The substantiation of the application of deflector sprinklers manufactured by additive technologies in experimental studies of qualitative characteristics of the low-expansion air-mechanical foam

Abstract

Purpose. Selection and evaluation of the material properties of the plastic prototype of the metal sprinkler manufacturing, the optimal parameters of the printing technology establishment, the development of a prefabricated analog of the metal sprinkler from interchangeable parts, the optimization of its elements geometry, taking into account the required reliability, functionality and the limitations of FDM printing technology, manufacturing of thermoplastic working analog of the metal sprinkler, the experimental determination of the expansion rate and stability obtained with a metal sprinkler and its thermoplastic analog by applying a solution of foaming agent of three brands from different manufacturers separately, comparison and analysis of the results.

Methods. Conducting experimental studies of the process of 3D-printing and formation of low expansion air-mechanical foam with sprinklers.

Findings. It is most expedient to use polylactide for the automatic firefighting installations sprinkler prototyping, since it has the greatest strength and rigidity values with satisfactory volumetric shrinkage, and also has the lowest anisotropy coefficient of properties compared to other materials for 3D-printing. The optimal parameters of the printing technology for the sprinkler analog elements are: layer thickness h – 0,1 mm, extruder temperature T_e – 210 °C, extruder speed v – 80 mm/s, and working table temperature T_t – 70 °C. Experimentally established values of the foam expansion rate using foaming agents of all three brands of different manufacturers showed that the difference in using a metal sprinkler and a thermoplastic sprinkler is not more than 1,7 %. The difference in the stability of the foam values is also within the measurement error and is not more than 2,1 %. This implies that the properties of the polylactide and the features of the 3D printing technology do not substantially distort the original design of the metal sprinkler and do not have a significant effect on the quality characteristics of the foam.

Application field of research. The obtained results of experimental studies can be used to improve the efficiency of firefighting with sprinklers in foam automatic firefighting installations by determining the optimal parameters of the sprinkler deflector construction.

Conclusions. The selected equipment, printing technology and material (polylactide) for the manufacturing of experimental samples, as well as the developed prefabricated design of the sprinkler prototype, which elements are made by 3D-printing, allow this technology to be used for prototyping elements of automatic fire extinguishing systems, in particular sprinkler’s deflector, with the end items having the necessary strength and rigidity.