The CTU UCEEB fire laboratory together with the company Prusa Research as verified the behavior of 3D printers in the newly developed box Original Prusa Enclosure. The tests took place as part of an initiative effort to solve the fire safety of 3D printing, which today is a common accessory in development, production or education.
The idea to develop and test a box for a 3D printer arose as a reaction of Prusa Research to the effort to create a stable printing environment with increased temperature for printing advanced materials. Another function of the box is preventive protection of the user, which is becoming required when placing 3D printers in schools, for example in neighboring Germany.
During testing, we confirmed that the Original Prusa Enclosure's design with a metal floor, metal ceiling, and PETG sidewalls will sustain the flame and heat effects of a 3D printer fire inside the box. The surface temperature on the walls reached a maximum of 117 °C. It can be assumed that the temperature of the gases around the protective box will be even lower. The heat flow at a distance of 100 mm from the protective cover was completely negligible even in the test without extinguishing.
The Original Prusa Enclosure with a local fire extinguisher is an even safer level. This was activated about 2.5 minutes after the sample was ignited when the ignition source was hidden under the printed sample, and even only 40 seconds after the sample was ignited in the case of the ignition source at the nozzle - the hottest element of the entire printer.
The test samples corresponded to the normal use of a 3D printer. The printer was a production and functional version of the Original Prusa i3 MK3S+. First, pilot tests were carried out with the cover prototype, on the basis of which slight structural modifications were made. We performed a total of three experiments with the final Original Prusa Enclosure: one test without extinguishing and two tests in which we installed a local gas extinguishing system in the box area and only changed the location of the ignition source.
We placed the test samples in the corner of the test chamber, a room with dimensions of 3600 × 2400 × 2400 mm, at a height corresponding to the level of the work table of 860 mm. The ignition source was a cube of mineral wool with dimensions of approximately 50 × 50 × 50 mm soaked in 50 ml of technical alcohol. This cube has been placed on a printed product. The source was only used to create a fire situation, then its own thermal development and degradation of the flammable materials located inside the box followed.