# Rates of High-Temperature Evaporation of Promising Fire-Extinguishing Liquid Droplets
## 2 Materials  
In the experiments, the droplets of the studied liquids of the required volume were formed with the help of a multi-channel dispenser Finnpipette Novus. The step of volume variation was 0.1 \(\upmu\)L. In accordance with recommendations formulated on the basis of experimental results of References [7; 8; 9; 10; 11], the initial volume of droplets was chosen as \(V_{\text{d}}\approx\) 10 \(\upmu\)L (corresponding to the radius \(R_{\text{d}}\approx\) 0.84 mm). The choice of volume and, accordingly, the size of the drop was conditioned by the possibility to place the drop on the substrate and holders in the flow and muffle furnace (the drop did not break off from the latter). It was also possible to record the rate of reduction of its size due to heating and evaporation. Water without impurities, foaming agent emulsion, bentonite suspension, bischofite solution, and Extinguishing Agent-5 (EA-5) solution were used as the studied liquids in the experiments. All solutions, suspensions, and emulsions were prepared by stirring for 10 minutes using an ultrasonic bath Sapphire 2.8. This approach minimized the effects of stratification and the heterogeneity of concentration of components in the container from which liquids were taken by the Finnpipette Novus dispenser. Table 1 shows typical ranges of variation in relative mass concentrations of water additives in forest fire suppression and localization. According to these ranges, it can be concluded that the maximum value of such concentrations for all types of impurities is generally 10%. In this regard, in this paper, we used compositions with maximum concentrations, in particular: 10% foaming agent emulsion, 10% bentonite suspension, 10% bischofite solution, and 10% EA-5 solution. Table 1 presents regulatory documents, which determine requirements for the extinguishing agents using these water additives. The thermophysical and rheological characteristics of the latter and the prepared compositions were generally determined using the known techniques. In particular, the thermophysical properties of all additives were defined by preparing solid pellets. The system DLF-1200 TA Instruments was used to provide measurements at temperatures in the thermostat of up to 1773 \({}^{\circ}\)C. Its principle of operation is based on evaluating the propagation velocity of the heat pulse in the sample. Errors of temperature diffusivity coefficients were \(\pm 2.3\%\), for heat capacity were \(\pm 4\%\), and were \(\pm 5\%\) for thermal conductivity. For water, the coefficients of thermal conductivity, heat capacity, and temperature diffusivity were taken in accordance with the reference data. The values of thermophysical characteristics of solutions, suspensions, and emulsions were calculated under the assumption of their additivity, taking into account the fractions of components. Surface tension, density, and viscosity were determined for each prepared solution, emulsion, and suspension. The viscosity of the compositions was studied using Brookfield DV3T LV viscometer at room temperature of the liquid (within the range of 20-23 \({}^{\circ}\)C). To measure the viscosity of liquids, the standard set of viscometer included four spindles. The rotation velocity of the spindles ranged from 10-250 rpm. The measurement error of the unit in accordance with ASTM D445 was \(\pm 1\%\). The surface tension was measured using the Krus K6 tensiometer by the ring method (du Nouy method) at a temperature of 20 \({}^{\circ}\)C. The device was calibrated by measuring