the Purpose Of Maintenance Discussion posted by Terry O The various and sundry exchanges are all interesting; none of them can be disputed. But, as is so often demonstrated by the preponderance of articles in numerous trade journals, and by the work output of hundreds of "benchmarking consultants," these exchanges usually do little more than state the problem. Few, if any, are giving unequivocal solutions and the writers appear to be unaware that some organizations... [ more ]
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Reliability Engineering for MaintenancePosts about Reliability Engineering for Maintenance
High Amperage problem with centrifugal pump motors
Registered Member The ARVs (Automatic Recirculation valves) for four of the parallel running pumps were observed passing, causing high capacity flow across the pumps. Therefore leading to high amperage problem. We are presently investigating the reason for the cause of ARV problem. Thanks for all of you sharing your ideas. Looking forward for more suggestions... Good day.... Mohammad [ more ]
Registered Member Is the motor correctly connected in star/delta? [ more ]
Registered Member Makes sense, running two pumps in parallel will increase the back pressure since this is a function of the flow. Try throtling a valve (not gate or block) in the discharge, probably you have a control valve somewhere? [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Shaft Runout Tolerances
Registered Member Dear, I also have a case about the runout check on a long shaft of vertical multi-stage centrifugal pump ( 4m length and 40mm shaft diameter for the area of impeller fit). This pump never was put in service before. Recently due to other issue found on other sites, we disassembled this pump to do a comprehensive inspection , meanwhile, found the runout is out of tolerance ( max. TIR found at shaft end is 0.18mm, where is for 1st stage impeller fit. ) Although I know that for this kind of pump... [ more ]
Registered Member http://www.easa.com/sites/file...R100-2010_1010-1.pdf page 6 http://www.roll-kraft.com/site...nspection-guidelines http://www.flowserve.com/files...t_fis159_slm6200.pdf page 3 Here are a few resources that show same tolerances as what has been posted Dave [ more ]
Registered Member Is 0.5mm coupling hub run out is acceptable for soft coupling? As per my knowledge the hub run outs should be less than 0.05mm. What is allowable run out for pump coupling hubs? [ more ]
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Reliability Engineering for MaintenancePosts about Capital Projects
Bearing Conversion Charts - AFBMA to SKF
Registered Member Dear Ahmed, Thanks for your support. Could you please send your E mail address on alpeshp@essar.com [ more ]
Registered Member Hello All, SKF offer a conversion guide at http://www.skf.com and http://www.aptitudexchange.com If any of you need to convert bearing designations to SKF, I will gladly have them converted for you just e-mail me your lists for conversion. [ more ]
Registered Member A tool that would be handy for you is the Bearing Expert program which contains over 1 Million Bearings. Can cross reference by part number, dimensions, bearing type, manufacturer and AFBMA number. Also contains over 200,000 bearings fault frequencies. http://www.reliabilitydirect.com/vibrationmeterproducts/vibfrequency.htm [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
3X DOMINANT PEAK (ONLY 3X) IN BOTH MOTOR AND FAN BEARINGS
Registered Member You should study your fan laws! Check “Law 3” at https://eldridgeusa.com/blog/u...he-3-basic-fan-laws/ [ more ]
Registered Member It seems to be speed related, get those plots and come back. [ more ]
Registered Member @Registered Member no phase data taken. Neither check any bode plots [ more ]
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Asset Condition ManagementPosts About Motor Testing
Number of Rotor Bars and Stator Slots!!
Registered Member Hello Experts, Can someone point me to a resource from where i can know the Number of Rotor Bars and Stator slots ? Of course ABB does not wanna give it. TIA, VinMan [ more ]
Registered Member Hello, You have discussed using the vibration spectrum to identify the rotor bar number but could you use the current spectrum to do estimate the rotor bar number? Also, Aditya, please can you explain how once you know the number of rotor bars it is easy to estimate the number of stator slots? Thanks! [ more ]
Registered Member You're welcome. I should clarify, the last paragraph of my last post referred to rotor slots. THMotorMan's post applied to stator slots. [ more ]
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Asset Condition ManagementPosts About Motor Testing
Megger Test Fails to Detect Winding Failure
Registered Member (Posted on December 8, 2008 @ 11:13 PM) I said I would post the results of the capacitance measurement on the motor after the rewind is complete. So here are the numbers: 1) Measured with Fluke 87 multimeter: 12430 pF per phase 2) Measured with a megger @ 1000 Volts: 11900 pF per phase 3) Measured with a megger @ 5000 Volts: 12300 pF per phase It can be seen that the capacitance to ground is a true constant unlike the inductance of the winding that varies over several hundred percent. In the... [ more ]
Registered Member It is a fact that experimentation is rarely seen on this board. I think it is fair to say that the working paper posted by quoted author on October28, 2008 at 8:29 failed completely from theoretical point of view. There was not one single result correct. The second paper, posted on December 9, 2008 at 01:11 AM, contained both the theoretical part and the practical experiments. So let’s have a look, for a change, on the practical results. I would really recommend reading this paper, because... [ more ]
Registered Member Thanks TestTech, I'm glad that you appreciated my contribution. Looking at the thread, I can see why you used the term battlefield, although I didn't intend to contribute to that type of environment. My goal was to get to the bottom of the question and also try to make the conclusion obvious to others, although sometimes I get sidetracked and sometimes I make simple things sound more complicated then they really are. I'm glad you were able to sort through all that to find the right... [ more ]
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Asset Condition ManagementPosts About Asset Condition Management
TREVI TESTING for RELIEF VALVES
Registered Member Thread lifted 1) Pre test defines whether or not the PSV is in such a condition it works or not. This can help give you a good historical view of the valve. i.e Is it neccesary to remove the valve every year if the valves operates and by the eye seems to be fine ? 2) Online testing has a economical advantage. I do not prefer the Trevi test equipment. I prefer the ventil preventtest or metrus Teson designed EQ for this purposes. They are more accurate and the tests are automated. Our company... [ more ]
Registered Member I have 2 clarification questions: 1) Do we really need to do the pre-overhual test and for what purposes? 2) Under what circumstances or purposes do we need to do online testing for PSVs such as Trevi test? [ more ]
Registered Member Irshad, Without going into the acceptability or otherwise of on-line testing for non-steam applications, I hope you agree that on-line testing cannot manage some of the failures modes in any safety valve. We use the term 'coverage factor' to describe the proportion of failure modes to the total managed by a given test procedure. On-line testing can never have a coverage factor of 100%. With due respect to what EPRI or other learned bodies say, there is no reason to ban on-line testing of... [ more ]
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Asset Condition ManagementPosts About Lubrication and Oil Analysis
Shell Grease Compatibility
Registered Member PAULENGR-very well stated. I agree that the Mobil Polyrex product is the most universally used motor grease and is suitable for all but the most extreme applications. As for compatibility I agree that the newer formulations have better mixing properties and the old grease compatibility charts might not reflect current practice but in JAXN14's case I'm not sure if he is willing to take a chance. If it was me I would gradually switch to the Polyrex product when changing bearings and/or motors... [ more ]
Registered Member MOST motor bearings are greased with a high temperature non-EP polyurea grease with a base viscosity right around 95-100, NOT lithium based. So right off the top I'm suspicious that you're using the wrong grease system, not just an odd viscosity. The vast majority of motor manufacturers and motor rebuild shops as a consequence use Mobil Polyrex EM or Polyrex EM 3 and nothing else. Once in a while this gets them in trouble with the high pressure roller bearings where a high temperature... [ more ]
Registered Member Does that mean ISO VG220 is suitable for motor bearings? cause from what I know typically ISO VG100-150 is preferred. What are the consequences if higher viscosity base oil chosen? What do you mean by overkill? pricy? and can you please define "normal" application? [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Key length calculator?
Registered Member Wonder if I put a disclaimer in there before uploading that years ago... Gald it's getting some extra mileage. [ more ]
Registered Member Length x width x thickness x 128.8 will give you your key weight in grams. We use this formula to find the half key weight when balancing rotors. I would think it would work to find the amount of key needed to fill a keyway. [ more ]
Registered Member Here are the results for cutting the simple key, which is half the exposed keyway, the full key and the stepped key. [ more ]
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Asset Condition ManagementPosts About Lubrication and Oil Analysis
Greasing shielded bearings ????
Registered Member Lee, In answer to your question about sealed and shielded bearings. Sealed bearings typically have rubber seals on each side. These seals make rubbing contact with the inner race, there is no gap. Everyone agrees that these can't be relubricated. They are normally only specified for harsh environments because the rubbing contact of the seals actually shortens bearing life, so they will not last as long as a shielded or open bearing in a good environment. Shielded bearings have metal or hard... [ more ]
Registered Member David We have three deep well effluent pumps in which we replaced the upper plain bearing for a flanged SKF bearing. The bearing is 2RS however the housing has a grease nipple fitted to which we fit a 6mm tube with a nipple at the assembly top plate. The path of the grease is into the bearing and out through the rubber seals. I understand how greasing outside of 2RS bearings would not allow grease into the bearing. In our case the force of the grease slightly distorts the seal but we know... [ more ]
Registered Member Some info you may already be aware of: - AFBMA number is provided on the nameplate of motors. - AFBMA Suffix PP stands for double shielded (i.e. 65BC03 JPP3) and suffix EE stands for double-sealed (i.e. 65BC03 JEE3) - Manufacturer p/n's often identify seal or shield. For SKF it is ZZ for double-shielded and 2RS1 for double sealed. All of the shields I have seen are metal. Seals by their nature require a rubbing contact so they will usually be at least partially rubber. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Difference betwen a velometer and an accelerometer
Registered Member If you go to the nitty gritty lo signal you should look at HOW more output is produced. Piezo material produce noise, if you just make higher amplification and not higher raw signal you also amplify the noise. Moving coil velocity probes are better to amplify as the noise produced in the sensor is much smaller. To get 1V/mm/s is no problem with very good long term results. Olov [ more ]
Registered Member I was simply comparing the values of an acceleration or a velocity signal. I was attempting to point out that in the lower frequency ranges, for a given vibration, you have "more" velocity signal than acceleration. As many of us have studied in classes, acceleration tends to attenuate lower frequencies and accent higher frequencies, displacement is opposite, and velocity is more even across a wide band. This means that at lower frequencies, you are trying to measure a naturally smaller... [ more ]
Registered Member Michael, you mentionned signal to noise ratio in your latest comment. What would be an acceptable range for a monitoring system for the full scale we want to monitor. For example, if we need to check from 0 to 10mm/sec peak, is it OK to have a signal from 0 to 10mVolt? What is typical? Thank you. Charles Auger [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Velocity and acceleration in vibration analysis
Registered Member Dear Mr JAMESK, Wellcome to this forum.you have plenty of explanation for your question and how you take it all.? when you collect vibration data using any vibration data collector you will get many unwanted noise along with useful data what is required for fault analysis.The problem is that the identifying signal (useful data) is usually drowned out in other noise emanating from the machine. Hope you know about FFT spectrum analysis,where in rotating machine faults are identified for... [ more ]
Registered Member In general and theory, that is true. The practical question associated with your statement that practitioners need to answer is that "is this particular amplitude (vibration) destructive to this machine?" The primary factor in determining the severity of the vibration is amplitude. Different machines have different sensitivities to vibration. Some machines break faster than others, if all are exposed to the same vibration. Keep in mind that the same physical amount of vibration can be... [ more ]
Registered Member Bill's statement should be well taken but I'd like to add one thing and that is that the user should not forget that these devices at their very basic level measure movement of a structure (I'm excluding non-contacting probes at present). So if we have a gearbox with mesh frequency of 3 kHz and a rather high mesh component of 20 g's peak, the movement of the casing at that frequency is 0.043 mils p/p (0.001 mm p/p), a very small amount of movement. Using that same example, the velocity would... [ more ]
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Welcome to AMPBook and Article Discussions
Vibration Analysis Level 1 (or 2) Practice Question Q 45
Registered Member Jake, Thanks for the chart. I've comments that might be useful for some readers. There is a fundamental difference between the two waveforms (in Jake's post) which is physics. To explain this, let us use a third illustration. [source: https://www.researchgate.net/f...ia-18_fig1_262450664 ] Jake's upper plot is the amplitude (elevation of a point of the string) in the y-axis versus the location of points (examples are A, B, C, etc) along the length of the string on the x-axis. So here we look... [ more ]
Registered Member Dear colleagues here a Vibration poster that might be of your interest. ( no cost to download) https://reliabilityweb.com/steal-these-graphics [ more ]
Registered Member Hi, here’s a good visual of exactly how to find the period or frequency of any graph. [ more ]
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Reliability Engineering for MaintenancePosts about Reliability Engineering for Maintenance
Calculating Plant Availability
Registered Member From my days in power generation, maybe these basic availability statistics would be helpful. Over a given period for a generating unit: Availability Factor = ratio of time on line to total time in the period. Capacity Factor = ratio of actual output to output that a unit can achieve at rated capacity (sometimes called maximum dependable capacity). Available Capacity Factor = output that could have been achieved, if desired/required, to the output that a unit can achieve at rated capacity. [ more ]
Registered Member The difference between the two might be called equipment availability vs. system availability. Could it not depend at which level you are measuring? [ more ]
Registered Member Ecky, You say: Why so? The definition of availability is just that; that the item is ready for use if required or it is already in use. I don't see the need to redefine availability because of a problem that you believe exists. Such a move would not help you with your original problem either, since you still have to account for slowdowns as well as quality related issues. In my view it is better to get a clear picture if what each term means and use the right one for your purpose. There are... [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Inboard - Outboard ??
Registered Member Then on verticals: what do you use? Using numbers; Mtr top brg = 11 or 1H or ?...? On Horz I use: Mtr ODE Horz = AH On Vert I use: Mtr top in-line w/flow = A1 I've found this combination of a & n to work quite well allbeit not he only system that works and works well. In addition I post engineering files available for all that have photos of all equipment along with the machine sketches and point ID's as well as some of the reports containing such info and block sketches. But for the... [ more ]
Registered Member We ask 5 of our men which bearing they considered to be the inbd, and otbd, and all were confused. This was on an overhung fan, so this is why we adopted the number method. Much easier to understand. Rod [ more ]
Registered Member I think you just have to say inboard and outboard to what - I have always used the drive exchange. So a jackshaft bearing can be both inboard the the motor and outboard to the fan. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
High Gravitational Envelope (gE value) in motor bearing
Registered Member I agree with OLI listen to it with a stethoscope. No information on the motor drive train and i see the bearing is an NU type... maybe application related? [ more ]
Registered Member I don't mind making calls on brand new motors, on the contrary. Is it on VFD or VFD close by? It may be slight change in operation position that made a move in to a damaged operating zone or infinite other reasons. Do it sound like a disaster with stethoscope, screw driver or yellow handle analyzer? Call it then, maybe as planned as suitable. There are no worse than having a fail sitting on data indicating that is the case and not reporting, minimum issue a warning report to swap brg if stop... [ more ]
Registered Member You have a pretty raised peaking level on that time wave for some peaks almost 8 g? also that fft is still in Velocity if you press 'A' on the keyboard should show in acceleration. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
sleeve bearing scraping and blue-check / dry-roll check: common misconception
Registered Member I believe these date back to the 70's. The first analysis of the stiffness properties is more recent. I don't remember your application. Some have been used on exciters. [ more ]
Registered Member Sorry, I missed the "socket" part. We have nothing like that. I take it you have had good experience with those? We do have one application (main feedwater pumps) where we installed new-fangled "fluid pivot" bearings from Pioneer. Somehow uses oil on the back side of the pad to support it rather than mechanical contact. http://www.pioneer1.com/engine...id-pivot-10-reasons/ You may remember that we called you up after we installed them because our vib jumped up. I think your initial idea was... [ more ]
Registered Member That's a reason for the ball and socket design over the ball on plate point contact, design. [ more ]
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Reliability Engineering for MaintenancePosts about Capital Projects
How to set Magnetic Center of the motor
Registered Member It's not unheard of for 2-pole motors to oscillate axially when uncoupled. Two factors drive this behavior to be more common in 2-pole motors than slower motors: 1 - 2-pole motors tend to have weaker centering force than slower motors due to fewer vent ducts or no vent ducts. 2 - 2-pole motors tend to have stronger air-related forces due to axial fan design. You can often see this by temporarily blocking off air entrance on double-end ventilated motors and looking for change in rotor... [ more ]
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Asset Condition ManagementPosts About Lubrication and Oil Analysis
viscosity conversion at different temperatures
Registered Member Thank you for your response Pete. But like you said, the ASTM D341 equation only applies to petroleum products and propylene glycol does not fall under such category. I ended up using the Jouyban-Acree model to acquire the appropriate equation. Thank you Nurudin for a response as well. [ more ]
Registered Member For ASTM D 341 better using graph just plot two known point and we can predict the othre. for online software, we can use this link http://www.widman.biz/English/...ors/Operational.html [ more ]
Registered Member The spreadsheet is limited to petroleum products at temperatures where the are above 2cSt. More details: The general form of the relationship eqn used in the spreadsheet is log (log(Z)) = A - B log T (from ASTM D341) ASTM D341 gives various expressions for Z depending on what range you want the forumula to be accurate over. Specifically: Z = (v + 0.7) from 2E7 cSt down to 2.00 cSt Z = (v + 0.7 + C) from 2E7 cSt down to 1.65 cSt Z = (v + 0.7 + C − D) from 2E7 cSt down to 0.90 cSt Z = (v + 0.7... [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Bearing Cross Reference
Registered Member Go to SKF Bearing Handbook for Electric Motors , then go to the pages numbered 28 and 29 (as numbered in an Adobe viewer). Once you've identified the bearings, go to the pages immediately preceding the conversion page and you find help on the bearing frequencies. [ more ]
Registered Member I have two bearings that i need help crossing over to bearing number (if any one can help me out): 90BC02J3 100BT03M [ more ]
Registered Member Alec's bearing list above gave me an idea. For you CSI users, why not include this list in your 'note codes'... would make it much easier to note the bearing number when you find a suspect bearing. [ more ]
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Asset Condition ManagementPosts About Lubrication and Oil Analysis
The right grease for electric motors