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What Are the Instruments Used in Condition Monitoring?

Feb 7, 2022

A reliable condition monitoring system can completely transform your industrial operation. You can optimize your maintenance schedule by focusing on the machines that actually need maintenance rather than following a routine that may result in redundant efforts. Even better, you can schedule maintenance for more convenient times. In addition, you can predict when machines are likely to need repair or replacement by gathering data over time. Monitoring your machines’ condition is essential to gain a competitive advantage.

While some modern machines have monitoring components built in, you don’t need to upgrade your factory floor. You can retrofit older machines with specialized instruments at a fraction of the price. An investment in condition monitoring technology yields significant returns due to the relatively low initial expense and massive potential for long-term savings. So, what do you need to make it possible? Let’s look at the most important instruments in a monitoring system.

Instruments used in Condition Monitoring - SAAB RDS

What Instruments Are Used in Condition Monitoring Systems?

How to Monitor Machine Condition

A monitoring system’s purpose is to observe a machine and determine if it is working optimally. If its condition has deteriorated, it must be able to detect this and take action. So, to monitor conditions, we must monitor signs of deviation from the norm. In the same way your physician monitors your condition by checking for things that aren’t in line with what is normal for your age and sex, machine monitoring looks for symptoms of problems that fall outside the expected parameters of operation.

The most telling sign of an imminent failure is excessive vibration. Most monitoring systems measure vibration. While this method is sufficient for most industrial equipment, there are other variables that can be used. Temperature readings can indicate overheating. Sound detection can listen for grinding or shearing which would indicate a need for lubrication. Even stationary equipment can be monitored using machine vision systems. Regardless, every monitoring system relies on the same basic components. What are these essential instruments?

Essential Instruments for Condition Monitoring

Every monitoring system has three basic elements. First, there is an input device such as a sensor that detects changes and outputs its observations as raw data. A data collection system retrieves data from a sensor, or multiple sensors, and organizes the data for further analysis. The final essential instrument is a powerful processing unit running analytics software that can output useful insights based on the patterns it identifies in the data.  

Overall, the system is analogous to the human body. We are wired with nerve endings that can detect pressure, temperature, and a host of other inputs. The nervous system routes this data to your brain, which then analyzes it and makes decisions based on the inputs. Your monitoring system will work in much the same way. For reliable results, you need to have good data capture, so let’s start with sensors.


Sensors are the foundation upon which your monitoring system is built. There are a wide variety of sensors for all kinds of applications. You’ll need to choose sensors that allow you to measure the correct variables without interfering with the machine’s operation. Fortunately, sensors have shrunk considerably and can even transmit data wirelessly in some cases, making them easy to install.

You can install multiple kinds of sensors on a machine to measure more than one variable or to add redundancy if you are concerned about a sensor failing. More expensive sensors will have tighter tolerances, which may be necessary for measuring fine deviations. Others can be more resistant to environmental hazards, including extreme pressures or temperatures. Consider some of the kinds of sensors available on the market today.  

Vibration Detection

By far, the most common application for sensors is to measure vibration. Vibration is one of the most reliable indicators of imminent machine failure. As a result, there are several ways to monitor vibration. Piezoelectric sensors produce an output when pressure is applied. Gyroscopic sensors can detect acceleration in multiple directions. Laser-based sensors can measure the time it takes for light to be reflected, which will fluctuate when a machine vibrates.

The type of sensor you choose will depend on the type of motion the machine produces. A sensor that must be mounted directly to a moving part would be ideal for a machine that performs a repeated linear motion. Wired sensors would not be suitable for rotary motion, for obvious reasons. In these cases, laser-based sensors can allow for vibration monitoring on a rotating piece of equipment without wiring problems.  

Temperature Sensors

Temperature sensors are useful when operating in extreme conditions or for machines that operate under heavy loads for extended periods of time. Likewise, if your processes require a very specific operating temperature, monitoring this variable becomes essential. Some temperature sensors work on contact, while others can use infrared imaging or lasers to produce a reliable reading.

Be sure to find temperature sensors that can tolerate higher or lower temperatures than what you need to measure. As sensors approach the extremes of their maximum range, they can become less accurate. By giving yourself some overhead, you ensure reliable results and will avoid damaging the sensor.

Sonic Sensors (Microphones)

Sonic sensors detect sound frequencies and can be very useful for a variety of applications. They can detect vibration provided they are isolated from other machines’ vibrations or mechanical noises. They can also spot deteriorating lubrication, as components will produce grinding sounds as lubrication breaks down. For best results, an array of microphones can be placed around a machine. Their results will be compared to ensure a reliable output.

Machine Vision Systems

You can even give your monitoring system a set of eyes to visually inspect items or equipment and identify faults. Sensors can trigger cameras, which will produce a sequence of static images and output these images to a GPU or TPU for processing. Combined with software, you can detect machines that are out of position, products that have manufacturing defects, or damaged packages, just to name a few examples.

Vision systems are excellent choices for dangerous conditions or remote areas, where sending human crews in is not feasible or cost-effective. Renewable energy facilities, such as solar farms and wind farms, have started using drones to visually monitor their equipment due to the large areas and long distances involved. Offshore rigs can use marine drones to visually inspect subsea infrastructure. While these systems do require more processing power than others, they can be extremely useful.

Data Collection and Processing

All of the data from your sensors is meaningless without analysis. For analysis to be possible, data must be curated and organized. Your sensors must feed their data into a collection and transmission system. There are several solutions available, depending on the kind of application you have in mind and the physical limitations involved.

Data Collection and Transmission

Wired sensors can be connected to transponders mounted on or near a machine. These transponders can then beam their data wirelessly, or via additional cables, to a central processing unit that organizes data into tables and sends it to a server for processing. This is the typical method for a factory floor, where a web of wires would not be ideal, but distances between machines are small enough to allow for low-power data transmission using Bluetooth or specialized Wi-Fi protocols.

Long-range wireless transmission is also possible. With GSM modules, you can use an available cellular network to send sensor data over long distances. Mesh Wi-Fi networks can also be used in large facilities. The goal is to get your data to a server where it can be processed either by on-site processing units or cloud compute units.

Data Processing

You can analyze the data that comes from your sensors in-house or outsource this work to cloud computing providers. Cloud computing has become more affordable and can process your data quickly. This method is preferable to using your own hardware if you haven’t yet installed a condition monitoring system. By using the cloud, you don’t have to invest in expensive processing power that will otherwise not be used.

Data analytics software can detect patterns in the data to shed insights on your machines’ condition. You can also input your own parameters for each kind of machine and sensor so that, when an out-of-spec reading occurs, the system will alert your engineering team. You can even program this system to take action on its own!

Start Monitoring Your Machines

If you have yet to set up a system to monitor your machines’ condition, it’s time. Contact SAAB RDS to schedule a meeting and learn how we can help you outfit your operations with the best in monitoring technology.