The dew point meter is a device for measuring and monitoring the dew point of the outgoing air in polymer dehumidification systems. These measurements help to ensure the effective dehumidification of plastic granules, ensuring the good quality of the finished product resulting from the plastics processing.

In this article we are going to have a closer look at what a dew point meter is and how it operates. Then we will present the features and advantages of dew point meters designed and manufactured by Vismec.

Dew point meter: what it is and how it works

When drying polymers, especially in the case of technical polymers, it is important to check the functionality and performance level of the drying system.

As we have already explained, residual moisture can be present in the granules used as a raw material for plastic processing, and it can generate serious flaws in the finished products, compromising their mechanical properties and aesthetic characteristics.

The dew point meter is a helpful tool to measure the dew point. Simply put, dew point is the temperature at which the air reaches saturation and water vapour condenses into liquid form. Consequently, in several industrial applications, knowing the dew point is useful to maintain optimal drying conditions, especially when handling moisture-sensitive materials such as plastic granules.

The operation of the dew point meter exploits precise physical principles and relies on several integrated technologies. The measuring process involves various steps. Let’s see them all.

  1. Temperature and humidity measurement. The various unit sensors detect the amount of water vapour present and the temperature of the air leaving the dehumidifier at a specific time.
  2. Dew point calculation. Using specific formulas and algorithms, the tool calculates the temperature at which the moisture in the air condenses, that is, the dew point.
  3. Data visualisation. The data are shown on a digital display to allow real-time monitoring.
  4. Process control. The most advanced dew point meters integrate into industrial process control systems, allowing automatic settings to maintain optimal dehumidification conditions.

As we said at the beginning, measuring the dew point value allows monitoring the performance of the drying system. This value can be checked in the following ways.

  • Under working conditions. In this case, the dehumidifier works regularly, as part of a real drying process of the plastic granules. The measurements taken allow controlling both the efficiency of the dehumidifier and the effectiveness of the drying process.
  • Vacuum, to check the efficiency of the dehumidifier only.

But a single measurement is not enough for a complete check. It is necessary to measure over an extended period of time to define the humidity trend over several hours, sometimes several days. 

Furthermore, the type of dehumidifier influences the duration of the measurement considerably. With VISMEC dehumidifiers, control is simple, because our machines operate smoothly and consistently: as a result, the measurement quickly shows the true dew point value, and it will not deteriorate with time. 

Vismec portable dew point meter

A Vismec portable dew point meter can be used with the different types of dehumidifiers that our company designs and manufactures. Available with various power systems, it ensures versatility and ease of reading. 

The logger plotted on the screen has an adjustable width and allows viewing the trend of the parameters over a desired, longer or shorter period of time. It is also possible to save the collected data on a USB flash drive for various uses: for example, documents filing in accordance with the company’s quality management system.

Listed below, the main technical characteristics of the dew point meter offered by our company:

  • device equipped with an integrated volumetric suction pump to ensure a correct and constant sampling flow;
  • connection to the dehumidifier via Teflon monotube;
  • great versatility, that is, the portable dew point meter is also suitable for small or pneumatic dehumidifiers;
  • large 7’ touchscreen that makes it easy to read the data, thanks to its sharpness and illumination;
  • available in rechargeable battery-powered version with integrated battery charger, or without batteries with direct power supply;
  • user-friendly graphic user interface in six languages;
  • settable dew point limit and sampling rate;
  • data collection record with possible on-screen verification;
  • USB port for downloading data and software updates;
  • total auto switch-off in case of low batteries and “battery safe” system to keep them efficient.

Effective plastic granule drying is crucial to ensure quality to the products your plastics processing company offers. In this context, Vismec portable dew point meter is a reliable, advanced and functional device that allows an accurate monitoring of the performance of installed dehumidifiers.

Want to know more? Contact our team.