What Is an Infrared (IR) Inspection Window?
The safety officer at your company held three meetings in September to educate the staff on the revised 2018 Edition of NFPA 70E regulations that outlines the “work code: for how personnel should work on electrical equipment safely. In a recent article, we reviewed the “Hierarchy of Controls” put forth by the NFPA where Elimination was at the top of the Hierarchy and Substitution was the second tier. To comply with the regulations, your company is considering adopting Infrared Inspection Windows to eliminate hazardous conditions when electrical assets are inspected. You have heard about IR Inspection Windows; however, you would not be comfortable defining the term to your peers. So, you decide to research the term and self-educate for a complete understanding. What is an Infrared (IR) Inspection Window? Let’s find out!
An Infrared Inspection Window is a window that is used to separate environments of differing pressures or temperatures while allowing light energy at a specified electromagnetic wavelength to pass between the two environments. IR Windows are also called viewports or viewing panes and must meet the strength and environmental requirements for the type of equipment in which they are fitted. The Windows must also be compatible with the infrared equipment being used. The Windows can be various shapes and sizes (square, round, rectangular or custom). IR Windows are an inspection point that is designed to allow infrared radiation to transmit to the outside environment so that a data point can be recorded using a thermal camera.
Why are Infrared Inspection Windows Desirable?
Electrical inspections must be performed on equipment that is energized and under “full load” conditions. Thousands of electrical workers are injured or killed each year on the job while performing electrical surveillance or maintenance on energized electrical systems because they open the panel to collect the data and expose themselves to energized electrical components. Per the NFPA 70E Hierarchy of Controls, if the hazard of a “fully loaded” asset can’t be eliminated, is there something that can be “substituted” that would eliminate the hazard? The answer is yes, IR Inspection Windows.
IR Inspection Windows enable the following:
1. Collection of real-time, condition status data on critical electrical systems and components under full load using the window without opening panels.
2. Mitigates the risk of injury or death of electrical workers who perform these inspections because the window maintains an enclosed and guarded condition, so personnel can perform temperature readings, thermal imaging and visual inspection without exposure to energized compartments.
3. A comprehensive, safe and intelligent protocol be designed and used for performing essential energized inspections on electrical equipment
IR Windows are one example of an Electrical Maintenance Safety Device [EMSD] that allows safe access for a thermographer to inspect energized electrical equipment. A previous article discussed EMSDs and why they are important in today’s environment.
What is an Ideal Infrared Inspection Window?
The ideal IR Window should have high transmittance, low emittance and low reflectance. It should allow all the infrared radiation to pass through it with zero loss. While windows cannot achieve zero loss of infrared radiation, they are very close to this ideal goal.
Types of Infrared Windows
There are different types of IR Windows:
1. Viewing Panes – windows that have a lens secured in a housing. Because the lens forms a seal between the internal and external environments, the inspector is not directly exposed to energized components and minimizes or eliminates the need for high levels of Personal Protective Equipment (PPE).
2. Inspection Grills – a window that contains a grill or “mesh” in place of a solid optic and typically found in mechanical applications for machinery guards or where both infrared and ultrasound data can be captured from the same access point. When opened, a grill does not maintain an IP65/NEMA 4 enclosed seal to protect workers from the energized components; therefore, elevated PPE is required.
3. Inspection Ports – infrared ports are usually no more than 15mm in diameter and can contain specialty lenses or adapters. The ports can be open (like a grill) or sealed with a lens (like viewing panes). The inspector must understand whether the port is open or sealed to determine the level of PPE required.
4. Custom Solutions – certain assets previously determined to be “un-inspectable” due to high energy levels or because a metal obstruction prohibits viewing the bus joints or connections may require a custom design of IR Window. It is possible to design custom IR Windows in various shapes and sizes to accommodate these situations.
Inspection Windows Are Evolving
Technology has enabled Inspection Windows to evolve providing more benefits to end-users. A perfect example of this is an Infrared Inspection Window that now has an ultrasound port which expands the utility of that window to include ultrasound, visual and infrared inspection capabilities. Future articles on IR Windows will explain the types of lenses used, advantages of polymer vs. crystal windows, applications for IR Windows, emissivity and financial benefits using IR Windows.
Conclusion: “Infrared Window” is a generic term as there are several categories of IR Windows available. When installed on energized electrical equipment, IR Windows should maintain an “enclosed and guarded” condition for the cabinet enclosure providing a safe working environment and minimizing the need for high levels of PPE. Inspectors must always understand if they are working with open or sealed environments to determine the level of PPE required to protect themselves from hazards. Windows are evolving as newer technologies become available.