Uncovering seven uncommon IR thermometer applications

Savvy maintenance professionals know that infrared, non-contact thermometers fit beautifully into motors, drive and electrical maintenance. Simply scan the equipment while it’s operational and look for components that are running hotter than they should be. Find problems before they burn up, and you save money and time.

01/01/2010


Savvy maintenance professionals know that infrared, non-contact thermometers fit beautifully into motors, drive and electrical maintenance. Simply scan the equipment while it’s operational and look for components that are running hotter than they should be. Find problems before they burn up, and you save money and time.

Here are the basic IR applications:

  1. Measure the absolute temperature at a spot. This type of measurement is useful for trending the temperature of an object or comparing a measurement to a specification.

  2. Compare the temperature differential of two spots. You might, for example, compare the same component on two different motors.

  3. Scan an object and detect changes within a continuous area on it. This allows you to find hot or cold spots on housings, panels and structures. For example, you can check the heat sink of air-cooled transformers for cool tubes that indicate a restricted flow or a lack of flow.

    1. Troubleshooting components

      Using one of those basic methods above, turn your thermometer onto some of these applications.

      1. An uninterruptible power supply) UPS) uses dc batteries with terminal connections that are susceptible to loosening and corrosion resulting in excessive heat. Look, too, for hot localized connections in UPS output filters. Since large 3-phase UPS systems have capacitors wired in series and arranged in banks, the simplest way of testing a filter’s integrity is to check its relative phase-current balance.

      2. Low-voltage back-up batteries also should be checked for sound connections. Poorly attached cell-strap connections in a battery string can overheat enough to burn the posts.

      3. Light ballasts and other lighting fixtures overheat due to aging electrical components. A non-contact IR thermometer can detect an overheated ballast, for example, before it starts to smoke. In one survey of electrical service and maintenance personnel, 100% of those using IR thermometers said that they prevented thousands of dollars of downtime and repair expenses as a result of finding hotspots in electrical systems.

      4. Steam systems are especially important . Regularly compare the inlet and outlet temperature on steam traps. A properly operating steam trap produces a significant temperature drop.

      If the temperature doesn’t drop, the trap has failed open and is passing superheated steam into the condensate line. If the temperature drop is very large, the trap may be stuck closed and is not ejecting heated condensate.

      Condensate in steam lines waste energy, since the condensate reduces the effective energy of the steam, and can cause operational problems in steam-driven processes where the unwanted liquid can hamper operations or even corrupt the finished product.

      A faulty steam trap can cost a plant $500 or more per year. In a typical year, 10% of industrial steam traps fail. So, if a plant has 1,000 traps, an IR thermometer can save that plant $500,000 or more each year.

      5. HVAC systems are candidates for significant energy savings. Monitor all HVAC components as well as the building’s envelope. A non-contact IR thermometer provides data for quick energy audits and room balancing.

      A 50:1 distance-to-spot ratio (or better) makes elevated vents and returns very accessible. Know, too, the operating parameters of HVAC equipment. If a chiller should produce 44°F water, an IR thermometer can instantly reveal whether the chiller is operating within spec.

      6. Process monitoring makes a handheld IR thermometer a quality-control tool. You can use it to monitor processes to ensure that temperature-related process parameters are within specifications. In many instances, especially when only periodic temperature monitoring is required, a handheld IR thermometer is the natural choice for condition monitoring.

      Given the number of process industries (refineries, paper mills, pharmaceutical companies, bakeries, canneries, etc.), the possibilities for using a handheld thermometer are almost limitless. Likewise, the kinds of equipment that might be monitored are nearly limitless, too.

      In processes, fluids need to be delivered to the right place at the right time and in the right amounts. A handheld IR thermometer can pinpoint obstructed piping, malfunctioning automatic valves, cooler and heater malfunctions and a host of other potential problems.

      7. Monitoring of products themselves also allows a handheld IR thermometer to become a quality-assurance tool. Documented uses of handheld IR thermometers on products on production lines include rubber tires, aluminum auto wheels, urethane-molds and chocolate bars, among a host of others.

      Getting the most for your money

      Most IR thermometers operate pretty the same way, so it’s not necessarily obvious how one model could be vastly more accurate than another. Here’s what to look for.

      High optical resolution.

      The optical systems of all IR thermometers collect infrared energy from a circular area or “spot” created by an infrared beam. The farther from the target one gets, the larger the spot is. The resolution of an instrument is defined by the ratio of the distance from the instrument to the target compared to the size of the spot (“distance-to-spot” or “D:S” ratio) at its focus point.

      Some low-end instruments have a relatively low D:S ratio of 6:1 or 8:1. So, to measure a one-inch spot, the user must be six or eight inches from the target. More sophisticated yet affordable IR thermometers have distance-to-spot ratios of 30:1, 50:1 or higher. An instrument with a 50:1 D:S ratio can measure the same one-inch spot from a distance of approximately four feet. From four feet away, the entry-level instrument described earlier would be measuring a spot eight inches or more in diameter.

      In order to get a good reading the target must be larger than the spot size and ideally should be twice as large. For example, from the floor, you probably could not record the temperature of an overhead conveyor motor using an instrument with an 8:1 D:S ratio.

      However, it is likely that you could get the job done with an instrument with a 30:1 or 50:1 D:S ratio. High resolution is also important when working closer up because it allows precise measurement of smaller targets from a safe distance.

      Adjustable emissivity

      IR thermometers calculate the surface temperature of an object using the amount of energy emitted by the object and the efficiency with which the surface of the object emits that energy. The latter is its emissivity. Since the emissivity of most organic materials and painted or oxidized surfaces is 0.95, many IR thermometers use this factor in all temperature measurements.

      However, certain materials, such as concrete and shiny metals, are poorer emitters. So, using an emissivity setting of 0.95 in taking their surface temperatures of will not yield an accurate result. In order to use your IR thermometer in the widest variety of applications you’ll want an instrument with easily adjustable emissivity settings.

      If you need to measure overhead objects, make sure the optical resolution of your thermometer is high enough to give you an accurate reading from that distance.

      If you work in a process environment, consider whether there are points within the process where spot, non-contact temperature tests could be an effective quality control measure.

       


      <table ID = 'id3944720-0-table' CELLSPACING = '0' CELLPADDING = '2' WIDTH = '100%' BORDER = '0'><tbody ID = 'id3946428-0-tbody'><tr ID = 'id3946430-0-tr'><td ID = 'id3946432-0-td' CLASS = 'table' STYLE = 'background-color: #EEEEEE'> Author Information </td></tr><tr ID = 'id3946442-3-tr'><td ID = 'id3945197-3-td' CLASS = 'table'> Brian Stowell is Fluke’s marketing manager for infrared and electrical test equipment </td></tr></tbody></table>

      Troubleshooting motors, drives and electrical systems

      Following is an account of some of the most common uses for IR thermometry:

      • Motor monitoring. All electric motors have normal thermal patterns. Training and experience will make you familiar with such patterns and how they relate to a motor’s operation. Using an IR thermometer you can find the effects of conditions such as inadequate airflow, unbalanced voltage, failing bearings and insulation degradation in a motor’s rotor or stator. All result in overheating, as does a misaligned shaft coupling. To isolate drives that have problems, compare the surface temperatures of similar motors under similar loads and then flag deviant motors for further investigation.

      • Checking gearboxes. A gearbox will overheat and eventually fail if its oil level is too low or the internal lubricant fails to lubricate the gears adequately. An IR thermometer can pinpoint an overheating gearbox before failure and prompt the creation of a work order to correct the situation. It is a good idea to check the running temperatures of similar gearboxes under similar loading to pinpoint those running hotter.

      • Evaluating electrical distribution systems. Hotspots in electrical distribution systems may indicate a short circuit, a fused switch or an overload. Generally speaking, higher than nominal operating temperatures shorten the life of system components by damaging insulation and increasing the resistance of conductors.

        • Virtually all electrical connections degenerate over time due to the expansion and contraction caused by circuits being turned on and off. Check for heat buildup that indicates power loss created by loose, dirty or corroded connections. The fact that loosening of electrical connections will happen under any circumstances is a strong argument for regular inspections and defined inspection routes

          Also, troubleshoot transformers %%MDASSML%% hot spots in air-cooled units indicate winding flaws. Monitor switchgear and fuse connections, too, and be especially aware of high-voltage phase-to-phase power balance. Unbalanced phase-to-phase power can lead to the failure of induction motors, large computers and other critical equipment. Finally, transmission wires and cables can be monitored using an IR, non-contact thermometer to isolate cracks, corrosion and deterioration.

          Welding holds as a flexible manufacturing option

          By Dan Jones, Thermadyne

          Piping is critical to industrial operations across all spectrums, and welding is the process that protects the integrity of the pipes. Hospitals using medical gases, oil companies transporting their products, paper mills moving processing chemicals, even athletic facilities heating their fields in extreme temperatures, rely on the dependability of pipes and their welding. The welding process has been around for centuries, and continues to meet the intense challenges of gas, oil and other industries.

          One of the primary benefits of welding is its flexibility. Industrial plants can weld materials in one location, ship them to the facility for installation, and position them in various configurations. Flexibility is especially valuable in the repair process, as welders can crawl up in a pipe rack in a petrochemical plant, use a torch or some other cutting process to remove the bad section and make the repair. In the transportation of fuel and natural gas, repairs are time sensitive and are even made with products flowing.

          The strength of a good weld provides for vast options based on filler metal and process. It doesn’t matter the thickness or the size of the pipe, there is a welding process to join it together. With the proper engineering, you can achieve a certain hardness, flexibility or elasticity based on the environment.

          Engineers are not just using mild steel pipe anymore but are designing applications for higher strength alloys, heat resistant alloys and corrosion resistant alloys. Those alloy materials are expensive and difficult to machine, but there always seems to be a welding process and a filler metal developed to join them. This improved engineering helps pipes stay in service longer.

          New welding inspection technology provides several different measurements to evaluate, verify and validate the integrity of the weld in less time than in the past. Welding codes, standards and methods dictate what kind of weld requirements are needed based upon its planned use and length of service. Radiographic examination, ultrasonic examination, magnetic particle examination, or visual inspection may be employed. In the past, substantial downtime occurred while inspections were done.

          But now there is technology, such as automated ultrasonic testing, that runs around the pipe at fast travel speeds and measures the integrity of the weld immediately. Inspections can be made with the automated process going down the line, saving time and money.

          There is more control and more uniform shape on the inside of the pipe when you weld it than you would receive with mechanical joining, especially compared to fittings that would go at slants or turns. If you can control the shape of the weld beads on the inside of the pipe versus some kind of mechanical or a flange or a coupling, then those pipes are going to last longer than joined using a mechanical process.

          Engineers can also control how much product they want to flow through the pipe by controlling how much weld is penetrated on the inside of the pipe (the build-up). Some pipe line welders keep the weld beads flush on the inside of the pipe, so they are not losing any flow. If you have a weld bead going around every 40-ft. section of pipe that was 3/8 of an in. wide and 3/16 of an in. high, you are going to restrict the flow versus maintaining a minimum build up.

          The design of new welding equipment is, of course, also changing the landscape of the industry. Robotic and semi-automatic pipe welding systems are faster and more efficient thus saving time and money. Technology is also helping with a problem caused by the aging of the welder workforce. Accomplished welders are retiring and being replaced by those without their predecessors’ skill level. New equipment is being introduced that provides more control and consistency.

          Equipment like the Thermal Arc PowerMaster is centered on synergic control, otherwise know as “one knob control.” The wire feed speed is linked to the arc voltage, and when an operator makes adjustments, the two are matched through the machine’s software to deliver perfect, consistent welding parameters. Among its many applications, digital welding by oil companies in deep water and cross country pipeline applications. No matter how complex a situation a welding situation may be, engineers seem to rise to the occasion.

          Welding, a process that began thousands of years ago with primitive uses, has evolved into an essential aspect of all of our industrial operations. It will never be obsolete.


          <table ID = 'id3944933-30-table' CELLSPACING = '0' CELLPADDING = '2' WIDTH = '100%' BORDER = '0'><tbody ID = 'id3945198-30-tbody'><tr ID = 'id3945201-30-tr'><td ID = 'id3945203-30-td' CLASS = 'table' STYLE = 'background-color: #EEEEEE'> Author Information </td></tr><tr ID = 'id3945213-33-tr'><td ID = 'id3945215-33-td' CLASS = 'table'> Dan Jones is a Technical Sales Manager for Thermadyne, a global supplier of cutting and welding products. He may be contacted at Dan_Jones@thermadyne.com </td></tr></tbody></table>



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