Infrared Imaging and Spray Testing of Walls
Tip written by: Infraspection Institute
Infrared imaging can be useful for detecting leaks within building sidewalls; however, timing an inspection can be tricky. Controlled wetting of walls can be used to simulate storm conditions during an inspection.
Water spray racks are mechanical devices that permit controlled wetting of a building surface. Spray racks typically consist of lightweight tubing and engineered spray heads spaced at regular intervals. When connected to a water supply and placed in front of a building wall, a spray rack can be used to deliver a deluge of water to an area of interest. The amount of water delivered can be controlled by using different size spray heads and/or varying supplied water pressure.
Spray racks are commonly used for testing the water tightness of curtain walls. During an infrared inspection from the interior of a building, spray racks can provide continuous wetting of walls to aid in leak detection. Spray racks can also be used to uniformly saturate a wall when infrared inspections are to be performed at a later time to detect evidence of latent moisture.
Because spray rack operation requires special tools and presents unique challenges, it is often best done by a qualified professional. Thermographers performing imaging during or after spray testing should keep the following in mind:
- Spray testing can be time consuming due to set up and/or repositioning of spray equipment
- Spray testing can cause significant building leakage requiring an interruption of testing
- Spray testing can be messy; avoid getting your imager wet
- When imaging from the exterior of a building, allow sufficient time for surface to dry and a Delta T to develop
Thermal imaging during spray testing is one of several applications covered in the Infrared Inspections for Home & Building Inspectors training course. For more information call 609-239-4788 or visit us online at: www.infraspection.com
Role of IR Inspections for Electrical Distribution Systems
Infrared inspections can be a valuable tool for detecting problems within electrical distribution systems. Understanding when and where to utilize thermography is key to obtaining maximum benefit.
Infrared inspections can detect and document evidence of loose/deteriorated connections, overloaded circuits, imbalanced loads, harmonics, and defective equipment. In some cases, infrared inspections can detect evidence of problems that may be overlooked by traditional electrical testing. Infrared inspections should be used to supplement, but not replace, regular preventive maintenance.
When setting up an IR inspection program for an electrical distribution system, keep the following in mind:
- Inspections should be performed at least annually
- Inspections should be conducted with the electrical system under normal load
- Inspections require clear line-of-sight to inspected components
- When possible, IR inspections should be performed 4 to 6 weeks in advance of a PM shutdown to allow time to order any necessary parts
- Exceptions should be reinspected after repair to help ensure that repairs were effective
- All new/retrofitted equipment should be inspected within 24 hours of installation
- All findings should be documented in writing in accordance with the Standard for Infrared Inspection of Electrical Systems and Rotating Equipment
Lastly, infrared inspections should only be performed by certified infrared thermographers who possess appropriate safety training and are thoroughly familiar with the system(s) being inspected.
For more information on thermographer training and certification or to obtain a copy of the Standard for Infrared Inspection of Electrical Systems and Rotating Equipment, contact Infraspection Institute at 609-239-4788 or visit us online at www.infraspection.com.
Using an Isotherm Feature
The more things change, the more they remain the same. This timeless observation is especially true when referring to the isotherm feature found on today’s modern thermal imagers.
The isotherm feature found on modern thermal imagers is somewhat of a relic having been around for over 25 years. In simple terms, an isotherm feature allows a thermographer to visually highlight areas exhibiting a similar apparent temperature on the imager’s monitor screen.
Originally designed for the monochrome imagers of the 1970’s, an isotherm is a user-definable, high-contrast overlay generated by an imager’s on-board computer or within image processing software. Prior to the advent of imagers with multi-color displays, the isotherm feature was a necessity for defining areas exhibiting similar temperatures. For other imagers, it was a requisite part of measuring temperature.
With modern thermal imagers capable of providing multi-color imagery and direct temperature measurement, it would seem that the isotherm is a feature due for extinction. There are, however, several instances where an isotherm may still be useful. Among these are:
- The ability to define areas operating within a defined temperature range
- A preset temperature alarm that automatically appears when an object exceeds user-defined temperature limits
- A highlight color that defines hot/cold areas on monochrome images
One should be aware that accurate use of an isotherm is dependent upon proper use of the imager. When using an isotherm, one should practice proper measurement techniques giving particular consideration to viewing angle, spot measurement size and emissivity settings.
Infrared equipment selection and operation are two of the many topics covered in all Level I Infraspection Institute Certified Infrared Thermographer® training courses. Level I training is available at several locations each month and through our Distance Learning Program. For information on thermographer training including course locations and dates, visit us online at www.infraspection.com or call us at 609-239-4788.
Defining Ambient Temp
Tip written by: Infraspection Institute
Ambient temperature is a term which appears in nearly all thermographic reports. However, many thermographers define ambient differently. Some define it as room air temperature while others define it as the temperature inside of the component enclosure.
According to the IEEE, for electrical components ambient temperature is the environmental temperature immediately surrounding the subject component. For devices located within enclosures, this is the temperature within the enclosure while it is closed and operating. For components in free air, it is the temperature surrounding the component.
Infrared inspection of electrical distribution systems is one of the many topics covered in the Level I Infraspection Institute Certified Infrared Thermographer® training course. For information on thermographer training or to obtain a copy of the Standard for Infrared Inspection of Electrical Systems & Rotating Equipment, visit us online at: www.infraspection.com or call us at 609-239-4788.
Gauging When IR Inspection Window Opens/Closes
Tip written by: Infraspection Institute
Solar-driven infrared inspections of insulated structures and roofs must be performed when sufficient Delta T is present. Knowing how to gauge when this window of opportunity is present is critical to the accurate collection of data.
Infrared inspections of structures often utilize solar loading to create temperature differentials necessary for the inspection. Common applications include moisture inspections of roofs and walls, structural inspections of CMU walls, and gauging product levels in tanks and silos. Often, these types of infrared inspections are performed during evening hours following a sunny day while the structure is cooling.
The time frame during which solar-driven infrared inspections may be accurately performed is often referred to as the ‘scanning window’. The scanning window is said to be open when conditions permit the collection of accurate data. A number of interdependent factors will determine when the scanning window opens and closes. These include, but are not limited to: target construction, amount of solar loading, local weather conditions, and imager sensitivity.
To determine when the scanning window opens, a thermographer should initially isolate an area with a small delta T indicative of an exception. For moisture inspections, this might be an area that is confirmed to be minimally wet. Using this area as a benchmark, the thermographer can periodically re-check this area during the inspection to determine if a Delta T remains. In general, the disappearance of a Delta T in the benchmark area will indicate that the scanning window is closing.
Infrared inspections of building envelopes and roofs are two of the many topics covered in the Infraspection Institute Level I Certified Infrared Thermographer® training course. For more information on other course offerings, call 609-239-4788 or visit us online at Infraspection.com.
Using Floor Plans to Identify Locations
In a recent Tip of the Week, we suggested using architectural drawings to supplement, or as a substitute for, thermograms for large structures. Structural blueprints can also be used to reference locations when performing infrared inspections of large physical structures.
Within the blueprint set for any large structure are individual floor plans which usually indicate the location of structural columns. Floor plan drawings are customarily laid out with column rows indicated by letters on one axis and numbers on the other. Using a combination of letters and numbers (A1, B1, etc.) to designate columns enables one to universally reference locations within a structure.
Because columns are permanent, their designations will not change over time and will not be affected by changes in structure usage such as floor layout or office location. When utilizing column line drawings to document your infrared inspection, keep the following in mind:
- Prior to the infrared inspection, obtain drawings with sufficient detail
- Verify accuracy of drawings with the subject structure
- Obtain a separate plan for each subject floor
During the inspection, mark the location of exceptions directly on drawings along with thermogram numbers, where appropriate.
Whenever possible, obtain extra sets of drawings to be used as file copies or for field use. When utilized properly, floor plan drawings can serve as valuable reference tools enabling everyone to “speak the same language” when it comes to properly referencing locations.
Infrared inspections of building envelopes is one of the many topics covered in the Level I Infraspection Institute Certified Infrared Thermographer® training course. For information on thermographer training or to obtain a copy of the Standard for Infrared Inspection of Building Envelopes, visit us online at www.infraspection.com or call us at 609-239-4788.
IR Inspections of Cool Roofs
Tip written by: Infraspection Institute
Energy and environmental concerns have caused many facility owners to look to their roofing systems for ways to conserve energy. Modern roofing systems known as ‘cool roofs’ can provide savings; however, they can present challenges for thermographers who inspect them.
Over 90% of roofs in the United States are dark colored. On sunny days, temperatures of these roofs can reach 150º to 190º F causing decreased indoor comfort, increased cooling costs, and premature aging of roofing materials. Advances in roofing technology have led to the development of ‘cool roof’ systems that help to solve these challenges.
Cool roof materials have a high solar reflectance or albedo. Compared to conventional roof materials, cool roofs operate at lower temperatures since they absorb less energy from the Sun. Cool roofs also have a high thermal emittance enabling them to radiate well and shed heat quickly after sunset.
Cool roof membranes are usually made of single-ply rubber or plastic materials such as EPDM, PVC, and TPO. These materials are usually white in color and have a smooth surface. Cool roof coatings or paints are an alternative for existing low-slope roofs.
Although cool roof materials are rated to have a high emittance, thermographers should remember that this value is an average emittance value calculated in a laboratory under ideal conditions and at a perpendicular viewing angle. During an infrared inspection, smooth-surfaced roofs appear quite reflective to a thermal imager due to the low viewing angle that is usually associated with inspections performed on foot from the roof surface. This condition is most severe on cloudless nights when atmospheric humidity levels are low.
Due to the low emittance associated with smooth roof surfaces, thermographers can easily miss the small temperature differentials associated with latent moisture. In order to mitigate errors associated with low emittance, thermographers should choose a short wave (2 to 5.6 microns) thermal imager whenever inspecting a smooth-surfaced roof regardless of membrane color or material.
Infrared inspection of flat roofs and proper equipment selection are two of the many topics covered in the Infraspection Institute Level I Certified Infrared Thermographer® training course. For more information or to register for a course, visit Infraspection Institute or call us at 609-239-4788.