ITM Blog Posts

The Blog Post category contains blog posts associated with ITM’s testing services, LabVIEW programming, Test & Measurement Hardware, Boiler Monitoring Systems, and iTestSystem applications.

Accelerometers for Rotating Machinery Vibration Measurements

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Choosing an accelerometer for rotating machinery vibration measurements can be a daunting task since there are so many options available. This blog outlines the characteristics you should consider when choosing a piezoelectric single axis accelerometer for general purpose vibration measurements and presents some accelerometers to consider.

Characteristics of a General Purpose Accelerometer

When measuring vibration on rotating equipment such as motors, pumps, and generators, the most common measurement location(s) are on the shaft bearing housing(s) at the shaft centerline. At this location, typical vibration levels perpendicular to the shaft are < 100 g and the frequency range of interest is < 5000 Hz.  A general purpose single axis piezoelectric accelerometer with either a 10 mV/g or 100 mV/g sensitivity fits this criteria.

Other characteristics to consider are size, mounting options, cable connections, grounding, and cost. Several mounting options are available. They include magnetic bases, adhesive bases and stud mounts. The mounting option you choose affects the frequency range of your accelerometer measurements. The table below shows typical frequency limits for accelerometer mounting methods.

Mount Type Typical Frequency Limit
Magnet 2,000 Hz
Adhesive 5,000 Hz
Stud 6,000 Hz

5 General Purpose Accelerometers

The table below shows some examples of stud mounted general purpose piezoelectric accelerometers. These accelerometers all have a female 10-32 coaxial / microdot connector.  It is important to note that this is not a complete list of accelerometers and there are many options available from each manufacturer. I would encourage you to go to the websites linked in the table and see what’s available.

 
Manufacturer PCB Dytran BRÜEL & KJÆR Endevco Kistler
Model # 353B03 3055D1 4533-B 256HX -10 8702B500-M1
Sensitivity 10 mV/g 10 mV/g 9.8 mV/g 10 mV/g 10 mV/g
Frequency Range (±5%) 1 to 7000 Hz (±5%) 1 to 5000 Hz (±10%) 0.2 – 12800 Hz (±10%) 1 to 10000 Hz (±5%) 1-10000 Hz
Temperature Range -65 to +250 °F -67 to +250 °F –67 to +257 °F -67˚F to +257˚F -67˚F to +257˚F
Height 0.88 in 0.64 in 0.54 in 0.55 in 0.67 in
Weight 0.38 oz 0.35 oz 0.3 oz 0.14 oz 0.32 oz
Housing Material Titanium Titanium Titanium Titanium Titanium
Electrical Connector 10-32 Coaxial (side) 10-32 Coaxial (side) 10–32 Coaxial (side) 10–32 Coaxial (top) 10–32 Coaxial (side)
Mounting Thread 10-32 Female 10-32 Female 10-32 Female 10-32 Female 10-32 Female

For more information about collecting vibration data, accelerometers, iTestSystem, or test equipment rental, contact Mark Yeager @ (844) 837-8797 x701.

How Do I Collect Vibration Data with iTestSystem and a cDAQ?

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Our test engineers collect vibration data on rotating machinery using four basic tools.  We use a Laptop computer with iTestSystem software to stream accelerometer and rotational/speed pulse sensor data from a National Instruments cDAQ equipped with vibration and voltage input modules.  The video above shows how to collect vibration data using iTestSystem and a cDAQ.

Vibration Test Equipment

Vibration measurements are usually derived by analyzing data collected from IEPE accelerometers mounted to the rotating machinery structures and components of interest with magnetic bases or epoxy and a rotational/speed pulse sensor.  Typical rotational/speed pulse sensors are magnetic pickups excited by gear teeth and keyways or optical sensors triggered by reflective tape adhered to the rotating machinery.

The most important part of the data collection process is choosing a sample rate.  If  you choose a sample rate that is too low, the data you have collected is useless.  According to the Nyquist Theorem data must be sampled at a rate that is at least 2X the highest frequency you wish to record.  2X the highest frequency is a minimum number.  Most test engineers like to sample from 2.5x to 10x higher than the highest frequency they wish to collect.

Typical general vibration measurements are sampled at 2kHz.  However, vibration data collected from accelerometers and gear teeth pulses which is used for phase and speed measurements, and bearing fault detection, and torsional vibration determination must be collected at much higher sample rates like 50kHz.

Related Links

For more information about collecting vibration data, iTestSystem, data logging or test equipment rental, contact Ryan Welker @ (844) 837-8797 x702.

Wireless Strain Measurements with iTestSystem, LabVIEW, and Arduino

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On a recent project, one of our engineers needed to measure structural strain at several locations on mobile lifting equipment while in operation. Since the strain measurements were distributed and mobile, a wireless internet of things (IOT) solution was required. This blog describes the steps and tools we used to integrate our solution into iTestSystem and LabVIEW™.

What we offer

Are you looking for expert assistance with strain gauging, a wireless IOT solution or free custom engineering software platform that enables you to organize, acquire, view, and analyze data?  

Get In Touch

One of the wireless devices that we evaluated to monitor strain was a SparkFun Thing Plus (ESP32 WROOM) with a Load Cell Amplifier (HX711). The SparkFun Thing Plus uses the Espressif ESP32 Wi-Fi and Bluetooth MCU. It accepts a variety of digital interfaces including high-speed SPI, UART, I2S, and I2C. The HX711 load cell amplifier accepts four-wire Wheatstone bridges and outputs 24-bit data at either 10 Hz or 80 Hz. The digital signal from the HX711 was connected to a GPIO pin and clock pin on the SparkFun Thing Plus.   We used a Lithium Ion 2Ah battery to power both devices.

Figure 1: Wireless Strain Prototype Connected to a 4-Wire Bending Bridge

After making the connections and installing the device in a 3D printed case for mobility testing, our development engineer programmed this device using the Arduino IDE. Our wireless strain prototype was programmed to auto connect to a Wi-Fi network and output device ID, tag names, and data values via UDP or Webservice. We chose UDP because we only needed the latest strain/load values. Bundling the device ID with the strain data would allow iTestSystem to collect data from multiple devices. To test the wireless strain prototype and develop the UDP interface for iTestSystem, we modified the Simple UDP LabVIEW example vi.

Figure 2: Arduino IDE with Example Program

Next, we integrated the wireless strain prototype into iTestSystem by adding a new communication class into the existing iTestSystem IOT Communication utility. This new class allowed the utility to read the specific UDP data type associated with our prototype and output data to a shared variable. Shared variables can be logged to disk and analyzed with iTestSystem alongside other machine data.

Figure 3: Simple UDP LabVIEW™ Code

For more information about this application, iTestSystem, or our strain gauging services, contact Mark Yeager via email at mark.yeager@iTestSystem.com or phone @ 1.844.837.8797 x701.

ITM Winter 2020 Yeti Cooler Giveaway

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Our engineering services department is sponsoring a Yeti Cooler Giveaway.  This giveaway runs from January 6th, 2020 to February 28th, 2020.  To register for this giveaway and view the official rules click the Register Now button below.

Contact Ryan Welker via email:ryan.welker@iTestSystem.com or phone: 1.844.TestSys x 702 for help with any structural testing, strain gauging, and industrial monitoring applications.

Register Now

Happy Holidays 2019 from ITM

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May your homes be filled with warmth and your hearts with joy.  ITM wishes you a happy holiday season and a new year full of prosperity and adventure!

iTestSystem Tip: Strain Gauge Rosette Analysis

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When troubleshooting structural failures or validating FEA models through testing, strain gauge rosettes are used to find the full state of strain at areas of concern around the structure.  iTestSystem’s Rosette Analysis tool is used to calculate the principal strain, principal strain angle, shear strain, principal stress, and other values from strain gauge rosette data. This video shows how to use the Rosette analysis tool.

For questions about using the Rosette Analysis tool or other iTestSystem analysis tools contact Chase Petzinger.

Download your free version of iTestSystem today.

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Another Successful Condition Monitoring System Installation

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Last week our team successfully and safely installed another Boiler Monitoring System (BMS).  This system, a Sootblower Fouling Detection (SFD) system, monitors structural and vibration sensors that quantify the boiler’s response to sootblower operations. The SFD system analyzes the boiler response data and outputs Key Performance Indicators (KPIs) such as fouling level, sootblower efficiency, and sootblower health to automated boiler cleaning systems.

This boiler uses over 50 sootblowers located at different elevations to clean soot build-up from boiler steam tubes.  Since the vibration measurement locations are relatively far apart, the SFD system requires a distributed monitoring system consisting of several junction  boxes that monitor and process data for groups of sensors.  One team of engineers mounted the vibration sensors to the sootblowers and confirmed communication back to a local junction box containing the National Instruments condition monitoring hardware.  The other team installed the junction box panels and terminated the sensor cables.

After all the sensor installations and terminations were completed, each sensor’s location and calibration were verified.  While the sensor verification was being completed, one engineer worked with the mill IT department and the controls engineer to establish remote connection to the system and confirm communication with the mill’s automated cleaning system.

After commissioning the system and returning to our home base, our engineers are now monitoring the system through a VPN connection and assisting boiler operators with optimizing their cleaning process.

For more information about our ryan.welker@iTestSystem.com or phone @ 1.844.837.8797 x702

industrial Monitoring Systems

FFFFFantastic ITM Team Building Weekend: Norris Lake, TN

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Floating Dock Norris Lake

Zach’s Ready to GO

RJ Shredding

RJ Wakeboarding

Ryan Catching Air

Todd Wakeboarding

Todd wih Blue Gill

Moonlight Fire

ITM held its an annual team building over the weekend of October 11th; fun, fish, food, fire, and firsts ensued.

I would like to thank ITM owner Tim Carlier and our host Ryan Welker for a fantastic weekend at Norris Lake, TN.  It was great to hang out and get to know our team outside of work.  Now let’s get to all those Fs.

Food, Fun & Firsts.  The weather was amazing on Friday (mid 70’s).  After everyone arrived and a lunch of grilled hamburgers, hotdogs, brats, and grilled sausages prepared by Ryan, we all went for a four (not three) hour boat tour of the lake.  On the tour, Ryan, Todd, RJ, and Zach all took turns wakeboarding.  It looked like some of the wipeouts hurt more than others.  Some of the boaders reported bruising and extreme soreness.  To alleviate their aching muscles, we pulled into a secluded cove and floated with life vests in the soothing 76 degree water.  While floating and storytelling, we learned a few things about each other, among them, that this was Zach’s first time boating and water skiing and that no one believes my stories.

More Food, Fishing & Fire. After returning to the dock and another Zach first, some of us tried our hand at fishing while Ryan again cooked for us.  Dinner was salad, grilled steak, baked beans and baked fresh blue gill.  After dinner, everyone (almost) headed down to the patio by the lake for drinks and relaxation around the fire ring.  I hear that it was a late night around the hot fire and that the team likes story telling.

More Fun, Fishing, Fire. Saturday, we woke to a brisk, breezy, and drizzly morning and Todd sleeping on the porch.  Ryan fixed us goetta, bacon, and eggs which were delicious.  While Ryan was cooking, I went trolling for fish in my fishing kayak equipped with a fish finder.  Apparently, fish like to stay as far away from my boat as possible.  The fish finder said they were at least fifty feet below my boat.  My excursion was abruptly cut short by a monsoon.  Luckily, I was only 50 ft from the dock, so I only had to empty one inch of water from my kayak.

As we waited for the fog to clear, some of the team decided to turn fishing into a competition.  Todd ended up winning the tournament because he caught a turtle and the rock that I caught didn’t count.  The teams fishing tally: 9 Blue Gills, 1 Channel Catfish, 1 Red Eared Slider (turtle), 1 pair of corroded $400 Ray Ban sunglasses, and a rock.

At three o’clock the dense fog that drifted in after the fishing tournament finally lifted and the remaining team went on a boat cruise to the big water of Norris Lake.  With the temperature in the upper 50’s this ride was a little different than the previous day.  It was the first time I wore flannel with my swim trunks.  RJ was the only one brave enough to wakeboard, because we convinced him that he would be warm while in the water.  From his face while he boarded and the goose bumps when he got back on the boat, I don’t think the warm water helped.

After the boat ride and another great dinner (slow cooked ribs) by chef Ryan, we all retired to the patio again for drinks, music, and more story telling.  The full moon, roaring fire, falling hickory nuts, and the iPhone 11 led to a picturesque evening.  RJ used all of the new features of the iPhone camera to make sure it was well documented.

I believe that our team building weekend was a huge success.  All of us got to work together in a completely different environment than usual and I believe that everyone can appreciate each others contribution to the team.

Notes: other weekend notes that didn’t start with F.

Tim’s pellet gun is loud and probably scared off a few fishermen.

Deerfield lives up to its name.  I saw at least 100 deer over the weekend.

Golfing in the fog at Deerfield is fun for everyone, except for the deer I almost killed with an errant low fairway wood shot that skidded under its legs.  Ryan said it jumped and looked confused.

Everyone wanted to get fruit and veggies on the way home after eating all that meat.

iTestSystem Tip: Sensor Auto-zero Utility Update

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Our iTestSystem customers who routinely acquire data with high channel counts and data from full-bridge transducers recently requested that we update the sensor auto-zero utility to improve test setup efficiency.   In the latest version of iTestSystem, we updated the sensor auto-zero utility to include all channels that use the From Custom Scale option.  This update enables users to quickly adjust selected channel offsets with only a few mouse clicks.

One of our test engineers recently used this feature to test and calibrate a new load cell design for measuring loads in a manufacturing process.  He was able to quickly calibrate and zero the strain gauges along with a calibrated load cell and a pressure transducer prior to testing and before each directional test. The offset values are included in the calibration data files for traceability.

Contact Information: For more information about this update or iTestSystem contact:

Chase Petzinger – Integrated Test & Measurement (ITM), LLC. Email: chase.petzinger@itestsystem.com or Phone: 1.844.TestSys

iTestSystem Download

Machine Failures Caused by Intermittent Damaging Events

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Over the years we have been tasked with identifying the root cause of machine structural failures. In many cases, we can determine the failure mode through strain and vibration testing, order analysis, modal analysis, and operating deflection shape analysis.  What tests can you run when the damaging conditions are intermittent and not easily identified?

In these cases, we like to install a cellular networked temporary data acquisition (DAQ) system that can autonomously log vibration and strain data along with machine status data. We have deployed two types of DAQ systems to collect data remotely.  An interactive system that includes an industrial PC running our iTestSystem software and National Instruments (NI) Compact DAQ hardware and a headless system that utilizes NI Compact RIO hardware.  Our test engineers prefer using the interactive solution for troubleshooting because they can view real-time signal waveforms and collected data files, and then adjust the test parameters accordingly without having to reprogram the hardware.

Rugged Measurement System

Figure 1: Headless networked data acquisition system

When potentially damaging events are identified in the vibration and strain data collected by these systems, it is important to know the machine’s operating status. Collecting the machine status information is just as important as collecting the structural data.  Many machines transmit these operating variables and operating stages over their network/bus.  Recently we have recorded process data from Allen Bradley Control Logix PLCs via Ethernet/IP, mining machine data from a Siemens controller via proprietary TCP/IP protocol, boiler condition data from a DCS via Modbus TCP,  machine pressures from PI historian via the UFL connector (TCP), and vehicle speeds and pressure via CAN.  Fortunately, we were able to use and adapt LabVIEW communication protocol tools to build applications and addons that allow this network tag data to be collected along with structural data.

LabVIEW Modbus to Shared Variable Code

Figure 2: Modbus to Shared Variable Tool

After the data collection phase, our engineers perform statistical analysis on the sensor and status channels in all data files and aggregate the results into a database for searchability. To identify the root cause probabilities, you can process the channel statistics data using your favorite correlation algorithm or application.  The image below shows an example data set containing related sensor data that was processed using a LabVIEW correlation test tool.

LabVIEW Correlation VI

Figure 3: Correlation Test Example vi

Contact Information: For more information about our remote data acquisition service, our LabVIEW development service, or iTestSystem contact:

Mark Yeager – Integrated Test & Measurement (ITM), LLC.  Email: mark.yeager@itestsystem.com or Phone: 1.844.TestSys

iTestSystem Download

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