Additive Filters

Additive filters for granulate dryers, side-by-side dryers, top-mounted dryers and central drying systems reduce harmful deposits. Additives in plastic granulates always lead to evaporation or outgassing. These are caused by the specific chemical components of the processed plastic granulates. Such outgassing leads to unwanted deposits on or in machine components, which are detrimental to the service life of the equipment. It is known from practical experience that air hoses or air ducts in particular can become clogged with additive deposits over years of continuous operation. In such cases, there is a risk of dryer infarction.

Compressed air dryers do not solve this problem because, unlike dry air dryers, they do not operate in a closed circuit and thus release the chemical components uncontrollably into the ambient air.

In many cases, such additive evaporation can be minimised by optimising the setting parameters on the pellet dryer. These optimisations are necessary so that the additives develop their desired chemical and physical properties in the finished product. Drywell pellet dryers make these optimisations possible, as all relevant drying parameters can be set and stored. Should unwanted additive deposits nevertheless occur, the use of the innovative additive filter is recommended.

To counteract harmful effects, Digicolor has developed a series of special additive filters. These are designed for installation in the return air stream of the pellet dryers. At this point, the filter separates outgassings from the return air and catches the unwanted components with a suitable filter element. This filter element is placed in a robust glass cylinder so that the contamination of the filter is visible. When the filter element is used up, it is easily and user-friendly replaced with a new element. The maintenance procedure required for this is carried out without tools.

That is why it is recommended to use the additive filters

• Additive outgassing and contamination are made visible,
• In this way, the filter also functions as an indicator for incorrect setting data,
• Pollution of the process air with additive vapours is significantly reduced,
• Unintentional additive deposits in the machine/dryer are greatly reduced,
• System failures due to creeping contamination of pipes and hoses are reduced,
• The service life of the equipment is extended and maintenance work on dryers is facilitated.

Installation of the filter at the dryer

Due to the standardised pipe diameters, additive filters can be installed quickly and easily with suitable pipe connectors on granulate dryers and drying systems. These additive filters can even be retrofitted to existing dryers. If diameters do not match exactly, it is possible to adapt the additive filter to the return air piping using suitable spacers.