Abstract: A near infrared (NIR) probe is disposed in a holder which is mounted within the wall of an enclosed process vessel. The probe reads and determines the moisture content of a product undergoing processing or drying from the enclosed vessel. The probe holder is formed with conduits, and a gas, such as air or nitrogen, is transmitted in periodic high pressure pulses through the holder conduits and transversely across the probe detecting end face to clear the probe end face of moisture and particulate contaminants to provide accurate real time moisture content determinations. The NIR probe and holder are disposed in a fluid tight construction.

Abstract: A near infra red probe is received in a holder which is mounted within the wall of an enclosed process vessel for reading and determining the moisture content of a product undergoing processing or drying, wherein the holder is formed with conduits, and a gas, such as air or nitrogen, is transmitted in periodic high pressure pulses through the holder conduits and transversely across the detecting end face of the probe to clear the probe end face of moisture and particulate contaminants to provide accurate real time moisture content determinations.