The first thing to check is that the wiring is carried out and in accordance with the calibration sheet provided with the sensor. Check polarity of the voltage power supply.
The next thing to check is that the accelerometer is being powered correctly. Check the cable datasheet to see which two pins to be checking the voltage across. The voltage should be somewhere between 15 and 30 volts. Many systems would typically be 24volts. If the accelerometer has an integral cable then a point along the signal path needs to be checked. The closest point to the accelerometer should be sought to check the voltage. This ensures that a check for discontinuity in the wiring is taken with as much of the signal path being checked as possible.
If the accelerometer is seeing the correct voltage then the next check is to see if the accelerometer is generating a current that is at least 4 mA . To do this the multi-meter needs to be in series with the accelerometer. The circuit wiring needs to be disconnected at some point along the signal circuit and the meter inserted. If the machine on which the accelerometer is mounted is off you would expect 4mA. (No vibration condition). If the machine is running and vibration is being generated you would expect to see anywhere from 4 to 20 mA depending on the level of machine vibration. If you have 15-30V of power and you are seeing less than 4mA then the accelerometer is defective. If you are seeing greater than 20mA then the vibration levels are saturating the sensor or the sensor is defective.
If at least 4mA of signal is being generated then the accelerometer is most likely functioning correctly. If the accelerometer is showing more than 20mA and the machine is running then the machine vibration might be saturating the accelerometer and a lower sensitivity sensor is required. To check for this disconnect the sensor and repeatedly hit it with a light object. This should cause the mA current to increase. The Hansford Sensors 4-20mA sensors have a 5 second averaging circuit so ensure the light tapping of the sensor is repeated for at least 10 seconds to register above 4mA. If the accelerometer remains at 20mA or above despite being disconnected from the vibration then the accelerometer is likely defective.
Visualise, Measure, Troubleshoot and Correct machinery misalignment with Motion Amplification® and Easy Laser® Reliability Products from GVS.
Motion Amplification® and Easy-Laser® are fantastic complementary tools for visualising misalignment, measuring thermal growth, and correcting misalignment making Proactive (Precision) Reliability Maintenance even more achievable.
Because of my many years of experience in the field of installation and maintenance of rotating equipment I can say that installation is a fundamental thing. But why is this phase so important?
Well, because the installation has direct impact on the machinery, and it will determine operating conditions, performance, and life cycle cost. Basically, the way you install your rotating equipment is the way it will perform. And personally, I always ask myself why companies buy million-dollar pieces of equipment and let inexperienced installers do the installation. Then, they spend another million dollars in condition monitoring watching them fail.
Don’t get me wrong; condition monitoring is extremely important to understand what is happening to the machines and detect an early failure. But the fact is that most of the failures occur due to poor installation and design. Here, let’s focus on the installation phase of rotating machinery.
What do we expect from our machinery?
Reliable operation – We expect our rotating equipment to deliver its intended purpose or service without failure.
High performance – We expect our equipment to perform as per design.
Long service life – If our equipment has been designed for 20 or 30 years of operation, that is what we want to achieve.
Low maintenance cost – We expect not to spend any additional money after the investment has been made.
Responsibilities towards the installation
Communication, Procedures, and Integrity. These are responsibilities which are so important in the installation phase. Let me explain:
Communication It is a must to assure proper communication among the Design, Engineering, and Installation teams. We know there are constant challenges to keep the installation work to be on time and within specifications. The teams must have constant communication to be able to solve any difficulties or changes. In the real world not everything fits as it fits on the drawings. I think many of you have experienced this, right?
Procedures Installation procedures must be created according to design specifications and every member of the team must be familiar with them. Depending on which industry, the procedures will differ from each other. It is not the same thing to perform installation on the nuclear plant compared to pharmaceutical industry. There should always be a reference to which specific standard belong to the site where the installation is taking place. API Recommended Practices for Machinery Installation and Installation Design (API 686) are the perfect foundation to start with.
Integrity Integrity is an important part of the installation phase and it starts with Safety. Everyone who participates in the installation must go through safety training. Specific trainings must be performed such as working in heights, confined spaces, fire protection or chemicals handling. Breaking the safety rules will put the project behind the schedule therefore it is very important to follow them.
Always do things in the right order
The installation of rotating equipment must follow a certain order. The order of the installation procedure is designed to always start from the base. Foundations are the cornerstone of the entire installation. They are designed to hold rotating machinery and transfer and dissipate stresses and dynamic forces produced by pulsations and processes. Therefore, special attention must be paid to the foundations. They must be flat, coplanar, and levelled. If we skip the order of the installation procedures, we will not be able to complete further steps and not achieve reliable operation of our rotating equipment.
Finally, all the work must be properly documented during the process by creating digital reports to be able to review and compare the values and data. This is important for the references because further work will depend on the results.
Roman Megela Senior Reliability Engineer Easy-Laser AB
With so many different types, shapes and sizes to choose from, selecting the right vibration sensors (otherwise known as accelerometers) for your operations can be a challenging task. It is, however, essential. To ensure you specify correctly, there is a number of important factors you need to consider.
Vibration range and sensitivity – The range of vibration varies greatly from operation to operation. You should always specify vibration sensors to measure the maximum vibration range of your specific application. In a standard application (80g range), the sensitivity of a typical vibration sensor is 100mV/g, while in low vibration applications (16g) the sensitivity is 500mV/G.
Vibration frequency – Knowing the frequency span you need to measure is as important as knowing the vibration range. The frequency spans are dictated by the fault frequencies of the fastest-turning component in the machinery being monitored. The frequency span of a slow turning ball mill, for example, will be narrower than that of a high speed fan.
Environmental temperature – After poor and incorrect mounting, the greatest threat to the performance of vibration sensors is the environment. High temperatures can affect the operation of the electronics. However, charge-mode accelerometers are specially designed to work in applications with very high temperatures.
Contact with chemicals or debris – This can reduce the reliability of results and should therefore be considered carefully. To ensure performance and results are unaffected by exposure to chemicals or debris, accelerometers with corrosion and chemical resistant stainless steel bodies should be specified.
Hazardous atmospheres – Hazardous environments are those that contain flammable gasses or vapours, combustible dusts, or ignitable fibres, where even the tiniest spark could cause a fire or explosion. To protect people, machinery and productivity, you need intrinsically safe accelerometers, which are specifically designed for use in hazardous areas. They deliver the same level of performance as their non-intrinsically safe counterparts, but do so by using a lower level of energy.
Immersion in liquid – The average accelerometer isn’t constructed to be waterproof. If your application requires accelerometers to be exposed to liquid, the solution is to specify vibration sensors with integral polyurethane cables. This prevents liquid infiltrating the accelerometer and affecting the electronics – whether the sensor is at minimum sprayed with water or even completely submerged in liquid on a permanent basis.
Exit and profile – The exit and profile of a vibration sensor has minimal impact on performance, but if not considered can become a frustration for those responsible for maintenance. Depending on where the vibration sensor is located, you can choose between a top exit, side exit or low profile connection to allow maintenance engineers easy, safe access.
By taking these factors into consideration you can make the right choice in vibration sensor specification for the requirements of the average application or an industry specific use. If you need further assistance or require advice on special applications, GVS is here to help and can assist you in selecting the ideal vibration sensor. Get in touch today, or view our full range of vibration sensors, cables and accessories.
All rotating machinery is subjected to thermal exposure. The machines will react differently depending on temperature and material, either by expanding or shrinking. And that is a fact. Thermal growth is a serious thing when you think about it.
All rotating machinery is installed in trains. Trains mean there is a driver, the motor, and driven, which can be a pump, blower, compressor, or any other type of process machine. During the installation of rotating machinery, precision shaft alignment is performed. The shaft alignment will ensure that both shafts (driver and driven) are collinear. Collinear means that both rotational centerlines are positioned as if they were one.
The effect of heat on driver vs. driven
When the machines are started, the driver and driven heat up in very different ways. A compressor in a hot environment will quickly increase in temperature due to friction of its internal rotating parts, and compression of the media will generate and add more heat. Comparing to the driver, which can be an electrical motor, the situation is very different. The temperature will increase to a certain level and then remain the same — two machines with two different behaviors.
So, what happens when one of them increases its temperature relative to the other? It’s simple; the machine will start expanding. And when the machine expands, it will grow in all directions, move its rotational center out of collinearity and cause misalignment. But not only misalignment. Since there is a change in the machine geometry, pipe strain might also add more stress to the housing
Take thermal growth into account from the start
There are so many consequences of thermal growth in rotating equipment. Misalignment will, for example, also result in a bent shaft. Bent shaft will result in improper distribution of forces in the bearing, which will lead to failure of the lubrication. Therefore, we must be able to anticipate thermal growth by using available information from the OEM, or by performing the calculation by ourselves. So how do we do that?
The key is to identify how much growth to expect. This number must be used when performing the shaft alignment to “intentionally misalign” the machines prior to start. Let us use the compressor as an example again. If we assume that the compressor will operate at a higher temperature than the motor, when aligning, we must place the compressor below the rotational centerline of the motor. How much below will be determined by the expected thermal expansion growth of the material.
Final test run
When the machine is aligned with the thermal growth considered, it must run and operate until it reaches its full operating condition. Then it must be stopped, and the shaft alignment verified. This is our test run of the machine, to confirm a proper and reliable installation, and to achieve full operational life. We want to test before we go to full production to ensure our thermal expansion calculation was correct.
Think about aircraft maintenance. When there is an aircraft engine replacement, the pilots perform test flights until it can be confirmed that everything is operating as it should. And you don’t want to be on the plane knowing nobody performed the test run, do you?
Ultrasound is considered to be the most diverse condition monitoring technology on the market covering both air-borne & structure-borne applications.
The first signs of change in the operating condition of an asset are usually indicated in the ultrasound frequencies.
Ultrasound should be your first line of defence for asset reliability.
SDT’s NEW ‘Live Online Level One’ (LOLO) is a comprehensive course which walks you through the basics of Ultrasound and how this can be applied across the 8 application pillars. It exceeds ISO 18436-8 requirements and is a combination of 45+ years of technical and real-world experience. Sound daunting? Don’t worry.
SDT have broken this up into 16 x 2 hour virtual sessions over an 8 week period straight to your desktop, tablet or other mobile device. All available for On-Demand playback giving you the flexibility to learn at your own pace. Full course details can be seen here.
Don’t just take our word for it. John Garrison, recent LOLO graduate recently shared his experience and how he used the knowledge he gained to perform ultrasound inspection and analysis on equipment in his facility. Download the full testimonial/case study below.
It’s a common misconception that if a little grease is good then a lot means better. WRONG!
Too much grease will overheat a bearing causing separation of the oil from its thickener and will begin to run out of the bearing. This can set off a chain reaction resulting in lack of lubrication & hardening of the thickener which left unchecked will cause major issues.
Many studies have shown that only 33% of the open space within a bearing needs to be filled to achieve optimum friction reduction.
33%? How do you that?
ALS Global (Australia’s largest condition monitoring service provider) conducted an independent study over an 18 month period using the LUBExpert. The device was used across a large volume of grease lubricated bearings which were historically replenished using fixed calculated / time based rates.
Find out why ALS now choose the LUBExpert as their preferred method of lubrication. Download the full case study below.
How are you lubricating your bearings?
Save Time. Save Grease. Save Bearings. Use LUBExpert and ‘Grease Bearings Right’.
Mike is Technical Officer of Condition Monitoring at Rio Tinto’s Yarwun alumina refinery where he has held this position for over seven years. Mike has over 20 years working in the condition monitoring field, utilising popular technologies such as VA, Thermography and Oil Analysis. And now Ultrasound for the last 2 years!
Mike’s years of experience have given him a unique perspective on using ‘alternative’ condition monitoring tools such as the SDT 270 PRO, the world’s flagship ultrasound inspection device. With the SDT 270 delivering reliable, repeatable and calibrated ultrasound data and, with the power of signal analysis using SDT’s UAS software, Mike has been able to clearly demonstrate that ultrasound inspection should be the technology of choice for certain applications.
When using Ultrasound inspection technology in a harmonious relationship with other condition monitoring inspection devices, plant coverage increases, as does the overall reliability and availability of monitored assets. This then translates into greater production capacity and therefore overall profitability of an enterprise/company.
A portion of this case history was first published in The Industrial Eye: The official journal of the Australian Institute for Non-Destructive Testing – Condition Monitoring Issue – March/April 2017. It has since been edited and rectified to give further information regarding the case.
Read on for Mike’s ultrasound inspection success story…
Case History: Mike Halls – Rio Tinto Yarwun – 16-10-2017
Bearing Life Extension using SDT 270 Contact Ultrasound measurement
Equipment: P2620Vacuum Pump
Bearings: Tapered Roller Bearings
Pump Speed: 222 RPM
Motor: 630Kw – 6 Poles
Number of Vacuum Pumps on Site: 21
Costs associated with bearing failure
Overhaul cost due to a bearing failure: $120K Total Replacement cost: $300K Costs due to lost production or downtime: Currently there is some redundancy (as long as there are not too many other problems…). This may change in the near as further production demands are made on the plant.
Previous vacuum pump equipment failure modes and RCA’s have revealed that there has been an increase in bearing internal clearances & cage wear resulting in premature bearing failure. Due to the nature of these machines, vibration spectral analysis only revealed bearing defects in the later stages of the failure mode. Vibration analysis identified advanced propagation of fatigue due to surface cracks and spalling of the bearing raceway surfaces which were already resulting in unsatisfactory equipment performance.
Contributing factors to consider when using a vibration analysis approach are
a) a relatively low operating speed and
b) fluctuating ‘flow related’ vibration
Both of the above plant characteristics have the tendency to mask the early stage, low level amplitude bearing defect fault frequencies which, had they been detectable, would have indicated sub-surface bearing raceway defects and/or lubrication related anomalies. See the vibration analysis plots below as reference.
Vibration Analysis Plots
Below is the vibration Acceleration & PkVue spectral data taken the day after the acoustic vibration route was collected and, prior to any maintenance or lubricant/greasing intervention. Vibration analysis of the spectral plots indicates that the dominant frequencies relate to the vacuum pump pressure pulse fundamental & related harmonics. Neither of the plots indicates incipient bearing anomalies or lubrication related issues.
With traditional condition monitoring technologies being limited in their capacity for detection of the early stages of the bearing failure modes, trending of the degradation process was not possible. Without being able to detect and trend the early stages of the failure modes, this left the plant exposed when needing to determine a projected planned maintenance window. So, once the later stage defects were finally identified, the asset was already at a critical crossroad in
a) needing immediate attention or
b) risk plant failure with consequent potential safety hazards or production loses.
Solution: Acoustic Vibration Monitoring Trial
Acoustic Vibration Monitoring or contact Ultrasound, are terms used when an Ultrasound inspection instrument (in this case the SDT 270 PRO), utilises a sensor to contact (touch) a surface to detect attenuated ultrasound signals. Using a sophisticated instrument such as the SDT 270 PRO, the ultrasound signals can then be acquired as either dynamic (for analysis and playback) or static measurements (for trending) and logged in SDT’s proprietary database, Ultra Analysis Suite (UAS).
Just over twelve months ago, an Acoustic Vibration Monitoring strategy was implemented on a trial basis to complement the vibration analysis program on the vacuum pump routes. This was done mainly to assist with lubrication related concerns and incipient bearing defects that vibration analysis was unable to confidently detect. After employing the ultrasound inspection strategy (with the 270), and the data analysed in UAS, a number of lubrication concerns with the vacuum pump bearings were rapidly identified. See figure 1 and 2 below.
The above Acoustic Vibration Analysis examples indicate a significant upward trend due to elevated ultrasound generated by the bearings. The ultrasound signal and trend indicate metal to metal contact that is identified by an outer race bearing defect. The causes for this are either inadequate lubrication or incipient bearing defect.
As already mentioned above, at these locations vibration analysis showed only high frequency data with a raised noise floor. This could be attributed to the product ‘flow’ and hence masked the true vibration signal. On the contrary (and unlike vibration), the Ultrasound signal is not affected by the ‘flow’ caused by the pump and hence did not mask/conceal the bearing condition data. Due to the clarity of this anomaly, we can call this a ‘text book case’ because in this example, increased readings in ultrasound data related directly to an inadequate bearing lubrication condition.
Due to the findings via the use of the SDT 270 Ultrasound inspection device, the recommended corrective action was; ‘grease the non-drive end bearing and re-evaluate the ultrasound values’.
Upon the recommendations being carried out in a timely manner, further readings were taken with results shown in Figure 3 and 4 below:
Figure 3. Static trend after recommended intervention
Figure 4. Dynamic signal after recommended intervention
Note: the vertical y axis between fig 2 and 4 is different by approx. a factor of 4
The data collected with the SDT 270 post lubrication intervention shown in figure 3 &4 showed drastically reduced static and dynamic ultrasound signals. Hence, the follow up survey indicated that the values had significantly decreased to within the acceptable ultrasound range. Further inspections were then planned to monitor the health of the asset. Through the unique attributes only available through ultrasound inspection with the SDT 270, the plant was protected.
Thanks to Ultrasound inspection and the access to complimentary software, a conservative estimate is that the company avoided a $120K+ cost to overhaul the pump due to a bearing failure. A catastrophic failure ($300K +) and potential compromise to personnel safety and plant production, would have seen the cost to the company far in excess of this $120K estimate.
Ultrasound inspection has unique qualities which were instrumental in allowing condition monitoring to gain a true understanding of the health of the asset. For this application, other condition monitoring technologies were only useful once the asset was in the late stage of this particular failure mode exposing the company to high risks.
Furthermore, with the SDT 270’s ability to collect both dynamic and static data for trending and analysis, and the ability to record and analyse this data in the UAS software, the defect was easily identified and corrective actions taken.
Site Analysis and further actions:
Continued use of Ultrasound inspection technology to identify bearing condition will be employed so as to extend the reliability, availability and life expectancy of these important assets.
When using Ultrasound inspection technology in a harmonious relationship with other condition monitoring inspection devices, plant coverage increases as does the overall reliability and availability of monitored assets.
Thank you for reading. I hope this study proved to be of use to you confirming best practice in technology integration results in determining a higher accuracy in detecting equipment failure modes.
Lubrication is the life blood of a healthy operating rotating machine. This fact was discovered thousands of years agoand employed by the ancient Egyptians in pursuit of greater reliability for their own rotating machinery. E.g. Animal fats applied to wheels of a horse drawn chariot reduced heat and wear on parts!
While lubricants and machinery have evolved from animal fats and cart wheels, what has not changed in all the millennia since then is this: the lack of precise knowledge of quantity and frequency of lubricant application for greatest effectiveness.
Over time through trial and error, we can assume the lube techs and maintenance personnel of ancient Egypt determined the correct time to apply grease/lubricant.
‘That wheel shaft has not been greased for 2 weeks and we travelled through a sand storm yesterday. It’s time to get the animal fat out! But how much should I apply?’
Let’s face it, for a cart wheel, a ‘best guess’ lubrication strategy should probably work fine.
But today in the 21st century, with far more complex rotating machinery, maintenance and lubrication professionals across industry still face the same two critical questions:
‘How much lubricant and when?’
As civilizations have come and gone, greasing programs have still not evolved from the ‘best guess’ approach.
Did I Guess right?
As with our ancient Egyptian forebears, to answer the: ‘How much?’ and ‘When?’ questions, trial and error has led to the conclusions we have made about greasing. From trial and error (testing and research), mathematical formulae have been developed based on; bearing capacity, operational load, rotational speed and operating environment. However, experts agree that this formula is still only the ‘best guess’ regarding grease quantity and frequency of application.
And from this guess work, most industry lubrication programs are based on the calendar.
While calendar based lubrication programs assume that ‘someone’ ‘somewhere’ applied the mathematical formulae to determine the grease quantity and interval, what math can never account for is constant variations in:
Environment (dust, water, sand etc…)
These variables are critical in the determination of both grease quantity and interval between interventions.
So, we can confidently state: Even the most well thought out lubrication programs running on a calendar basis are ‘best guess’ and not ‘best practice’.
Given that poor lubrication practice (especially over greasing and under greasing), has a significant negative effect on the life cycle of bearings, the question needs to be asked:
Are you happy to leave the healthy operation of your critical assets to guesswork?
‘Know’ when to grease, not ‘Guess’ when to grease.
Do you want to ‘know’ when to grease or when not to grease? Do you want to ‘know’ the impact lubricants are having on your precious assets? If yes, then you will need to lubricate with the assistance of Ultrasound technology.
The key to understanding how ultrasound assists with lubrication is this: Friction causes Ultrasound.
With SDT hardware in the hands of a lubrication technician, a source of reliable information (knowledge) as to the friction condition of ANY bearing becomes available. With the knowledge an SDT instrument provides, calendar based programs evolve to become condition based programs.
With the help of Ultrasound, maintenance has the power to change lubrication culture from:
“Hey, it’s 3 months since the last lubrication intervention, therefore my best guess is, it must be time to put 20g of grease into the bearing.”
“Hey, it’s 3 months since the last lubrication intervention, therefore it must be time to use my SDT Ultrasound technology to help me determine how much grease to put in the bearing.”
‘I Guess all Ultrasound Lubrication instruments are created equal…?’
‘Best practice’ lubrication is only possible with high quality ultrasound inspection instrumentation.
SDT devices such as the LUBEChecker, LUBExpert or 270 provide dB µV data numerically on-screen. This data is reliable and calibrated based on a reference point (1µV = 0dB).
SDT instruments empower operators to confidently say, “when I attached the Ultrasound contact sensor, the screen read ‘X’dB. When I finished greasing the screen now reads ‘Y’dB.”
This is quantifiable data and can be included in reports as evidence given for reasonable action.
The point of the above is this:
Numerical data is criticalwhen asking lubrication technicians to grease bearings using technology.
Without credible data, what exactly would we be asking the lubrication techs to do with technology? They can listen but how do they report? ‘Grease the bearing until it gets quieter’. This methodology doesn’t work as ‘louder’ or ‘quieter’ is qualitative and is completely open to interpretation. You might as well just go back to the original guess work!
As already mentioned, with an SDT Ultrasound solution, current lubrication strategies can transform into ‘best practice’. By applying the use of the technology, an SDT customer claims the reduction of grease consumption by up to 95%! At the same time, by all measures at their disposal, reliability and plant availability is at an all-time high.
Evolve from ‘Guessing’ to KNOWING!
With the constant development of technology, the way industry lubricates bearings is evolving. Given that evolution simply means ‘change’, then it is time to change.
When it comes to lubrication practices we can now change from:
We can change from:
‘apply 20grams because it’s Tuesday’, to
‘it’s Tuesday so I’ll check my Ultrasound data to see if I need to apply 20 grams’.
GVS Reliability Products was privileged and excited to exhibit and co-sponsor IMVAC, the all new conference for Vibration Analysts & Condition Monitoring Professionals.
The event ran at the Gold Coast from September 5th through 7th. IMVAC (International Machine Vibration Analysis Conference) was designed specifically for vibration and condition monitoring professionals. This is a perfect fit for GVS as we strive to inform and arm the reliability professionals with asset health inspection hardware in our corner of the globe. From the amazing IRIS M, Motion Amplification technology, the ground breaking LUBExpert and our industrial vibration sensor range from Hansford Sensors, GVS added great value to the IMVAC community.
GVS supported the hosting of workshops, learning sessions and case studies to the latest technologies featured in the expo. IMVAC provided practical learning in the important aspects of industrial vibration analysis and the complementary condition monitoring technologies (Thermography, Wear Particle, Oil Analysis, Motor Testing, Ultrasound, Lubrication, Shaft Alignment and Field Testing).
IMVAC helped attendees form new relationships with fellow reliability improvement practitioners, and provided actionable new skills and knowledge that can be taken back to the plant to help attendees deliver even greater value.
One final word, our principal supplier Ultrasound hardware of SDT engaged the esteemed Tom Murphy to join the team at IMVAC to present and discuss the advantages of a sophisticated Ut inspection device and program. From all reports, Toms presentations were a success and many took take the time to talk to Tom while attending the event.
Top Reasons to Attend IMVAC
Focused Event IMVAC is dedicated to Vibration Analysis, Maintenance and Reliability, and Condition Monitoring Technologies
Variety of Content Each IMVAC event has 3 keynote presentations and over 50+ top-rated educational presentations from leading industry experts
Expand Your Network Network with other learning professionals from leading companies around the world including Shell, Dupont, GE, Siemens, Bridgestone, Weyerhaeuser, GM, Johnson Controls, and MillerCoors
Learn from Your Peers Improve diagnostic knowledge and skills while building relationships with peers who face the same challenges
New Technology IMVAC has an Exhibit Hall featuring more than 30 exhibitors providing the latest products and solutions
Add to Your Library The IMVAC Bookstore gives convenient access to the latest Condition Monitoring books (featured at IMVAC Australia and IMVAC USA)
GVS were indeed excited to be involved in the 1st IMVAC conference to be held in Australia.