Temperature measurement techniques for spray foam applications

Abstract

Experiments were conducted to investigate the accuracy of thermocouple configurations in measuring temperatures within spray foam insulation products during application. Measurements of this kind are important for assessing products from the standpoint of thermal performance and safety. The response times of heating and cooling in air were first analyzed for several thermocouple configurations. The second phase of the investigation consisted of instrumenting five 2″×6″ wood frame cavities sheathed with a 2′ by 2′ piece of oriented strand board.A method is presented for instrumenting specimens in a way that is minimally thermally invasive, which leads to temperature results that can be trusted as highly accurate. The thermocouple type recommended for this application is insulated Type K 36 gauge, joined via welding. Larger wire gauges result in significantly underestimated temperatures, by as much as 30°C. In combination with thermocouple types with higher thermal conductivity of wires, this underestimation can reach as much as 60°C. The potential inaccuracies are particularly pronounced due to the low thermal mass and low thermal conductivity of spray foam insulation.