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Image highlights possible problems

25 January 2013

The latest easy-to-use, handheld thermal imagers can be used for a range of tasks in the process industries.Here, Fluke outlines some of those applications In process manufacturing, uniformity is essential; temperatur

The latest easy-to-use, handheld thermal imagers can be used for a range of tasks in the process industries.Here, Fluke outlines some of those applications

In process manufacturing, uniformity is essential; temperature measurement and control is one of the single most significant variables for uniformity.

Temperature monitoring can detect overheating delivery system components, help solve irregularities in electrical power supplies, predict operational machinery failure, detect blockages in supply pipes, and identify product inconsistencies. The latest easy-to-use, handheld thermal imagers, designed at the right price for use as an every day tool for maintenance engineers, are ideal for these tasks. In general, a handheld thermal imager will be used to look for hotspots, cool spots and other anomalies.

Here are some suggestions about equipment to monitor and what might be detected: Motors (hot bearings and windings) Motor control centres and switchgear (imbalance, overloads) Steam systems (failed traps, obstructed piping) Cooling systems (fouled cooling towers, blocked heat exchangers) Furnaces and boilers (damaged refractory, leaking ports), Pumps (hot bearings, leaking seals) Process piping (ineffective insulation, reduced flow) Tanks and vessels (product or sludge levels, leaks) Valves (leakage, sticking) Conveyors (hot bearings and drives).

What to check? Power distribution systems: Consistent, high quality electrical power is essential for process manufacturing. Thermal imaging can identify bad electrical connections, imbalances, overloads, harmonics, and other impending electrical equipment failures and prevent both uneven or inadequate power supply as well as downtime.

Motors, fans, pumps, conveyors: Thermal inspections of the bearings, shafts, casings, belts, gearboxes and other components that emit heat before failure can prevent unexpected equipment breakdowns on moving equipment.

Heat processes: Paper, glass, steel and food product production all require the uniform application of heat. These processes often utilise thermocouples or infrared temperature sensors for thermal control.

Frequently, spot measurements are not adequate due to process variations. Line scanners provide continuous thermal profiling in these cases, while portable thermal cameras can troubleshoot problems and determine the optimum spot to install a thermocouple or infrared sensor.

Pipes: In processes, fluids need to be delivered to the right place at the right time and in the right amounts. If a pipe is obstructed it can cause a chain reaction that throws an entire process loop out of tune, creating oscillation.

This will cause motors to cycle on and off too frequently; this in turn causes more frequent current surges which stress the electrical system and add harmonics that lower system efficiency and ultimately lead to equipment failure. Thermography can often pinpoint an obstruction, allowing corrective action before the whole loop goes down.

Valves: Process control valves are also critical to delivering fluids to processes at the right time. A thermal imager can monitor for leakage, sticking or excess friction. Also, the excitation coil of a valve may overheat from working too hard, pointing to a problem such as current leakage or valve size mismatch.When thermography indicates a problem, technicians can follow up by calibrating the valve or the valve positioner.

What to look for? In specific processes, a thermal imager can be used to look at product uniformity. For example, with a paper process, the paper may be processed by running it through an oven to cure it. A handheld thermal imager can be used to examine the thermal uniformity of the product as it comes out of the oven. Thermal variations are often attributable to other process variables such as non-uniformity in moisture or cure.

Every time a piece of equipment is inspected, a thermal image of it should be saved on the computer so that its condition can be tracked. The baseline data will enable comparisons that will help to determine whether a hotspot (or cool spot) is unusual or increasing, and will help verify when repairs are successful.

Suitable handheld thermal imagers are now affordable. Learning how to use them and how to use analysis and reporting software should prove easy. Typical examples are Fluke Ti10, Ti25 and Ti32 thermal imagers. Their three-button menu is designed for intuitive operation and navigation with the push of a thumb. They feature IR Fusion that integrates infrared and visible light images in full screen or picturein- picture views for enhanced problem detection and analysis. This real-time capability improves primary target identification, enhances issue locating efficiency and boosts reporting clarity.

The Ti25 and Ti32 can record and save voice comments with every image taken, on a 2GB SD memory card. Included is SmartView software, a modular suite of tools for viewing, annotating, editing, reporting and analysing infrared images, helping to identify potential problems before they cause failure.