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Abstract
Nuclear, infrared, capacitance, microwave and impulse radar methods for nondestructively detecting moisture in roofs were evaluated. No system was reliable enough by itself or by cross- checking with another system to eliminate the need for a few core samples of membrane and insulation to verify findings. Airborne infrared surveys are a cost-effective way of reconnoitering numerous roofs at a major installation. However, follow-up on the roof surveys is necessary. Of the several grid techniques examined, nuclear surveys were the most reliable. Hand-held infrared surveys are the most accurate on the roof method studied. Although an infrared camera costs significantly more than a nuclear meter, infrared surveys can be conducted more rapidly. Where numerous roofs are to be surveyed, infrared surveys appear to be the most cost-effective. In-situ measurements have been made of the thermal resistance of wet and dry portions of roofs. A lab apparatus has been built to subject 12- by 12-inch specimens of roof insulation to combined thermal and moisture gradients. Thermal resistance and moisture content periodically are determined, and characteristic curves are being developed for various roof insulations.
Nuclear, infrared, capacitance, microwave and impulse radar methods for nondestructively detecting moisture in roofs were evaluated. No system was reliable enough by itself or by cross- checking with another system to eliminate the need for a few core samples of membrane and insulation to verify findings. Airborne infrared surveys are a cost-effective way of reconnoitering numerous roofs at a major installation. However, follow-up on the roof surveys is necessary. Of the several grid techniques examined, nuclear surveys were the most reliable. Hand-held infrared surveys are the most accurate on the roof method studied. Although an infrared camera costs significantly more than a nuclear meter, infrared surveys can be conducted more rapidly. Where numerous roofs are to be surveyed, infrared surveys appear to be the most cost-effective. In-situ measurements have been made of the thermal resistance of wet and dry portions of roofs. A lab apparatus has been built to subject 12- by 12-inch specimens of roof insulation to combined thermal and moisture gradients. Thermal resistance and moisture content periodically are determined, and characteristic curves are being developed for various roof insulations.
Date
12/1978
12/1978
Author(s)
Wayne Tobiasson; Charles Korhonen
Wayne Tobiasson; Charles Korhonen
Page(s)
6
6
Keyword(s)
aircraft; detector; images; inspection; instrumentation; surveys; maintenance; measurement; moisture; reliability; test methods
aircraft; detector; images; inspection; instrumentation; surveys; maintenance; measurement; moisture; reliability; test methods