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.