For hot melt tanks with grid systems, the sensor is mounted above the grid and detects when the level of glue is below a specified height. Refilling is usually accomplished manually or automatically with a short filling timer.
Level detection of hot melt glue has many technical hurdles that need to be overcome. Most sensors will not work in the extreme heat inside of the melting tank and will not be reliable due to the viscous nature of glue. This is especially true when the machine is turned off and the glue is allowed to harden. This also creates other stresses with expansion and compression of the glue changing states.
The solution is Rechner’s KFS series of sensors. These durable sensors are designed to work in direct contact with the glue in extreme temperatures of up to 250°C for PTFE or PEEK housings (200°C for GFK housings) and can ignore massive amounts of glue build-up on the sensor to give you a reliable switching point the very first time you turn your machine on.
Download the complete hot melt glue level detection application note from Rechner. Find other application notes here.