With the launch of the DewTector, Coperion introduces an innovative moisture measuring device designed to provide reliable, automated online measurements of surface moisture content in bulk materials, particularly plastic pellets. 

The patent-pending device offers an economical, simple and reliable method to help plastic manufacturers and recyclers monitor moisture levels more efficiently. It addresses a critical challenge faced by processors in maintaining both product quality and maintaining compliance with industry standards.

The DewTector uses a straightforward approach ─ it introduces a partial flow of bulk solids into a pressure-tight product chamber. The system determines the moisture content by analyzing the moisture released into the airflow. As the air absorbs moisture, it is analyzed by a hygrometer that measures only water content. This targeted detection ensures reliable results unaffected by other substances or changes in material composition. 

The system neither requires extensive calibration, nor the use of chemicals for different materials or recipes, making it easy to operate and maintain. The system achieves an accuracy of +5% to −15% across moisture levels ranging from several thousand ppm to a few hundred ppm, with up to ten measurements per hour. 

DewTector in a typical bypass line configuration. Its compact design, with a height of only 184 mm (flange to flange), simplifies process integration. (Source: Coperion)

Challenges of Moisture Measurement in Plastics

Plastic manufacturers often face the challenge of moisture entering their final products, which can originate from various sources such as insufficient drying, defective water separators, leaking wash nozzles, or environmental factors like rain and condensation. 

If moisture levels go undetected, it can lead to costly product complaints and reputational damages. Additionally, processors must adhere to strict moisture content limits to ensure high-quality output, and the recycling sector requires dry input materials for effective processing.

Traditionally, moisture measurement has been labor-intensive and prone to inaccuracies, often relying on sporadic manual assessments of relative humidity in bags and containers. Existing automated methods, such as capacitive and microwave resonance techniques are typically complex, expensive, and require extensive calibration for different formulations, making them impractical for many users.

By simplifying moisture measurement and reducing the labor and time spent on manual sampling and analysis, the DewTector enhances operational efficiency while providing accurate, real-time data critical for process control.

A cross-sectional view of the DewTector's product chamber, illustrating the air flow. The direct measurement approach using a hygrometer eliminates the need for complex calibrations for each formulation. (Source: Coperion)