FIELD: space engineering, in particular, methods for drying of internal lines of hydraulic systems of temperature control after drain of heat-transfer medium from the system. SUBSTANCE: the method consists in multiple successive operations of vacuuming and pressurization of the lines by dry gas, before the first cycle of vacuuming the internal volume of the system after the drain of the heat-transfer medium and the temperature of the drained heat-transfer medium are to be measured, each operation of vacuuming is accomplished to a pressure below the pressure of saturated vapors of the drained heat-transfer medium at the measured temperature, each operation of system pressurization by dry gas is accomplished after the pressure of saturated vapors at the measured temperature is attained, the quantity of successive cycles of vacuuming and pressurization is selected from relation: 
where Vmeas.0 - line volume measured before the filling of the system by heat-transfer medium; Vmeas.1 - volume of the system measured after the drain of heat-transfer medium; k-coefficient of vapor production of heat-transfer medium. EFFECT: complete drying of hydraulic lines of heat-transfer medium.
